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 Sedgewick, dated April 18, 1905.

Areas of genetics

Classical genetics

:Main articles: Classical genetics, Mendelian inheritance

Related Topics:
Classical genetics - Mendelian inheritance

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Classical genetics consists of the techniques and methodologies of genetics that predate the advent of molecular biology. After the discovery of the genetic code and such tools of cloning as restriction enzymes, the avenues of investigation open to geneticists were greatly broadened. Some classical genetic ideas have been supplanted with the mechanistic understanding brought by molecular discoveries, but many remain intact and in use, such as Mendel's laws. Patterns of inheritance still remain a useful tool for the study of genetic diseases.

Related Topics:
Genetics - Molecular biology - Genetic code - Cloning - Restriction enzyme - Mendel's laws - Genetic disease

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Molecular genetics

Molecular genetics builds upon the foundation of classical genetics but focuses on the structure and function of genes at a molecular level. Molecular genetics employs the methods of both classical genetics (such as hybridization) and molecular biology. It is so-called to differentiate it from other sub fields of genetics such as ecological genetics and population genetics. An important area within molecular genetics is the use of molecular information to determine the patterns of descent, and therefore the correct scientific classification of organisms: this is called molecular systematics.

Related Topics:
Genes - Molecular - Hybridization - Molecular biology - Ecological genetics - Population genetics - Scientific classification - Molecular systematics

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The study of inherited features not strictly associated with changes in the DNA sequence is called epigenetics.

Related Topics:
DNA - Epigenetics

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Some take the view that life can be defined, in molecular terms, as the set of strategies which RNA polynucleotides have used and continue to use to perpetuate themselves. This definition grows out of work on the origin of life, specifically the RNA world hypothesis.

Related Topics:
Life - Molecular - RNA - Origin of life - RNA world hypothesis

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Clinical Genetics

Physicians who are trained as geneticists diagnose, treat, and counsel patients with genetic disorders or syndromes.

Related Topics:
Physician - Genetic disorders - Syndrome

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These doctors are typically trained in a genetics residency or fellowship. Many are pediatricians, but some are not.

Related Topics:
Residency - Fellowship - Pediatrician

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Population, quantitative and ecological genetics

:Main articles: Population genetics, Quantitative genetics, Ecological genetics

Related Topics:
Population genetics - Quantitative genetics - Ecological genetics

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Population, quantitative and ecological genetics are all very closely related subfields and also build upon classical genetics (supplemented with modern molecular genetics). They are chiefly distinguished by a common theme of studying populations of organisms drawn from nature but differ somewhat in the choice of which aspect of the organism on which they focus. The foundational discipline is population genetics which studies the distribution of and change in allele frequencies of genes under the influence of the four evolutionary forces: natural selection, genetic drift, mutation and migration. It is the theory that attempts to explain such phenomena as adaptation and speciation.

Related Topics:
Population - Allele frequencies - Natural selection - Genetic drift - Mutation - Migration - Adaptation - Speciation

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The related subfield of quantitative genetics, which builds on population genetics, aims to predict the response to selection given data on the phenotype and relationships of individuals. A more recent development of quantitative genetics is the analysis of quantitative trait loci. Traits that are under the influence of a large number of genes are known as quantitative traits, and their mapping to a location on the chromosome requires accurate phenotypic, pedigree and marker data from a large number of related individuals.

Related Topics:
Selection - Phenotype - Quantitative trait loci - Chromosome

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Ecological genetics again builds upon the basic principles of population genetics but is more explicitly focused on ecological issues. While molecular genetics studies the structure and function of genes at a molecular level, ecological genetics focuses on wild populations of organisms, and attempts to collect data on the ecological aspects of individuals as well as molecular markers from those individuals.

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Genomics

A more recent development is the rise of genomics, which attempts the study of large-scale genetic patterns across the genome for (and in principle, all the DNA in) a given species. Genomics depends on the availability of whole genome sequences, and computational tools developed in the field of bioinformatics for analysis of large set of data.

Related Topics:
Genomics - Genome - Bioinformatics

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Closely-related fields

The science which grew out of the union of biochemistry and genetics is widely known as molecular biology.

Related Topics:
Biochemistry - Molecular biology

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The term "genetics" is often widely conflated with the notion of genetic engineering, where the DNA of an organism is modified for some kind of practical end, but most research in genetics is aimed at understanding and explaining the effect of genes on phenotypes and in the role of genes in populations (see population genetics and ecological genetics), rather than genetic engineering.

Related Topics:
Genetic engineering - Population genetics - Ecological genetics

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