# Appendix:Glossary of genetics

This is a glossary of genetics.

Table of Contents: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

## A

A base, ${\displaystyle C_{5}H_{5}N_{5}}$, 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, ${\displaystyle C_{4}H_{5}N_{3}O}$, 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, ${\displaystyle C_{5}H_{6}N_{2}O_{2}}$, 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.