Gene Interaction

Question 1

what are the extensions/exception of Mendelian inheritance

Answer 1

sex linked traits

Question 2

what is the difference between molecular basis of inheritance

Answer 2

-dominant and recessive have phenotypic basis
-dominance is determined by protein product of alleles
-phenotype is activity of protein products

Question 3

haploinsufficient vs. haplosufficient

Answer 3

Haplosufficient: bot +/+ and +/m produce sufficient protein product for normal phenotype

Haploinsufficient: one dose of wild type(+/m) does not produce sufficient amounts of protein product for normal phenotype

Question 4

mutant allele vs wild type

Answer 4

Wild type: found in nature(normal gene)
Mutant allele: mutation of the wild type gene producing a different phenotype

Question 5

are wild type alleles typically dominant or recessive

Answer 5

dominant

Question 6

two types of functional effects of mutant alleles

Answer 6

loss of function: decrease or total loss of functional gene product

gain of function: gene product gains new function or increases wild type activity

Question 7

incomplete dominance vs co dominance

Answer 7

incomplete dominance: blending of both phenotypes
(red + white =pink)

codominance: both phenotypes are present
(red + white = red and white)

Question 8

genotype and phenotype ratio of F2 for incomplete dominance

Answer 8

genotype: 1:2:1

phenotype: 1:2:1

Question 9

genotype and phenotype ratio of F2 for codominance

Answer 9

genotype: 1:2:1

phenotype: 1:2:1

Question 10

what is the genetic explanation for C-gene system for coat color of temp sensitive extremities (ex. Siamese cats)

Answer 10

the Ch allele which is a mutation from the natural C gene is a temperature-sensitive gene that is only functional at lower temperatures(like paws, ears, and tail), but lose catalytic function at higher temperature areas

Question 11

what case can allow for dominant lethal alleles to persist in a population

Answer 11

late-onset genes that allow an affected individual to reproduce before affects begin to show
(ex. huntingtons)

Question 12

what is pleiotropy? give an example

Answer 12

it is the alteration of multiple distinct traits through the mutation of a single gene
EX: sickle cell disease due to mutation in B-globin gene

Question 13

epistasis definition

Answer 13

gene interaction resulting in altered phenotype

Question 14

what 6 modifications can modify the 9:3:3:1 ratio?

Answer 14

complementary
duplicate
dominant
recessive epistasis
dominant epistasis
dominant supression

Question 15

what can complementary analysis distinguish

Answer 15

-if mutations are on the same or different genes
-how many genes are responsible for mutations

Question 16

penetrance vs. expressivity

Answer 16

penetrance: the percentage of individuals that show some degree of expression of a mutant genotype(ex you either have penetrance or you dont)
expressivity: the range of expression of mutant phenotype
(ex a spectrum of expresivity)

Question 17

example for non-penetrance

Answer 17

-polydactyly (nonpenetrant 25-30% of the time)
-brachydactyly

Question 18

duplicate gene interaction
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 18

-15:1
-dominant alleles are redundant at either locus. as long as one is present you will have the wild-type phenotype

Question 19

dominant gene interaction
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 19

-9:6:1 dihybrid ratio
-2 genes contribute to a phenotype, homozygous dominant gives 1 phenotype(ex. disk), heterozygous gives another shape(ex. round), and homozygous recessive gives a third phenotype(e. elongated)

Question 20

recessive epistasis
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 20

-9:6:1
-recessive allele at one locus will mask the phenotypic expression of the allele at the other locus

Question 21

dominant epistasis
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 21

-12:3:1
-dominant allele at one locus overrides or masks the interaction of the other allele

Question 22

dominant suppression
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 22

-13:3
-the second allele blocks expression of the first regardless of the firsts dominance

Question 23

recessive suppressor

Answer 23

a mutant allele (the suppressor) reverses mutant affect of another gene resulting in a wild type phenotype

Question 24

complementary gene interaction
-what is the phenotypic ratio
-what is occurring to change the ratio

Answer 24

-9:7
-genes work in tandem to produce a single product(both dominant alleles must be present for dominant trait)

Question 25

how to determine with complementary analysis location of the genes

Answer 25

if wild type persists the mutations are on different genes if mutant type persists mutant alleles are on the same gene

Question 26

what does it mean to be penetrant

Answer 26

phenotype is consistent with genotype