1. Dihybrid Crosses and Polygenic Traits
The Basis of Heredity
Dihybrid Crosses and Polygenic Traits

2. Review pg #1

3. Evidence of Independent Assortment
A cross that involves with two independent traits that are present in alternate forms
Mendel crossed garden peas – first pure (homozygous) two dominant and two recessive
2nd Law – genes that are located on different chromosomes assort independently
Mendel’s 2nd Law:
Law of Independent
Assortment

4. 1st Law – law of segregation
The alleles of both of these
genes will segregate during
meiosis

5. Probability and Dihybrid Crosses
Sample Exercise 1 pg
Probability that two outcomes will occur at the same time

6. 9:3:3:1
F1 progeny self-fertilizes into F2 generation. Mendel examined the phenotypes produced.
A Punnett square analysis of the genotype confirms Mendel’s theory about independent assortment.

7. Harry Potter and Dragon Genetics