Extensions of Mendelian Genetics

Question 1

What is a dihybrid cross?

Answer 1

A dihybrid cross describes a mating experiment between two organisms that are identically hybrid for two traits

Question 2

What is the product rule for offspring probability?

Answer 2

What happens at one gene is not linked to another
SsYy x SsYy
ss = 1/4 yy = 1/4
1/4 x 1/4 = 1/16

Question 3

What is the sum rule for offspring probability?

Answer 3

Overall probability of one or the other event occurring - not both (mutually exclusive)
AaBBCc x AaBbcc = AaBbcc
Aa = 1/2
Bb = 1/2
cc = 1/2
Total probability of AaBbcc = 1/8

Question 4

What is polymorphic ?

Answer 4

Polymorphism is the occurrence of two or more different phenotypes in the population of a species

Question 5

What is codominance?

Answer 5

Where both phenotypes exist side by side within the organism

Question 6

What are polygenic traits?

Answer 6

Phenotype controlled by many genes that have an additive effect
Characters appear continuous or quantities
Controlled by groups of genes

Question 7

How does the environment affect phenotype?

Answer 7

Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed.