:: wikimiki.org ::

Heredity

Heredity

Heredity (the adjective is hereditary) is the transfer of characteristics from parent to offspring, either through their genes or through the social institution called inheritance (for example, a title of nobility is passed from individual to individual according to relevant customs and/or laws).

Biology

In biology, heredity refers to the transference of biological characteristics from a parent organism to offspring, and is practically a synonym for genetics, as genes are now recognized as the carriers of biological information. In humans, defining which characteristics of a final person are due to heredity and which are due to environmental influences is often a site of controversy (the nature versus nurture debate), especially regarding intelligence and race.

History of heredity in biology

It was apparent to ancient humans that offspring resembled their parents. For example, Genesis 30-46 tells how Jacob and Laban split their sheep into white and speckled varieties so they could distinguish the two to ensure none was later stolen. Although it was clear that traits were hereditary, the precise mechanism of heredity was however not clear. Various hereditary mechanisms were envisaged without being properly tested or quantified. These included blending inheritance and the inheritance of acquired characters. Nevertheless, people were able to develop domestic breeds animals through artificial selection. The inheritance of acquired characters formed part of early Lamarckian ideas on evolution. Charles Darwin proposed a theory of evolution in 1859 and one of its major problems was a lack of coherent hereditary mechanism. Darwin believed in a mix of blending inheritance and the inheritance of acquired characteristics (pangenesis). Blending inheritance would lead to uniformity across populations in only a few generations and thus would remove variation from a population on which natural selection could act. This led to Darwin adopting some Lamarckian ideas in later editions of The Origin and his later biological works. Darwin's primary approach to heredity was to outline how it appeared to work (noticing that characteristics could be inherited which were not expressed explicitly in the parent at the time of reproduction, that certain characteristics could be sex-linked, etc.) rather than suggesting mechanisms. Darwin's initial model of hereditary was adopted by, and then heavily modified by, his cousin Francis Galton, who laid the framework for the biometric school of heredity. Galton rejected the aspects of Darwin's pangenesis model which relied on acquired characteristics. The inheritance of acquired characteristics was shown to have little basis in the 1880s when August Weismann cut the tails off mice to find that their offspring did develop tails. The idea of particulate inheritance of genes can be attributed to the Austrian monk Gregor Mendel who published on pea plants in 1865. However, his work was not widely known and was only rediscovered in 1901. On rediscovery of Mendel's work it was initially assumed the Mendelian inheritance only accounted for large differences, such as those seen by Mendel in his pea plants — and the additive effect of genes was not realised until Ronald Fisher's (1918) paper on The Correlation Between Relatives on the Supposition of Mendelian Inheritance. For the subsequent history of genetics, see history of genetics. In the 1930s, work by Fisher and others resulted in a combination of Mendelian and biometric schools into the modern synthesis of evolution. Lysenkoism in the Soviet Union emphasised incorrectly the inheritance of acquired characters. The inheritance of acquired characters appealed to the communist leaders, Lysenkoist movement being led by Trofim Lysenko. This led to food shortages into the 1960s and seriously affected the USSR.

Sociology

The social institution called inheritance. One's bloodline is one's familial ancestry. See also meme.

External links

- [http://plato.stanford.edu/entries/heredity/ Stanford Encyclopedia of Philosophy entry on Heredity and Heritability]

Parent

:"Parent" redirects here. For other meanings, see Parent (disambiguation). Parenting is the process of raising a child from birth until they reach adulthood. This task is usually done by the biological parents, but if the parents are unable or unwilling to provide care, the task is usually deferred to adoptive parents, foster parents, close relatives (including older siblings), godparents, or institutions (such as group homes or orphanages). An integral part of parenting is education of the child. (For further details on the education of children, see Education)

Aspects of parenting

- Physical care:
- Reliably providing shelter, education, medical care, physical safety and nourishment.
- Social development and emotional support:
- Love, entertainment and physical touch.
- Social skills and etiquette.
- Ethics and value systems.
- Moral and spiritual development.
- Norms and contributions to the child's religion and ethnic customs.
- Financial support:
- Money provided by non-custodial parents, following a divorce.
- Insurance coverage and payments for education.

Parenting Methods and Practices

Parenting may involve praise, but it also involves punishment. Some parents no longer consider spanking a necessary punishment. The term "child training" implies a specific type of parenting that focuses on holistic understanding of the child. The "Taking Children Seriously" philosophy sees both praise and punishment as manipulative and harmful to the child and seeks other way to reach agreement with them. The term "attachment parenting" seeks to create strong emotional bonds and avoid physical punishment, with discipline being accommodated by interactions with a child's emotional needs.
- Discipline:
- Time-out
- Spanking
- Taking Children Seriously (TCS) philosophy
- Parental supervision
- Parenting Fundamentals:
- Structure
- Accountability
- Consistency
- Motivation

Pregnancy and the early years

During pregnancy the unborn child is affected by many decisions his or her parents make, particularly choices linked to their lifestyle. The health and diet decisions of the mother can have either a positive or negative impact on the child.

During infancy

Specific care includes:
- Providing food and drink, and in the case of younger children, the process of feeding or helping with that.
- Providing a toilet and facilities for washing, and in the case of younger children, the washing itself or helping with that, and providing diapers or helping using the toilet (Potty Training).
- providing clothing, and in the case of small children, putting the clothes on and taking them off or helping with that;
- Infant care:
- Breastfeeding
- Baby bottle

School years

- Education:
- preschool education
- arranging for a school to provide formal education,
- finishing school

Assistance

Parents may receive assistance from a variety of individuals and organizations. Employers may offer specific benefits or programs for parents.
- Parental leave

Observers

Benjamin Spock was an authority on parenting to a generation of North American parents. A current authority is T. Berry Brazelton, the founder of the Child Development Unit at Children's Hospital, Boston, and Professor of Pediatrics Emeritus at Harvard Medical School. Also see James Dobson

Parenting assessment

There are several parent self-report measures that have been developed for use by clinicians and researchers to assess parenting, such as the Parenting Stress Index (PSI; Abidin, 1995) and Adult-Adolescent Parenting Inventory (AAPI; Bavolek, 1984). Parenting measures can also be observational, such as the Parent-Child Interaction Assessment-II (PCIA-II; Holigrocki, Kaminski, & Frieswyk, 1999). See:
- Abidin, R. (1995). Parenting Stress Index: Professional Manual. 3rd Ed. Lutz, FL: Psychological Assessment Resources, Inc.
- Bavolek, S. J. (1984). Handbook for the Adult-Adolescent Parenting Inventory. Eau Claire, Wisconsin: Family Development Associates, Inc.
- Holigrocki, R. J, Kaminski, P. L., & Frieswyk, S. H. (1999). Introduction to the Parent-Child Interaction Assessment. Bulletin of the Menninger Clinic, 63(3), 413–428.

