Lecture #12

Question 1

What is the most common allele and how is it identified?

Answer 1

the wild type, usually identified with a superscript +

Question 2

What is a polymorphism?

Answer 2

Any allele found at appreciable frequencies (at least 1%) in the population

Question 3

What alleles are considered mutant alleles?

Answer 3

any alleles other than the wild type or any polymorphisms

Question 4

What are 5 factors that mendel did not account for in his expeirements?

Answer 4

genes have more than 2 alleles, different alleles may affect the phenotype in different ways, a single gene may control several traits, multiple genes may control a single trait, environmental factors can influence phenotypes

Question 5

What is incomplete dominance?

Answer 5

When the heterozygotes have a phenotype of the two homozygotes mixed

Question 6

Why may incomplete dominance happen?

Answer 6

the homozygotes have twice as much enzyme as heterozygotes

Question 7

What is co-dominance?

Answer 7

When the phenotype expresses the phenotype of both homozygotes

Question 8

What is an allelic series?

Answer 8

describes the dominance hierarchy of multiple alleles

Question 9

What is the genotype for blood type A?

Answer 9

I^A I^A or I^A i

Question 10

What is the genotype for blood type B?

Answer 10

I^B I^B or I^B i

Question 11

What is the genotype for AB blood type?

Answer 11

I^A I^B

Question 12

What is the genotype for O blood type?

Answer 12

ii

Question 13

What is penetrance?

Answer 13

the percentage of individuals having a particular genotype that expresses the expected phenotype

Question 14

What is expressivity?

Answer 14

the degree to which a character is expressed

Question 15

What is incomplete penetrance?

Answer 15

When individuals do not express a trait even though they have the genotype

Question 16

What is a lethal allele?

Answer 16

causes death at an early stage of development, and so some genotypes may not appear among the progeny

Question 17

What is the results of a null mutation in either the cyclin gene or the CDK gene?

Answer 17

it will inhibit the phosphorylation of the target protein and generate the same mutant phenotype

Question 18

What are discontinuous characteristics?

Answer 18

relatively few phenotypes

Question 19

What are polygenic characteristics?

Answer 19

characteristics influenced by genes at many loci

Question 20

What is a temperature sensitive allele?

Answer 20

an allele whose product is only functional at certain temperatures

Question 21

What are multifactorial charcteristics?

Answer 21

refers to the continuous characteristics that are both polygenic and influenced by environmental factors