Chapter 12.1

Question 1

What is a hemizygous genotype

Answer 1

-when only one allele is present for a given gene

Question 2

What is codominance

Answer 2

• when more than one dominant allele exists for a gene

- >eg; blood type A and blood type B

Question 3

What is incomplete dominance

Answer 3

• when a heterozygote expresses a phenotype that is intermediate between two homozygous genotypes
• > eg; mating of a certain flowers
• > red flower + white flower= pink flower

Question 4

What is meant by the term penetrance

Answer 4

• it is a population measure
• > defined as the proportion of individuals in the population carrying the allele who are actually expressing the phenotype

-in other words, given the probability that an individual contains the genotype, they will express the phenotype

Question 5

What is meant by the term expressivity. Note whereas penetrance is a population parameter, expressivity is a more an individual characteristic

Answer 5

-varying phenotypes that are present, despite the same genotype

• if it is constant
• > then individuals with the same genotype express the same phenotype
• if it is variable
• > then individuals with the same genotype may have different phenotypes