Biology genetics

Alleles

They are the alternative forms of a gene. e.g. brown eyes/ blue eyes

Gene

Its a section of a chromosome that codes for a trait/ characteristic e.g. eye colour

Homozygous

Having 2 copies of the same allele e.g homozygous dominant “BB” or Homozygous recessive “bb”

Hetrozygous

Carrying 2 different forms of an allele e.g Bb

Phenotype

Is an observational trait or characteristic of an organism (what it looks like) e.g eye colour (blue, green, brown)

Genotype

A combination of alleles an organism has for a particular gene e.g brown eyes the genotype could be BB, Bb, bb

Somatic cells

Any body cell except the reproductive cells. e.g muscle cells, skin cells, blood cells, nerve cells.

Gametic cells

Reproductive cells e.g sperm and egg

Mutations in Somatic cells?

Can only affect the individual (cannot be passed to off spring)

Mutations in Gametic cells?

Can be passed onto offspring (mutations can affect next generation)

Meosis

Is the reduction divison, it halves the chromosomal number from 46 to 23

Where dos meosis occur

In the reproductive organs (testies and ovaries)

What does meosis produce?

Gametes (sperm and egg)