External links

- [http://www.babyandkidsonline.com/ Parenting Information] Articles and news about parenting
- [http://www.pregnancybirthandbaby.co.uk/wiki Parenting wiki] Detailed parenting wiki
- [http://www.kirkusreviews.com/kirkusreviews/reports/parenting_archive.jsp Parenting book reviews] powered by Kirkus Reports
- [http://www.babynamebox.com Baby Names Box] – a site developed with families and parents in mind
- [http://www.bbc.co.uk/parenting/ BBC's parenting website]
- [http://www.apparenting.com/ Attachment parenting blog]
- [http://parenting-weblog.com/ Parenting-Weblog]
- [http://www.newmommysally.blogspot.com/ New Mommy blog]
- [http://www.bbc.co.uk/dna/h2g2/C21 BBC h2g2 Guide to Life, the Universe and Everything: Families]
- [http://www.ericdigests.org/1999-4/parenting.htm Parenting Style and Its Correlates]
- [http://www.ericdigests.org/2001-1/career.html Parenting and Career Development]
- [http://www.ericdigests.org/1996-1/face.htm The Changing Face of Parenting Education]
- [http://www.ericdigests.org/1998-2/fail.htm If an Adolescent Begins To Fail in School, What Can Parents and Teachers Do?]
- [http://facstaff.uindy.edu/~rholigrocki/pcia.htm Parent Child Interaction Assessment-II (PCIA-II)]
- [http://www.sharedparentingworks.org/ Shared Parenting Works]
- Category:Children ja:覚王山駅

Offspring

---- In biology, offspring are the product of reproduction, a new organism produced by one or more parents. Human offspring (descendants) are referred to as children (without reference to age, thus one can refer to a parent's "minor children" or "adult children"); male children are sons and female children are daughters. See kinship and descent. simple:offspring

Gene

:For the musical band, see Gene (band) Gene (band) (right). Introns are regions often found in eukaryote genes which are removed in the splicing process: only the exons encode the protein. This diagram labels a region of only 40 or so bases as a gene. In reality many genes are much larger.]] Genes are regions of the DNA that parents pass to offspring during reproduction as chromosomes in nuclei of gametes. These entities encode information essential for the construction and regulation of proteins (such as enzymes) and other molecules that determine the growth and functioning of the organism. The word "gene" comes from the Greek genos ("origin") and is shared by many disciplines, including classical genetics, molecular genetics, evolutionary biology and population genetics. Because each discipline models the biology of life differently, the usage of the word gene varies between disciplines. It may refer to either material or conceptual entities. Following the discovery that DNA is the genetic material, and with the growth of biotechnology and the project to sequence the human genome, the common usage of the word "gene" has increasingly reflected its meaning in molecular biology. In the molecular-biological sense, genes are the segments of DNA which cells transcribe into RNA and translate, at least in part, into proteins. The [http://song.sourceforge.net/ Sequence Ontology] project defines a gene as: "A locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions and/or other functional sequence regions". In common speech, "gene" is often used to refer to the hereditary cause of a trait, disease or condition—as in "the gene for obesity." Speaking more precisely, a biologist might refer to an allele or a mutation that has been implicated in or is associated with obesity. This is because biologists know that many factors other than genes decide whether a person is obese or not: eating habits, exercise, prenatal environment, upbringing, culture and the availability of food, for example. Moreover, it is very unlikely that variations within a single gene—or single genetic locus—fully determine one's genetic predisposition for obesity. These aspects of inheritance—the interplay between genes and environment, the influence of many genes—appear to be the norm with regard to many and perhaps most ("complex" or "multi-factoral") traits. The term phenotype refers to the characteristics that result from this interplay (see genotype-phenotype distinction).

Overview

Properties of genes

In molecular biology, the DNA of a gene encodes the chemical structure of a protein. The genetic code determines the sequence of the amino acids that make up a protein. The coding of a three nucleotide DNA sequence to a specific amino acid is essentially the same for all known life, from bacteria to humans. Through the proteins they encode, genes govern the cells in which they reside. In multicellular organisms they control the development of the individual from the fertilized egg and the day-to-day functions of the cells that make up tissues and organs. The instrumental roles of their protein products range from mechanical support of the cell structure to the transportation and manufacture of other molecules and to the regulation of other proteins' activities. The genes that exist today are those that have reproduced successfully in the past. Often, many individual organisms share a gene; thus, the death of an individual need not mean the extinction of the gene. Indeed, if the sacrifice of one individual enhances the survivability of other individuals with the same gene, the death of an individual may enhance the overall survival of the gene. This is the basis of the selfish gene view, popularized by Richard Dawkins. He points out in his book, The Selfish Gene, that to be successful genes need have no other "purpose" than to propagate themselves, even at the expense of their host organism's welfare. A human that behaved in such a way would be described as "selfish," although ironically a selfish gene may promote altruistic behaviours. According to Dawkins, the possibly disappointing answer to the question "what is the meaning of life?" may be "the survival and perpetuation of ribonucleic acids and their associated proteins".

Types of genes

Due to rare, spontaneous errors (e.g. in DNA replication) mutations in the sequence of a gene may arise. Once propagated to the next generation, this mutation may lead to variations within a species' population. Variants of a single gene are known as alleles, and differences in alleles may give rise to differences in traits, for example eye colour. A gene's most common allele is called the wild type allele, and rare alleles are called mutants. Normally, RNA is an intermediate product in the translation of a molecular gene into a protein. However, for some gene sequences, RNA molecules are actually the functional products. For example, RNAs known as ribozymes are capable of enzymatic function, or small interfering RNAs have a regulatory role. The DNA sequences from which such RNAs are transcribed are known as non-coding RNA, or RNA genes. All living organisms carry their genes and transmit them to offspring as DNA, but some viruses carry only RNA. Because they use RNA, their cellular hosts may synthesize their proteins as soon as they are infected and without the delay in waiting for transcription. On the other hand, RNA retroviruses, such as AIDS, require the reverse transcription of their genome from RNA into DNA before their proteins can be synthesized.

Human gene nomenclature

For each known human gene the HUGO Gene Nomenclature Committee (HGNC) approve a gene name and symbol (short-form abbreviation). All approved symbols are stored in the [http://www.gene.ucl.ac.uk/cgi-bin/nomenclature/searchgenes.pl HGNC Database]. Each symbol is unique and each gene is only given one approved gene symbol. It is necessary to provide a unique symbol for each gene so that people can talk about them. This also facilitates electronic data retrieval from publications. In preference each symbol maintains parallel construction in different members of a gene family and can be used in other species, especially the mouse.

Typical numbers of genes in an organism

The following table gives typical numbers of genes and genome size for some organisms. Estimates of the number of genes in an organism are somewhat controversial because they depend on the discovery of genes, and no techniques currently exist to prove that a DNA sequence contains no gene. (In early genetics, genes could be identified only if there were mutations, or alleles.) Nonetheless, estimates are made based on current knowledge.

Chemistry and function of genes

Chemical structure of a gene

Four kinds of sequentially linked nucleotides compose a DNA molecule or strand (more at DNA). These four nucleotides constitute the genetic alphabet. A sequence of three consecutive nucleotides, called a codon, is the protein-coding vocabulary. The sequence of codons in a gene specifies the amino-acid sequence of the protein it encodes. In most eukaryotic species, very little of the DNA in the genome encodes proteins, and the genes may be separated by vast sequences of so-called junk DNA. Moreover, the genes are often fragmented internally by non-coding sequences called introns, which can be many times longer than the genes themselves. Introns are removed on the heels of transcription by splicing. In the primary molecular sense, they represent parts of a gene, however. All the genes and intervening DNA together make up the genome of an organism, which in many species is divided among several chromosomes and typically present in two or more copies. The location (or locus) of a gene and the chromosome on which it is situated is in a sense arbitrary. Genes that appear together on the chromosomes of one species, such as humans, may appear on separate chromosomes in another species, such as mice. Two genes positioned near one another on a chromosome may encode proteins that figure in the same cellular process or in completely unrelated processes. As an example of the former, many of the genes involved in spermatogenesis reside together on the Y chromosome. Many species carry more than one copy of their genome within each of their somatic cells. These organisms are called diploid if they have two copies or polyploid if they have more than two copies. In such organisms, the copies are practically never identical. With respect to each gene, the copies that an individual possesses are liable to be distinct alleles, which may act synergistically or antagonistically to generate a trait or phenotype. The ways that gene copies interact are explained by chemical dominance relationships (more at genetics, allele).

Expression of molecular genes

For various reasons, the relationship between DNA strand and a phenotype trait is not direct. The same DNA strand in 2 different individuals may result in different traits because of the effect of other DNA strands or the environment.
- The DNA strand is expressed into a trait only if it is transcribed to RNA. Because the transcription starts from a specific base-pair sequence (a promoter) and stops at another (a terminator), our DNA strand needs to be correctly placed between the two. If not, it is considered as junk DNA, and is not expressed.
- Cells regulate the activity of genes in part by increasing or decreasing their rate of transcription. Over the short term, this regulation occurs through the binding or unbinding of proteins, known as transcription factors, to specific non-coding DNA sequences called regulatory elements. Therefore, to be expressed, our DNA strand needs to be properly regulated by other DNA strands.
- The DNA strand may also be silenced through DNA methylation or by chemical changes to the protein components of chromosomes (see histone). This is a permanent form of regulation of the transcription.
- The RNA is often edited before its translation into a protein. Eukaryotic cells splice the transcripts of a gene, by keeping the exons and removing the introns. Therefore, the DNA strand needs to be in an exon to be expressed. Because of the complexity of the splicing process, one transcribed RNA may be spliced in alternate ways to produce not one but a variety of proteins (alternative splicing) from one pre-mRNA. Prokaryotes produce a similar effect by shifting reading frames during translation.
- The translation of RNA into a protein also starts with a specific start and stop sequence.
- Once produced, the protein interacts with the many other proteins in the cell, according to the cell metabolism. This interaction finally produces the trait. This complex process helps explain the different meanings of "gene":
- a nucleotide sequence in a DNA strand;
- or the transcribed RNA, prior to splicing;
- or the transcribed RNA after splicing, i.e. without the introns The latter meaning of gene is the result of more "material entity" than the first one.

Mutations and evolution

Just as there are many factors influencing the expression of a particular DNA strand, there are many ways to have genetic mutations. For example, natural variations within regulatory sequences appear to underlie many of the heritable characteristics seen in organisms. The influence of such variations on the trajectory of evolution through natural selection may be as large as or larger than variation in sequences that encode proteins. Thus, though regulatory elements are often distinguished from genes in molecular biology, in effect they satisfy the shared and historical sense of the word. Indeed, a breeder or geneticist, in following the inheritance pattern of a trait, has no immediate way to know whether this pattern arises from coding sequences or regulatory sequences. Typically, he or she will simply attribute it to variations within a gene. Errors during DNA replication may lead to the duplication of a gene, which may diverge over time. Though the two sequences may remain the same, or be only slightly altered, they are typically regarded as separate genes (i.e. not as alleles of the same gene). The same is true when duplicate sequences appear in different species. Yet, though the alleles of a gene differ in sequence, nevertheless they are regarded as a single gene (occupying a single locus).

History

The existence of genes was first suggested by Gregor Mendel, who, in the 1860s, studied inheritance in pea plants and hypothesized a factor that conveys traits from parent to offspring. Although he did not use the term gene, he explained his results in terms of inherited characteristics. Mendel was also the first to hypothesize independent assortment, the distinction between dominant and recessive traits, the distinction between a heterozygote and homozygote, and the difference between what would later be described as genotype and phenotype. Mendel's concept was finally named when Wilhelm Johannsen coined the word gene in 1909. In the early 1900s, Mendel's work received renewed attention from scientists. In 1910, Thomas Hunt Morgan showed that genes reside on specific chromosomes. He later showed that genes occupy specific locations on the chromosome. With this knowledge, Morgan and his students began the first chromosomal map of the fruit fly Drosophila. In 1928, Frederick Griffith showed that genes could be transferred. In what is now known as Griffith's experiment, injections into a mouse of a deadly strain of bacteria that had been heat-killed transferred genetic information to a safe strain of the same bacteria, killing the mouse. In 1941, George Wells Beadle and Edward Lawrie Tatum showed that mutations in genes caused errors in certain steps in metabolic pathways. This showed that specific genes code for specific proteins, leading to the "one gene, one enzyme" hypothesis. Oswald Avery, Collin Macleod, and Maclyn McCarty showed in 1944 that DNA holds the gene's information. In 1953, James D. Watson and Francis Crick demonstrated the molecular structure of DNA. Together, these discoveries established the central dogma of molecular biology, which states that proteins are translated from RNA which is transcribed from DNA. This dogma has since been shown to have exceptions, such as reverse transcription in retroviruses.

Evolutionary concept of gene

George C. Williams first explicitly advocated the gene-centered view of evolution in his book Adaptation and Natural Selection. Also, he proposed an evolutionary concept of gene to be used when we are talking about natural selection favoring some gene. The definition is: ""that which segregates and recombines with appreciable frequency." Acording to this definition, even an asexual genome could be considered a gene, insofar it have an appreciable permanency through many generations. The difference is: the molecular gene transcribes as a unit, and the evolutionary gene inherits as a unit. Richard Dawkins' The Selfish Gene and The Extended Phenotype defended that the gene is the only replicator in livings systems. This means that only genes transmit their structure largely intact and are potentially immortal in the form of copies. So, genes should be the unit of selection.

References

[http://print.google.com/print?id=WkHO9HI7koEC Google print]

External links

- [http://www.gene.ucl.ac.uk/nomenclature HUGO Gene Nomenclature Committee, HGNC]
- [http://www.gene.ucl.ac.uk/cgi-bin/nomenclature/searchgenes.pl the HGNC Database]
- [http://www.gene.ucl.ac.uk/hugo/ Human Genome Organisation, HUGO]
- [http://www.newscientist.com/news/news.jsp?id=ns99996561 Recount slashes number of human genes] (from New Scientist magazine)
- [http://www.genome.gov/12513430 National Human Genome Research Institute — News Release]
- [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v431/n7011/full/nature03001_fs.html Nature - 21 October 2004 — Finishing the euchromatic sequence of the human genome]
- [http://www.ncbi.nlm.nih.gov/mapview/stats/BuildStats.cgi?taxid=10116&build=3&ver=1#contigs Rat Genome]
- [http://plato.stanford.edu/entries/gene/ Stanford Encyclopedia of Philosophy entry]
- [http://www.ihop-net.org/UniPub/iHOP/ iHOP - Information Hyperlinked over Proteins]
- [http://www.pir.uniprot.org/ UniProt] Category:Cloning Category:Genetics Category:Molecular biology ko:유전자 ja:遺伝子 simple:Gene th:หน่วยพันธุกรรม

Inheritance

: Inheritance is the practice of passing on property, titles, debts, and obligations upon the death of an individual. It has long played an extremely important role in human societies. Both anthropology and sociology have made detailed studies in this area. Many cultures feature patrilineal succession, also known as gavelkind, where only male children can inherit. Some cultures also employ matrilineal succession only passing property along the female line. Even more radical than the patrilineal succession is the practice of primogeniture whereby all property goes to the eldest child, or often the eldest son (the first-born). Conversely there are also systems where everything is left to the youngest child. Some ancient societies and most modern states employ partible inheritance, whereby every child inherits (usually equally). There was also mixed systems:
- in Swedish culture beginning from 13th century and up until 19th century, a son inherited twice as much as his sister. This rule was introduced by the Regent Birger Jarl, and it was regarded as an improvement in its era, since daughters were previously usually left without.
- among ancient Israelites, the eldest son received twice as much as the other sons. Many modern states have inheritance taxes, whereby a portion of any estate goes to the government, though the government technically is not an heir. Employing differing forms of succession can effect many areas of society. Gender roles are profoundly affected by inheritance laws and traditions. Primogeniture has the effect of keeping large estates united and thus perpetuating an elite. With partible inheritance large estates are slowly divided among many descendants and great wealth is thus diluted, leaving higher opportunities to individuals to make a success. (If great wealth is not diluted, the positions in society tend to be much more fixed and opportunities to make an individual success are lower.) Inheritance can be organized in a way that its use is restricted by the desires of someone (usually of the decedent). An inheritance may have been organized as a fideicommission, which usually cannot be sold or diminished, only its profits are disposable. A fideicommission's succession can also be ordered in a way that determines it long (or eternally) also with regard to persons born long after the original decedent. Cf also trust. Royal succession has typically been more or less a fideicommission, the realm not (easily) to be sold and the rules of succession not to be (easily) altered by a holder (a monarch). In more archaic days, particularly the possession of inherited land has been much more like a family trust than a property of an individual. Yet quite recently in many European countries, sale of the whole of or a significant portion of a farm required consent from certain heirs, and/or heirs had the intervening right to obtain the land in question with same sales conditions as in the sales agreement in question. In common law jurisdictions an heir is a person who is entitled to receive a share of the decedent's property via the rules of inheritance in the jurisdiction where the decedent died or owned property at the time of his death. Strictly speaking, one only becomes an heir upon the death of the related person: it was improper to speak of the "heir" of a living person since the exact identity of the persons entitled to inherit would not be determined until the time of death. However, it is not totally wrong to speak about "heir" during the lifetime of the decedent at least in cases where the heir has such a position that only her/his own demise before, may prevent becoming a heir at the death (for example, if the birth of another person cannot take away the position as a heir) - this is a heir apparent.

Custom

Custom has a number of meanings:
- A custom is a common practice among a group of people, especially depending on country, culture, time, and religion.
- See norm (sociology).
- For legal usage, see custom (law).
- Usually plural, customs duty is a tarriff on imported or exported goods.
- Custom may also be used to mean customized.
- In computing, a custom program is one that has been written or modified according to the requirements of a particular customer.
- A custom is a customized motorbike or car; see custom motorcycle, custom car, and Kustom Kulture
- The Custom is a model of guitar produced by Fender. simple:Custom

Law

:This article is about law in society. For other possible meanings, see law (disambiguation). Law (a loanword from Old Norse lag), in politics and jurisprudence, is a set of rules or norms of conduct which mandate, proscribe or permit specified relationships among people and organizations, provide methods for ensuring the impartial treatment of such people, and provide punishments of/for those who do not follow the established rules of conduct. Law is typically administered through a system of courts, in which judges hear disputes between parties and apply a set of rules in order to provide an outcome that is just and fair. The manner in which law is administered is known as a legal system, which typically has developed through tradition in each country. Legal practitioners, most often, must be professionally trained in the law before they are permitted to advocate for a party in a court of law, draft legal documents, or give legal advice.

Legal traditions

There are generally four broad legal traditions that are practiced in the world today.

Civil law

The Civilian system of law is a codified law that sets out a comprehensive system of rules that are applied and interpreted by judges. It is by and large the most commonly practiced system of law in the world, with almost 60 % of the world's population living in a country ruled on the civilian system. The most important difference to common law is that normally, only legislative enactments are considered to be legally binding, but not precedent cases. However, as a practical matter, courts normally follow their previous decisions. Furthermore, in some civil law systems (e.g. in Germany), the writings of legal scholars have considerable influence on the courts. In most jurisdictions the core areas of private law are codified in the form of a civil code, but in some, like Scotland it remains uncodified. The civil law system has its origins in Roman law, which was adopted by scholars and courts from the late middle ages onwards. Most modern systems go back to the 19th century codification movement. The civil codes of many, particularly Latin countries and former French and Spanish colonies closely trail the Code de Napoléon in some fashion. However, this is not true for most Central and Eastern European, Scandinavian and East Asian countries. Notably, the German BGB was developed from Roman law with reference to German legal tradition. The importance of the Code Napoléon should also not be overemphasized as it covers only the core areas of private law, while other codes and statutes govern fields such as corporate law, administrative law, tax law and constitutional law.

Common law

The Common law is an Anglo-Saxon legal tradition, based on unwritten laws developed through judicial decisions that create binding precedent. The common law system is currently in practice in Australia, Canada (excluding Quebec), United Kingdom, and the United States (excluding Louisiana). In addition to these countries several others have adapted the common law system into a mixed system. For example, India and Nigera operate largely on a common law system but incorporate a good deal of customary law and religious law.

Customary law

Customary law are systems of law that has evolved largely on their own within a given country and have been adapted to meet the needs of the particular culture. Note that customary law may also be relevant within jurisdictions following another legal tradition in fields or subfields of law where no legislative enactment exists. For example, in Austria, scholars of private law often claim that customary law continues to exist, whereas public law scholars dispute this claim. (In any case, it is hard to find any practically relevant examples.)

Religious law

Many countries base their system of law on religious tenants. The most dominant system of this form of law is Muslim law (or "Sharia") which is a codified law that is found within the Koran. These laws deal primarily with the personal rights and dispute resolution between individuals. It is used in some Middle Eastern nations; such as in the Iran and Saudi Arabia. On a smaller level there are still regions of the world that practice canon law, which is followed by Catholics and Anglicans, and a similar legal system is used by the Eastern Orthodox Church. The same can be said for Jewish law (halakha or halacha), which is followed by Orthodox and Conservative Jews, in substantially different forms.

Bodies of law

In the broadest sense, bodies of law can be subdivided on the basis of who the parties to an action are. It is frequent that practiced fields of law overlap into several of these bodies of law.

Private law

The area of private law in a legal system concerns law that oversees disputes between private individuals. This area is, to a large extent, the most comprehensive area of law, dealing with all non-criminal harm one person does to another.

Public law

The area of public law, in a general sense, is the law in a given legal system that concerns disputes between the government and private individuals residing within the country. The state can bring actions against people for criminal acts, as well as breach of regulatory laws. Equally, individuals can bring actions against the government for harm it has done. This includes grounds on the basis of a breach of regulations, legislate on matters beyond their competence, or violation of an individuals rights. These last two points are often protected under a countries’ constitution.

Procedural law

Procedural law concerns the areas of law that regulate how all actions are dealt with. This includes who can have access to the court system, how complaints are submitted, and what are the rights of the parties involved. Procedural law is often known as "adjective" law as it is the law that concern how other laws are to be applied. Typically, this is broadly covered by a government’s civil and criminal procedure rules. But equally this includes the law of evidence which determines what means are used to prove facts, as well as, the law regarding remedies.

International law

International law governs the relations between states, or between citizens of different states, or international organizations. Its two primary sources are customary law and treaties.

Philosophy of law

Philosophy of law is a branch of philosophy and jurisprudence which studies basic questions about law and legal systems, such as "what is the law?", "what are the criteria for legal validity?", "what is the relationship between law and morality?", and many other similar questions. In the western tradition there are several schools of thought on the philosophical basis of law. First, there is natural law, which attempts to describe law as an inherent quality in humans that is derived from natures. Second, there is the positivism which believes that law is a purely human-made construct that society uses to maintain social order. Third, there is legal realism which believes that law is an arbitrary set of rules that are largely established through the tastes and preferences of judges.

Anthropology of law

:See main discussion at Honour Law has an anthropological dimension. It has been recognized from Montesquieu to the present that law is shaped by the kind of society in which it is practised. One continuum into which various societies can be placed contrasts the "culture of law" with the "culture of honour". In order to have a culture of law, people must dwell in a society where a government exists whose authority is hard to evade and generally recognised as legitimate. People take their grievances before the government and its agents, who arbitrate disputes and enforce penalties. This behaviour is contrasted with the culture of honour, where respect for persons and groups stems from fear of the revenge they may exact if their person, property, or prerogatives are not respected. Cultures of law must be maintained. They can be eroded by declining respect for the law, achieved either by weak government unable to wield its authority, or by burdensome restrictions that attempt to forbid behaviour prevalent in the culture or in some subculture of the society. When a culture of law declines, there is a possibility that an culture of honor will arise in its place.
History

Practice of law
Practice of law is typically overseen by either a government organization or independent regulating body such as a bar association or barrister society. To practice law – i.e. appear in front of a judge on behalf of someone, draft legal documents, etc. – the practitioner must be certified by the regulating body. This usually entails a two or three year program at a university’s faculty of law or a law school, followed by an entrance examination (eg. bar admissions). Once accredited, a legal practitioners will often work in law firm, as well as in government, a private corporation, or even work as sole practitioner. A significant component to the practice of law in the common law tradition involves legal research in order to determine the current state of the law. This usually entails exploring case reporters, legal periodicals, and legislation.
See also

- Law topics overview
- List of areas of law
- List of legal topics
- List of legal terms
- List of jurists
- List of legal abbreviations
- List of case law lists
- List of law firms
Further reading

- Cheyenne Way: Conflict & Case Law in Primitive Jurisprudence, Karl N. Llewellyn and E. Adamson Hoebel, University of Oklahoma Press, 1983, trade paperback, 374 pages, ISBN 0806118555
- The Bilingual LSP Dictionary. Principles and Practice for Legal language, Sandro Nielsen, Gunter Narr Verlag 1994.
- [http://browse.addall.com/Browse/Author/2088479-1 Other books by Karl N. Llewellyn]
- David, René, and John E. C. Brierley. Major Legal Systems in the World Today: An Introduction to the Comparative Study of Law. 3d ed. London: Stevens, 1985 (ISBN 0420473408).
External links

- [http://www.legalmatch.com LegalMatch] Legal Resource
- [http://ausicl.com The Australian Institute of Comparative Legal Systems]
- [http://www.lpig.org Law and Policy Institutions]
- [http://www.llbee.com/news.php?p=news Laws External Education- Legal News By Subject]
- [http://www.4lawschool.com 4LawSchool- Legal Reference]
- [http://ww3.definitions-legal.com:8567/ Law, Legal Definitions & Reference]
- [http://www.ericdigests.org/1996-3/law.htm Essentials of Law-Related Education. ERIC Digest.]
- [http://www.law.cornell.edu LII - Topical overviews, US Supreme Court decisions, US Code (Acts of Congress)]
- [http://www.worldlii.org WorldLII - The World Legal Information Institute]
- [http://www.lawmoose.com LawMoose Legal Reference Library]
- [http://legallinks.jenkinslaw.org Legal Research Links]
- [http://www.findlaw.com FindLaw]
- [http://ausicl.com The Australian Institute of Comparative Legal Systems]
- [http://www.nolo.com/glossary.cfm Everybody's Legal Glossary] - From Nolo
- [http://www.alllaw.com/ AllLaw]
- [http://legal.wikicities.com/ WikiCities Legal Site]
- Stanford Encyclopedia of Philosophy:
- [http://plato.stanford.edu/entries/law-ideology/ Law and Ideology]
- [http://plato.stanford.edu/entries/law-language/ Law and Language]
- [http://en.jurispedia.org/ The shared law] in Jurispedia
- [http://www.avocatura.com Romanian Law]
- [http://www.thedailylaw.com Daily Law news]
- [http://members.fortunecity.com/victorcauchi/lex/lexindex.htm Laws of Malta] Chapter summaries and a general Glossary of definitions.
- [http://LawyerIntl.com LawyerIntl.com] Legal Resource and Law Dictionary
- [http://LawGuru.com LawGuru.com] Legal Portal
- [http://forumprawne.org Prawo i porady prawne] - web discussion board about Polish law Category:Core issues in ethics ja:法 (法学) simple:Law th:กฎหมาย

Biology

Biology is the study, or science, of life. It is concerned with the characteristics and behaviors of organisms, how species and individuals come into existence, and the interactions they have with each other and with the environment. Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. However, together they address the phenomenon of life over a wide range of scales. At the atomic and molecular scale, life is studied in the disciplines of molecular biology, biochemistry, and molecular genetics. At the level of the cell, it is studied in cell biology, and at multicellular scales, it is examined in physiology, anatomy, and histology. Developmental biology studies life at the level of an individual organism's development or ontogeny. Moving up the scale towards more than one organism, genetics considers how heredity works between parent and offspring. Ethology considers group behavior of more than one individual. Population genetics looks at the level of an entire population, and systematics considers the multi-species scale of lineages. Interdependent populations and their habitats are examined in ecology and evolutionary biology. A speculative new field is astrobiology (or xenobiology), which examines the possibility of life beyond the Earth.

Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle

Principles of biology

Unlike physics, biology does not usually describe systems in terms of objects which obey immutable physical laws described by mathematics. Nevertheless, the biological sciences are characterized and unified by several major underlying principles and concepts: universality, evolution, diversity, continuity, homeostasis, and interactions.

Universality: Biochemistry, cells, and the genetic code

mathematics]] Main articles: Life The most salient example of biological universality is that all living things share a common carbon-based biochemistry and in particular pass on their characteristics via genetic material, which is based on nucleic acids such as DNA and which uses a common genetic code with only minor variations. Another universal principle is that all organisms (that is, all forms of life on Earth except for viruses) are made of cells. Similarly, all organisms share common developmental processes. For example, in most metazoan organisms, the basic stages of early embryonic development share similar morphological characteristics and include similar genes.

Evolution: The central principle of biology

Main article: Evolution The central organizing concept in biology is that all life has a common origin and has changed and developed through the process of evolution (see Common descent). This has led to the striking similarity of units and processes discussed in the previous section. Charles Darwin established evolution as a viable theory by articulating its driving force, natural selection (Alfred Russell Wallace is recognized as the co-discoverer of this concept). Genetic drift was embraced as an additional mechanism of evolutionary development in the modern synthesis of the theory. The evolutionary history of a species— which describes the characteristics of the various species from which it descended— together with its genealogical relationship to every other species is called its phylogeny. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of DNA sequences conducted within molecular biology or genomics, and comparisons of fossils or other records of ancient organisms in paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics (The major events in the evolution of life, as biologists currently understand them, are summarized on this evolutionary timeline).

Diversity: The variety of living organisms

evolutionary timeline, based on rRNA gene data, showing the separation of the three domains bacteria, archaea, and eukaryotes as described initially by Carl Woese. Trees constructed with other genes are generally similar, although they may place some early-branching groups very differently, presumably owing to rapid rRNA evolution. The exact relationships of the three domains are still being debated.]] Despite its underlying unity, life exhibits an astonishingly wide diversity in morphology, behavior, and life histories. In order to grapple with this diversity, biologists attempt to classify all living things. Scientific classification seeks to reflect the evolutionary trees (phylogenetic trees) of the organism being classified. Classification is the province of the disciplines of systematics and taxonomy. Taxonomy places organisms in groups called taxa, while systematics seeks to define their relationships with each other. This clasification technique has evolved to reflect advances in cladistics and genetics, shifting the focus from physical similarities and shared characteristics to phylogenetics. Traditionally, living things have been divided into five kingdoms: :Monera -- Protista -- Fungi -- Plantae -- Animalia However, many scientists now consider this five-kingdom system to be outdated. Modern alternative classification systems generally begin with the three-domain system: :Archaea (originally Archaebacteria) -- Bacteria (originally Eubacteria) -- Eukaryota These domains reflect whether the cells have nuclei or not, as well as differences in the cell exteriors. There is also a series of intracellular parasites that are progressively "less alive" in terms of metabolic activity: :Viruses -- Viroids -- Prions

Continuity: The common descent of life

Main article: Common descent Up into the 19th century, it was commonly believed that life forms could appear spontaneously under certain conditions (see abiogenesis). This misconception was challenged by William Harvey's diction that "all life [is] from [an] egg" (from the Latin "Omne vivum ex ovo"), a foundational concept of modern biology. It simply means that there is an unbroken continuity of life from its initial origin to the present time. A group of organisms is said to share a common descent if they share a common ancestor. All organisms on the Earth have been and are descended from a common ancestor or an ancestral gene pool. This last universal common ancestor of all organisms is believed to have appeared about 3.5 billion years ago. Biologists generally regard the universality of the genetic code as definitive evidence in favor of the theory of universal common descent (UCD) for all bacteria, archaea, and eukaryotes (see: origin of life).

Homeostasis: Adapting to change

Main article: Homeostasis Homeostasis is the ability of an open system to regulate its internal environment to maintain a stable condition by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. All living organisms, whether unicellular or multicellular, exhibit homeostasis. Homeostasis manifests itself at the cellular level through the maintenance of a stable internal acidity (pH); at the organismic level, warm-blooded animals maintain a constant internal body temperature; and at the level of the ecosystem, as when atmospheric carbon dioxide levels rise and plants are theoretically able to grow healthier and remove more of the gas from the atmosphere. Tissues and organs can also maintain homeostasis.

Interactions: Groups and environments

organ of the genus Amphiprion that dwell among the tentacles of tropical sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protects the anemone fish from its predators]] Every living thing interacts with other organisms and its environment. One reason that biological systems can be difficult to study is that so many different interactions with other organisms and the environment are possible, even on the smallest of scales. A microscopic bacterium responding to a local sugar gradient is responding to its environment as much as a lion is responding to its environment when it searches for food in the African savannah. For any given species, behaviors can be co-operative, aggressive, parasitic or symbiotic. Matters become more complex when two or more different species interact in an ecosystem. Studies of this type are the province of ecology.

Scope of biology

Main article: List of biology disciplines Biology has become such a vast research enterprise that it is not generally regarded as a single discipline, but as a number of clustered sub-disciplines. This article considers four broad groupings. The first group consists of those disciplines that study the basic structures of living systems: cells, genes etc.; the second group considers the operation of these structures at the level of tissues, organs, and bodies; the third group considers organisms and their histories; the final constellation of disciplines focuses on their interactions. It is important to note, however, that these boundaries, groupings, and descriptions are a simplified characterization of biological research. In reality, the boundaries between disciplines are fluid, and most disciplines frequently borrow techniques from each other. For example, evolutionary biology leans heavily on techniques from molecular biology to determine DNA sequences, which assist in understanding the genetic variation of a population; and physiology borrows extensively from cell biology in describing the function of organ systems.

Structure of life

DNA sequences and structures]] Main articles: Molecular biology, Cell biology, Genetics, Developmental biology Molecular biology is the study of biology at a molecular level. This field overlaps with other areas of biology, particularly with genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interrelationship of DNA, RNA, and protein synthesis and learning how these interactions are regulated. Cell biology studies the physiological properties of cells, as well as their behaviors, interactions, and environment. This is done both on a microscopic and molecular level. Cell biology researches both single-celled organisms like bacteria and specialized cells in multicellular organisms like humans. Understanding cell composition and how they function is fundamental to all of the biological sciences. Appreciating the similarities and differences between cell types is particularly important in the fields of cell and molecular biology. These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Genetics is the science of genes, heredity, and the variation of organisms. In modern research, genetics provides important tools in the investigation of the function of a particular gene, or the analysis of genetic interactions. Within organisms, genetic information generally is carried in chromosomes, where it is represented in the chemical structure of particular DNA molecules. Genes encode the information necessary for synthesizing proteins, which in turn play a large role in influencing (though, in many instances, not completely determining) the final phenotype of the organism. Developmental biology studies the process by which organisms grow and develop. Originating in embryology, modern developmental biology studies the genetic control of cell growth, differentiation, and "morphogenesis," which is the process that gives rise to tissues, organs, and anatomy. Model organisms for developmental biology include the round worm Caenorhabditis elegans, the fruit fly Drosophila melanogaster, the zebrafish Brachydanio rerio, the mouse Mus musculus, and the weed Arabidopsis thaliana.

