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GeneticsFrom Wikipedia, the free encyclopedia

Genetics (from Ancient Greek genetikos, "genitive" and that from genesis, "origin"),[1][2][3] a

discipline of biology, is the science of genes, heredity, and variation in living organisms.[4][5]

Genetics deals with the molecular structure and function of genes, gene behavior in the context of a cell or organism

(e.g. dominance and epigenetics), patterns of inheritance from parent to offspring, and gene distribution, variation

and change in populations, such as through Genome-Wide Association Studies. Given that genes are universal to

living organisms, genetics can be applied to the study of all living systems, from viruses and bacteria, through plant

and domestic animals, to humans (as in medical genetics).

The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop

plants and animals through selective breeding. However, the modern science of genetics, which attempts to

understand the process of inheritance, only began with the work of Gregor Mendel in the mid-19th century.[6]

Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits by way of

discrete units of inheritance, which are now called genes.

Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides

the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double

stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template fo

creating a new partner strand. This is the physical method for making copies of genes that can be inherited.

The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins

the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This relationship between

nucleotide sequence and amino acid sequence is known as the genetic code. The amino acids in a protein determin

how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein's function. Proteins

carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein'samino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a

whole.

Although genetics plays a large role in the appearance and behaviorof organisms, it is the combination of genetics

with what an organism experiences that determines the ultimate outcome. For example, while genes play a role in

determining an organism's size, the nutrition and health it experiences after inception also have a large effect.

Contents

1 History

1.1 Mendelian and classical genetics

1.2 Molecular genetics

2 Features of inheritance

2.1 Discrete inheritance and Mendel's laws

2.2 Notation and diagrams

2.3 Interactions of multiple genes

3 Molecular basis for inheritance

http://en.wikipedia.org/wiki/Genetics#Molecular_basis_for_inheritancehttp://en.wikipedia.org/wiki/Genetics#Discrete_inheritance_and_Mendel.27s_lawshttp://en.wikipedia.org/wiki/Genetics#Discrete_inheritance_and_Mendel.27s_lawshttp://en.wikipedia.org/wiki/Genetics#Features_of_inheritancehttp://en.wikipedia.org/wiki/Genetics#Mendelian_and_classical_geneticshttp://en.wikipedia.org/wiki/Genetics#Historyhttp://en.wikipedia.org/wiki/Genetic_codehttp://en.wikipedia.org/wiki/Translation_(genetics)http://en.wikipedia.org/wiki/Amino_acidhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/DNA_replicationhttp://en.wikipedia.org/wiki/Countable_sethttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Selective_breedinghttp://en.wikipedia.org/wiki/Genetics#cite_note-Weiling-6http://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Dominance_(genetics)http://en.wikipedia.org/wiki/Epigeneticshttp://en.wikipedia.org/wiki/Molecular_Geneticshttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Genetics#Molecular_basis_for_inheritancehttp://en.wikipedia.org/wiki/Genetics#Interactions_of_multiple_geneshttp://en.wikipedia.org/wiki/Genetics#Notation_and_diagramshttp://en.wikipedia.org/wiki/Genetics#Discrete_inheritance_and_Mendel.27s_lawshttp://en.wikipedia.org/wiki/Genetics#Features_of_inheritancehttp://en.wikipedia.org/wiki/Genetics#Molecular_geneticshttp://en.wikipedia.org/wiki/Genetics#Mendelian_and_classical_geneticshttp://en.wikipedia.org/wiki/Genetics#Historyhttp://en.wikipedia.org/wiki/Healthhttp://en.wikipedia.org/wiki/Nutritionhttp://en.wikipedia.org/wiki/Human_heighthttp://en.wikipedia.org/wiki/Genetic_codehttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Amino_acidhttp://en.wikipedia.org/wiki/Translation_(genetics)http://en.wikipedia.org/wiki/DNA_replicationhttp://en.wikipedia.org/wiki/Nucleotideshttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Countable_sethttp://en.wikipedia.org/wiki/Genetics#cite_note-Weiling-6http://en.wikipedia.org/wiki/Gregor_Mendelhttp://en.wikipedia.org/wiki/Selective_breedinghttp://en.wikipedia.org/wiki/Medical_geneticshttp://en.wikipedia.org/wiki/Humanhttp://en.wikipedia.org/wiki/Domestic_animalshttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Population_geneticshttp://en.wikipedia.org/wiki/Epigeneticshttp://en.wikipedia.org/wiki/Dominance_(genetics)http://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Molecular_Geneticshttp://en.wikipedia.org/wiki/Genetics#cite_note-Hartl_and_Jones-5http://en.wikipedia.org/wiki/Genetics#cite_note-griffiths2000sect60-4http://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Genetic_variationhttp://en.wikipedia.org/wiki/Heredityhttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Biologyhttp://en.wikipedia.org/wiki/Genetics#cite_note-3http://en.wikipedia.org/wiki/Genetics#cite_note-2http://en.wikipedia.org/wiki/Genetics#cite_note-1http://en.wikipedia.org/wiki/Ancient_Greek