Appendix:Glossary of genetics

This is a glossary of genetics.

A

 * adenine : A base, $$C_5H_5N_5$$, found in certain glands and tissues, which pairs with thymine in DNA and uracil in RNA.


 * allele : One of a number of alternative forms of the same gene occupying a given position on a chromosome.

C

 * chromosome : A structure in the cell nucleus that contains DNA, histone protein, and other structural proteins.


 * codon : A sequence of three adjacent nucleotides, which encode for a specific amino acid during protein synthesis, or translation.


 * cytosine : A base, $$C_4H_5N_3O$$, which pairs with guanine in DNA and RNA.

D

 * diploid : Of a cell, having a pair of each type of chromosome, one of the pair is derived from the ovum and the other from the spermatozoon. See also haploid.


 * DNA : Deoxyribonucleic acid, the genetic material of nearly all forms of life.


 * dominant : Of an allele, determining the trait when paired with a recessive one.

G

 * gamete : A reproductive cell (male (sperm) or female (egg)) that has only half the usual number of chromosomes.


 * gene : A unit of heredity; a segment of DNA or RNA that is transmitted from one generation to the next, and that carries genetic information such as the sequence of amino acids for a protein.


 * gene pool : The complete set of unique alleles that would be found by inspecting the genetic material of every living member of a species or population.


 * genome : The complete DNA content of an organism, typically expressed in number of basepairs.


 * genotype : The combination of alleles, situated on corresponding chromosomes, that determines a specific trait of an individual, such as "Aa" or "aa".


 * guanine : A substance first obtained from guano; it is a nucleic base and pairs with cytosine in DNA and RNA.

H

 * haploid : Of a cell having a single set of unpaired chromosomes, such as a gamete. See also diploid.


 * heterozygote : A diploid individual that has different alleles at one or more genetic loci.


 * homozygote : A diploid individual that has equal alleles at one or more genetic loci.

M

 * mutation : Any heritable change in the base-pair sequence of genetic material, namely DNA (or RNA in the case of some viruses).

N

 * nucleic acid : Any acidic, chainlike biological macromolecule consisting of multiply repeat units of phosphoric acid, sugar and purine and pyrimidine bases.


 * nucleobase : The base of a nucleic acid, which include thymine, uracil and adenine, cytosine and guanine.


 * nucleotide : The monomer comprising DNA or RNA biopolymer molecules.

O

 * ovum : The female gamete in animals; the egg.

R

 * recessive : Of an allele, yielding to the choice made by the dominante alelle.


 * recombination : The formation of genetic combinations in offspring that are not present in the parents.


 * RNA : Ribonucleic acid.

S

 * spermatozoon : The reproductive cell or gamete of the male, carried in semen, that fertilizes the ovum to produce the zygote. Synonyms: sperm cell.

T

 * thymine : A base, $$C_5H_6N_2O_2$$, obtained by applying sulphuric acid to thymic acid; it pairs with adenine in DNA.

U

 * uracil : One of the bases of RNA which pairs with adenine and is symbolised by U.

Z

 * zygote : A fertilized egg cell.