Chapter 4- Extensions of Mendelian Genetics

Question 1

gene interaction

Answer 1

a single phenotype is affected by more than one set of genes

Question 2

X-linkage

Answer 2

the pattern of inheritance resulting from genes located on the X chromosome

Question 3

allele

Answer 3

alternative form of gene

Question 4

wild-type

Answer 4

normal and often dominant

Question 5

loss of function mutation

Answer 5

mutations that produce alleles encoding proteins with reduced or no function of wild type

Question 6

null allele

Answer 6

a mutant allele that produces no functional gene product. usually inherited as a recessive gene product

Question 7

gain of function mutation

Answer 7

a type of mutation in which the gene product takes on a new function and produces a phenotype different from that of the normal allele and from any loss of function alleles

Question 8

oncogene

Answer 8

a gene whose activity promotes uncontrolled proliferation in eukaryotic cells. usually derived from proto-oncogens.

Question 9

neutral mutations

Answer 9

a mutation with no perceived immediate adaptive significance or phenotypic effect

Question 10

incomplete dominance

Answer 10

expressing a heterozygous phenotype that is distinct from the phenotype of either homozygous parent. aka partial dominance

Question 11

Tay-sachs Disease

Answer 11

homozygous recessive; fatal lipid storage disorder

Question 12

hexosaminidase A

Answer 12

enzyme involved in lipid metabolism

Question 13

threshold effect

Answer 13

normal phenotypic expression occurs once a certain level of gene product is obtained

Question 14

codominance

Answer 14

joint expression of both alleles in a heterozygote

Question 15

codominant inheritance is characterized by:

Answer 15

distinct expression of the gene products of both alleles