Physiology of organisms

Main articles: Physiology, Anatomy Physiology studies the mechanical, physical, and biochemical processes of living organisms by attempting to understand how all of the structures function as a whole. The theme of "structure to function" is central to biology. Physiological studies have traditionally been divided into plant physiology and animal physiology, but the principles of physiology are universal, no matter what particular organism is being studied. For example, what is learned about the physiology of yeast cells can also apply to human cells. The field of animal physiology extends the tools and methods of human physiology to non-human species. Plant physiology also borrows techniques from both fields. Anatomy is an important branch of physiology and considers how organ systems in animals, such as the nervous, immune, endocrine, respiratory, and circulatory systems, function and interact. The study of these systems is shared with medically oriented disciplines such as neurology and immunology.

Diversity and evolution of organisms

immunology of a population of organisms is sometimes depicted as if travelling on a fitness landscape. The arrows indicate the preferred flow of a population on the landscape, and the points A, B, and C are local optima. The red ball indicates a population that moves from a very low fitness value to the top of a peak]] Main articles: Evolutionary biology, Botany, Zoology Evolutionary biology is concerned with the origin and descent of species, as well as their change over time, and includes scientists from many taxonomically-oriented disciplines. For example, it generally involves scientists who have special training in particular organisms such as mammalogy, ornithology, or herpetology, but use those organisms as systems to answer general questions about evolution. Evolutionary biology also makes use of paleontologists, who use the fossil record to answer questions about the mode and tempo of evolution, as well as theoreticians in areas such as population genetics and evolutionary theory. In the 1990s, developmental biology re-entered evolutionary biology from its initial exclusion from the modern synthesis through the study of evolutionary developmental biology. Related fields which are often considered part of evolutionary biology are phylogenetics, systematics, and taxonomy. The two major traditional taxonomically-oriented disciplines are botany and zoology. Botany is the scientific study of plants. Botany covers a wide range of scientific disciplines that study the growth, reproduction, metabolism, development, diseases, and evolution of plant life. Zoology involves the study of animals, including the study of their physiology within the fields of anatomy and embryology. The common genetic and developmental mechanisms of animals and plants is studied in molecular biology, molecular genetics, and developmental biology. The ecology of animals is covered under behavioral ecology and other fields.

Classification of life

The dominant classification system is called Linnaean taxonomy, which includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Botanical Nomenclature (ICBN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in these three areas, but it has yet to be formally adopted. The International Code of Virus Classification and Nomenclature (ICVCN) remains outside the BioCode.

Interactions of organisms

International Code of Virus Classification and Nomenclature]] Main articles: Ecology, Ethology, Behavior, Biogeography Ecology studies the distribution and abundance of living organisms, and the interactions between organisms and their environment. The environment of an organism includes both its habitat, which can be described as the sum of local abiotic factors such as climate and geology, as well as the other the organisms that share its habitat. Ecological systems are studied at several different levels, from individuals and populations to ecosystems and the biosphere. As can be surmised, ecology is a science that draws on several disciplines. Ethology studies animal behavior (particularly of social animals such as primates and canids), and is sometimes considered a branch of zoology. Ethologists have been particularly concerned with the evolution of behavior and the understanding of behavior in terms of the theory of natural selection. In one sense, the first modern ethologist was Charles Darwin, whose book The expression of the emotions in animals and men influenced many ethologists. Biogeography studies the spatial distribution of organisms on the Earth, focusing on topics like plate tectonics, climate change, dispersal and migration, and cladistics.

History of the word "biology"

Formed by combining the Greek βίος (bios), meaning 'life', and λόγος (logos), meaning 'study of', the word "biology" in its modern sense seems to have been introduced independently by Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur, 1802) and by Jean-Baptiste Lamarck (Hydrogéologie, 1802). The word itself is sometimes said to have been coined in 1800 by Karl Friedrich Burdach, but it appears in the title of Volume 3 of Michael Christoph Hanov's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published in 1766.

History

Main articles: History of biology, History of medicine, History of genetics Major discoveries in biology include:
- Cell theory
- Germ theory of disease
- Genetics
- Evolution
- DNA

External links

- [http://www.rom.on.ca/biodiversity/biocode/biocode1997.html BioCode]: A proposal for organism naming.
- [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books NCBI Open-Access Books]
- PhyloCode, [http://www.ohiou.edu/phylocode/index.html]
- [http://tolweb.org/tree/phylogeny.html The Tree of Life]: A multi-authored, distributed Internet project containing information about phylogeny and biodiversity.
- [http://www.bioone.org/perlserv/?request=index-html BioOne] Bioscience research journals.
- [http://www.bionews.in/biologynews.htm Biology News] Biology News, Articles and Research discoversies.

Synonym

Synonyms (in ancient Greek syn 'συν' = plus and onoma 'όνομα' = name) are different words with similar or identical meanings and are interchangable. Antonyms are words with opposite or nearly opposite meanings. (Synonym and antonym are antonyms.) An example of synonyms are the words cat and feline. Each describes any member of the family Felidae. Similarly, if we talk about a long time or an extended time, long and extended become synonyms. In the figurative sense, two words are often said to be synonymous if they have the same connotation: :"a widespread impression that … Hollywood was synonymous with immorality" (Doris Kearns Goodwin) Synonyms can be nouns, adverbs or adjectives, as long as both members of the pair are the same part of speech. More examples of English synonyms:
- baby and infant (noun)
- student and pupil (noun)
- pretty and attractive (adjective)
- sick and ill (adjective)
- interesting and fascinating (adjective)
- quickly and speedily (adverb) Note that the synonyms are defined with respect to certain senses of words; for instance, pupil as the "aperture in the iris of the eye" is not synonymous with student. Similarly, expired as "having lost validity" (as in grocery goods) doesn't necessarily mean death. Some lexicographers claim that no synonyms have exactly the same meaning (in all contexts or social levels of language) because etymology, orthography, phonic qualities, ambiguous meanings, usage, etc. make them unique. However, many people feel that the synonyms they use are identical in meaning for all practical purposes. Different words that are similar in meaning usually differ for a reason: feline is more formal than cat; long and extended are only synonyms in one usage and not in others, such as a long arm and an extended arm. Synonyms are also a source of euphemisms. The purpose of a thesaurus is to offer the user a listing of similar or related words; these are often, but not always, synonyms. In a way, hyponyms are similar to synonyms. In contrast, antonyms (an opposite pair) would be:
- dead and alive (compare to synonyms: dead and deceased)
- near and far (compare to synonyms: near and close)
- war and peace (compare to synonyms: war and armed conflict)
- tremendous and awful (compare to synonyms: tremendous and remarkable) In biology, synonym is used with a closely defined meaning, different for animals and plants, see synonym (zoology) and synonym (botany).

Genetics

Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. The word genetics was first applied to describe the study of inheritance and the science of variation by English scientist William Bateson in a letter to Adam Sedgwick, dated April 18, 1905. Humans began applying knowledge of genetics in prehistory with the domestication and breeding of plants and animals. In modern research, genetics provides important tools for the investigation of the function of a particular gene, e.g., analysis of genetic interactions. Within organisms, genetic information generally is carried in chromosomes, where it is represented in the chemical structure of particular DNA molecules. Genes encode the information necessary for synthesizing the amino-acid sequences in proteins, which in turn play a large role in determining the final phenotype of the organism. In diploid organisms, a dominant allele on one chromosome will mask the expression of a recessive gene on the other. The phrase to code for is often used to mean a gene contains the instructions about how to build a particular protein, as in the gene codes for the protein. The "one gene, one protein" concept is now known to be simplistic. For example, a single gene may produce multiple products, depending on how its transcription is regulated. Genes code for the nucleotide sequences in mRNA, tRNA and rRNA, required for protein synthesis. Genetics determines much (but not all) of the appearance of organisms, including humans, and possibly how they act. Environmental differences and random factors also play a part. Monozygotic ("identical") twins, a clone resulting from the early splitting of an embryo, have the same DNA, but different personalities and fingerprints. Genetically-identical plants grown in colder climates incorporate shorter and less-saturated fatty acids to avoid stiffness.

History

In his paper "Versuche uber Pflanzenhybriden" ("Experiments in Plant Hybridization"), presented in 1865 to the Brunn Natural History Society, Gregor Mendel traced the inheritance patterns of certain traits in pea plants and showed that they could be described mathematically. Although not all features show these patterns of Mendelian inheritance, his work suggested the utility of the application of statistics to the study of inheritance. Since that time many more complex forms of inheritance have been demonstrated. The significance of Mendel's work was not understood until early in the twentieth century, after his death, when his research was re-discovered by other scientists working on similar problems. Mendel did not understand the nature of inheritance. We now know that some heritable information is carried in DNA. (Retroviruses, including influenza, oncoviruses and HIV, and many plant viruses, carry information as RNA.) Manipulation of DNA can in turn alter the inheritance and features of various organisms.

Timeline of notable discoveries

:1859 Charles Darwin publishes The Origin of Species :1865 Gregor Mendel's paper, Experiments on Plant Hybridization :1903 Chromosomes are discovered to be hereditary units :1905 British biologist William Bateson coins the term "genetics" in a letter to Adam Sedgwick :1910 Thomas Hunt Morgan shows that genes reside on chromosomes :1913 Alfred Sturtevant makes the first genetic map of a chromosome :1918 Ronald Fisher publishes On the correlation between relatives on the supposition of Mendelian inheritance - the modern synthesis starts. :1913 Gene maps show chromosomes containing linear arranged genes :1927 Physical changes in genes are called mutations :1928 Frederick Griffith discovers a hereditary molecule that is transmissible between bacteria (see Griffiths experiment) :1931 Crossing over is the cause of recombination (see Barbara McClintock and cytogenetics) :1941 Edward Lawrie Tatum and George Wells Beadle show that genes code for proteins; see the original central dogma of genetics :1944 Oswald Theodore Avery, Colin McLeod and Maclyn McCarty isolate DNA as the genetic material (at that time called transforming principle) :1950 Erwin Chargaff shows that the four nucleotides are not present in nucleic acids in stable proportions, but that some general rules appear to hold (e.g., that the amount of adenine, A, tends to be equal to that of thymine, T). Barbara McClintock discovers transposons in maize :1952 The Hershey-Chase experiment proves the genetic information of phages (and all other organisms) to be DNA :1953 DNA structure is resolved to be a double helix by James D. Watson and Francis Crick, with the help of Rosalind Franklin :1956 Jo Hin Tjio and Albert Levan established the correct chromosome number in humans to be 46 :1958 The Meselson-Stahl experiment demonstrates that DNA is semiconservatively replicated :1961 The genetic code is arranged in triplets :1964 Howard Temin showed using RNA viruses that Watson's central dogma is not always true :1970 Restriction enzymes were discovered in studies of a bacterium, Haemophilius influenzae, enabling scientists to cut and paste DNA :1977 DNA is sequenced for the first time by Fred Sanger, Walter Gilbert, and Allan Maxam working independently. Sanger's lab complete the entire genome of sequence of Bacteriophage Φ-X174;. :1983 Kary Banks Mullis discovers the polymerase chain reaction enabling the easy amplification of DNA :1985 Alec Jeffreys discovers genetic finger printing. :1989 The first human gene is sequenced by Francis Collins and Lap-Chee Tsui, it encodes the CFTR protein, defects in this gene cause cystic fibrosis :1995 The genome of Haemophilus influenzae is the first genome of a free living organism to be sequenced :1996 Saccharomyces cerevisiae is the first eukaryote genome sequence to be released :1998 The first genome sequence for a multicellular eukaryote, C. elegans is released :2001 First draft sequences of the human genome are released simultaneously by the Human Genome Project and Celera Genomics. :2003 (14 April) Successful completion of Human Genome Project with 99% of the genome sequenced to a 99.99% accuracy [http://www.genoscope.cns.fr/externe/English/Actualites/Presse/HGP/HGP_press_release-140403.pdf]

Areas of genetics

Classical genetics

:Main articles: Classical genetics, Mendelian inheritance Classical genetics consists of the techniques and methodologies of genetics that predate the advent of molecular biology. After the discovery of the

Heredity

Biology

History of heredity in biology

Sociology

External links

Parent

Aspects of parenting

Parenting Methods and Practices

Pregnancy and the early years

During infancy

School years

Assistance

Observers

Parenting assessment

See also

External links

Offspring

Gene

Overview

Properties of genes

Types of genes

Human gene nomenclature

Typical numbers of genes in an organism

Chemistry and function of genes

Chemical structure of a gene

Expression of molecular genes

Mutations and evolution

History

Evolutionary concept of gene

See also

References

External links

Inheritance

See also

Custom

Law

Legal traditions

Civil law

Common law

Customary law

Religious law

Bodies of law

Private law

Public law

Procedural law

International law

Philosophy of law

Anthropology of law

History

Practice of law

See also

Further reading

External links

Biology

Principles of biology

Universality: Biochemistry, cells, and the genetic code

Evolution: The central principle of biology

Diversity: The variety of living organisms

Continuity: The common descent of life

Homeostasis: Adapting to change

Interactions: Groups and environments

Scope of biology

Structure of life

Physiology of organisms

Diversity and evolution of organisms

Classification of life

Interactions of organisms

History of the word "biology"

History

Related topics

External links

Further reading

Synonym

See also

Genetics

History

Timeline of notable discoveries

Areas of genetics

Classical genetics