1. Genetics Vocabulary

2. Vocabulary: alleles –the different versions of a gene ex: P and p
dominant traits – the expressed form of a trait
ex: PP or Pp
recessive traits – the trait not expressed, unless two are present
ex: pp

3. Choosing your alleles:
Purple flowers are dominant to white flowers.
dominant traits –are expressed by writing the first letter of the trait as an uppercase letter
ex: purple flower - P
recessive traits –are expressed by writing the first letter of the dominant trait but as a lowercase letter
ex: white flower - p

4. Selecting Your Alleles:
Height: tall is dominant; short is recessive
Eye color: brown is dominant; green is recessive
Hair: curly is recessive; straight is dominant T t B b s S

5. More Vocabulary:
homozygous – the two alleles of a particular gene are the same ex: PP or pp
heterozygous – the two alleles of a particular gene are different ex: Pp
genotype – the set of alleles (genes) for a trait
ex: PP, Pp, pp
phenotype - the physical appearance of a trait
ex: purple flower, white flower

6. Homozygous or Heterozygous?Rr Tt ss
Hetero PP tt Yy
Homo
Hetero
Homo
Homo
Hetero

7. Genotype or Phenotype? PP Red hair Yellow seeds Rr Dimples Tt Yy ss
Short PP
Yellow seeds
Dimples Yy
Set of alleles P G G P G P G G P G

8. Practice:
For each genotype below, indicate whether it is heterozygous (He), homozygous (HO D) or (HO r)
Rr ______ HH _______
ii ______ Ww _______
For each genotype below determine what phenotypes would be possible.
Curly hair is dominant to straight hair.
Cc ________ CC _________
cc ________ He
HO D
HO r He
Curly hair
Curly hair
Straight hair

9. Practice: For each phenotype below, list the genotypes.
Remember to use the letter of the dominant
trait.
Green eyes are dominant to blue eyes.
______ green eyes _______ blue eyes
______ green eyes GG gg Gg

10. Other Terms You May See:
Homozygous = Purebred MM mm
Heterozygous = Hybrid Mm