BIO - Genetic Expression Notes

Genetic Expression & Punnett Squares

Genes -

• specific portions of DNA that determine hereditary characteristics

• carry traits that can pass from one generation to the next

Alleles -

• different molecular forms of a gene

• each parent passes on one allele for each trait to offspring

• each offspring has two alleles for each trait

• expression of physical characteristic depends on the genes from each parent

• the physical expression of the traits

• does not necessarily reveal combination of alleles

  • EX :

    • Brown eyes

    • Blue eyes

Phenotype -

• term used for the combination of alleles inherited from the parents

  • EX :

    • Bb or BB (Brown eyes)

    • bb (blue eyes)

Genotype -

Genotype vs Phenotype

• trait that is typically masked by the dominant gene.

• REQUIRES 2 recessive genes to express itself

Recessive -

• trait that will most likely express itself

  • EX : Brown hair is dominant over blonde hair

Dominant -

Dominant vs Recessive