Genetics Vocabulary Review

Phenotype vs. Genotype

Genotype:

● The genes/alleles

an organism has

● Examples:

○ RR
○ Ww
○ hh

Phenotype:

● The physical

appearance of an
organism

● Examples:

○ Right-handed
○ Widow’s peak
○ Cleft chin

Describing Genotypes

We describe genotypes as:

● Homozygous or heterozygous
● Dominant or recessive

Homozygous vs Heterozygous

Heterozygous:

● The 2 alleles are

DIFFERENT

● Examples

○ Hh
○ Bb

Homozygous:

● The 2 alleles are the

SAME/ identical

● Examples:

○ hh
○ HH
○ BB
○ bb

Dominant vs Recessive

Recessive:

● A genotype with 2

lowercase letters

● Examples:

○ bb
○ hh

Dominant:

● A genotype with

an UPPERCASE
letter

● Examples:

○ BB, Bb
○ HH, Hh

We can use 2 words together to describe genotypes

AA= homozygous AND dominant

aa= homozygous AND recessive

Aa= heterozygous AND dominant