BIOL201 Ch12.3 | Dihybrid Cross and Gene Linkage

Biology 201 Lecture Video Covering Chapter 12.3 Laws of Inheritance of OpenStax Biology Summary:

Mendel used his data to form several rules or laws of inheritance 
Pairs of Unit Factors – genes are discrete units each parent has 2 alleles and gives 1 allele
Law of Dominance 
Law of Segregation – genes segregate equally into gametes. (1:2:1 genotype ratio) 
Law of Independent Assortment – genes do not influence inheritance of one another. 
EXCEPT if they are linked on a chromosome!  

Dihybrid cross for two unlinked traits 
F2 9:3:3:1 Phenotype Ratio
F2 9 Dom Dom : 3 Dom Rec : 3 Rec Dom : 1 Rec Rec phenotype ratio 
Deviation from this could indicate linkage or epistasis 

Linkage – two genes located close together on the same chromosome 
Only recombination can form new combinations of alleles 

Epistasis – the expression of one gene impacts the expression of another 

Lecture Presented by Dr. Ben Burrows for the College of Eastern Idaho
Course BIOL 201 Intro Biology
#biology #genetics #chromosomes