1. Genetics Notes!

2. True-Breeding = Homozygous – having 2 alleles for a given trait that are the same (EX. Both parents gave you blue eyes); written as TT or tt (same size)
Hybrid = Heterozygous – Having 2 different alleles for a given trait (EX. Mom gave you blue eyes and dad gave you brown eyes); written as Tt
Dominant – version of an allele that always shows if present regardless of what the other allele is. Symbolized by CAPITALS (T for tall)
Recessive – version of an allele that ONLY shows if there is no dominant allele present (ie. When there are 2 recessive alleles). Symbolized by lower case (t for short)

3. 5) Genotype – 1) genetic make-up 2) which alleles are present in the DNA
3 ways to describe:
*Homozygous Dominant TT
*Heterozygous Tt (dominant shows
*Homozygous Recessive tt
6) Phenotype – physical characteristics – “We can see or detect” (EX. – tall, short, blue eyes, able to taste PTC)

4. Mothers Genotype - one spot = one allele
Punnett Squares
Mothers Genotype - one spot = one allele
Inside boxes represent Possible outcomes of genetic cases.
*Using numbers 1&2 for mother’s genotype and 3&4 for fathers
Father's alleles

5. How to do Punnett Squares
2) Place each letter of
mother's genotype over a box
1) Draw box

6. 1 2 1 2 1 2 3 4 3 4 1 2 4) Copy MG into 3) Place each letter of
boxes below each allele
3) Place each letter of
father's genotype next to box
3 4
3 4

7. 5) Copy FG into boxes
beside each allele
3 4

8. If there are multiple letters, put in alphabetical order. AaBBcc or XY
Show Dominant (T) before Recessive – Aa (never aA)