Me and My Family

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

chromosome

structure in a cell's nucleus that contains hereditary material

gene

A segment of DNA on a chromosome that codes for a specific trait

base pairing

principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine

allele

one of a number of different forms of a gene

gamete

a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

sperm

male gamete

ovum

female gamete

zygote

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

fertilisation

The fusion of 2 [haploid] gametes to form a [diploid] zygote.

genotype

An organism's genetic makeup, or allele combinations.

phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

haploid

An organism or cell having only one complete set of chromosomes.

diploid

An organism or cell having two sets of chromosomes or twice the haploid number

homologous chromosomes

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.

heterozygous

An organism that has two different alleles for a trait

homozygous recessive

Both alleles (factors) for a trait are the same and recessive (aa)

homozygous dominant

Both alleles (factors) for a trait are the same and dominant (AA)

karyotype

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

point mutation

gene mutation in which a single base pair in DNA has been changed

chromosomal mutation

A change in the chromosome structure, resulting in new gene combinations.

somatic cells

Any cells in the body other than reproductive cells

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms

nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.