Genetics

gene

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

allele

Different forms of a gene

Trait

A characteristic that an organism can pass on to its offspring through its genes.

multiple alleles

three or more forms of a gene that code for a single trait

Heterozygous

An organism that has two different alleles for a trait

Homozygous

An organism that has two identical alleles for a trait

Recessive

An allele that is masked when a dominant allele is present

Genotype

genetic makeup of an organism

Phenotype

An organism's physical appearance, or visible traits.

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

fertilization

where two sex cells fuse to form a zygote

Nitrogenous base

nucleus

organelle that controls the cells activities and stores the genetic information

discontinuous variation

variation where there is not a range and it can be put into groups eg. eye colour, ear lobes and is not influenced by environment

continuous variation

variation that as a range eg height weight and can be influenced by environment and genetics

variation

genetic differences within a species

gene

section of dna that codes for a specific characteristic

Base pairing rule

Adenine -> thymine
cytosine -> guanine

Sex Cells

Gametes, only have 23 chromosomes

Mutation

Change in the dna

AA

Homozygous dominant

XY

Male

phenotype

Physical expression of a genotype