4. A unique sequence of
DNA.
A genotype refers to the two alleles an
organism has inherited for a particular gene.
Alleles can be recessive or dominant
(More on this in a moment!)
GENOTYPE
5. An observable trait
For example, a phenotype could be:
Brown hair, AB blood type or blue eye
colour
Phenotype is a result of the
expression of one or more genes.
PHENOTYP
E
6. Only ONE allele is needed for the trait to be expressed.
DOMINANT
RECESSIVE
TWO alleles are needed for the trait to be expressed.
7. There are 4 main types of
genetic inheritance:
• Dominant
• Recessive
• Codominance
• Incomplete Dominance
8. White with brown spots is a dominant trait.
If the cow has one or two dominant alleles, it will
be white with brown spots.
DOMINANT
9. All white is a recessive trait.
If the cow has two recessive alleles, it will be
all white in colour.
RECESSIVE
10. Both alleles of a gene are distinctly expressed.
Red and white show codominance.
If a plant has both a recessive and dominant
gene, it will be red with white spots.
CODOMINANCE
11. Both alleles are partially expressed in an intermediate
phenotype.
The colour pink shows incomplete dominance.
If a plant has both a recessive and dominant
gene, it will be a mix of red and white (pink).
INCOMPLETE
DOMINANCE
