chapter 4 part 2

Question 1

example of pleiotropic genes

Answer 1

-sickle cell disease (autosomal recessive) caused by lack of B-globin gene
-many red blood cells of ppl w/ sickle cell take on a sickle shape and cause LOTS of problems & complications

Question 1

pleitropy

Answer 1

alteration of multiple distinct traits by a mutation in a single gene
-many affects
-sickle cell anemia ( many different complications)

Question 2

gene interaction

Answer 2

many genes working together to produce one trait or a group of related traits

Question 3

what both involve genes working together through a multi-step process with intermediate products?

Answer 3

-catabolic & anabolic pathways

Question 4

anabolic pathways

Answer 4

involve biosynthesis of complex comounds

Question 5

catabolic pathways

Answer 5

involve degradation of complex compounds

Question 6

what else involves interaction of multiple genes?

Answer 6

-signal transduction pathways & developmental pathways

Question 7

what is epistasis?

Answer 7

One gene’s alleles can change or block the expression of another gene’s alleles.
-Genes in a multi-step process work together to create the final product.
-mutation of one gene in a pathway can stop the production of the end product

Question 8

what does epistasis literally mean

Answer 8

“stand upon”

Question 9

what can gene interaction lead to?

Answer 9

-altered phenotypic ratios of wild type & mutant progeny

Question 10

what do different patters of epistatic reactions result from?

Answer 10

different ways gene products interact in pathways

Question 11

where is epistasis readily dedectied?

Answer 11

among progeny of dihybird crosses involving genes with both dominant & recessive alleles

Question 12

what does the 9:3:3:1 ratio tell us?

Answer 12

that there is an absence of epistasis- the genes of not interact to change the expression of one another

Question 13

complementary gene interaction ratio

Answer 13

9:7

Question 14

complementary gene crossing

Answer 14

-crossed two pure-breeding strains of white flowered sweet peas
-all the F1 were purple flowered
-the F1 x F2 cross yielded an F2:9/16 purple 7/16

Question 15

when genes work in tandem to produce a single product

Answer 15

-complementary gene interaction
-the example of the white flowered sweet peas recognized that the two genes must interact to produce the overall flower color

Question 16

duplicate gene action ratio

Answer 16

15:1

Question 17

genes in a redundant system have a _______ ______ ________

Answer 17

duplicate gene
-they encode the same product, or they encode products that have the same effect in a pathway or compensatory pathways

Question 18

dominant gene interaction ratio

Answer 18

9:6:1 dihybrid ratio

Question 19

recessive epistasis ration

Answer 19

9:3:4

Question 20

recessive epistasis

Answer 20

homozygosity for the recessive alleles at one locus will mask the phenotypic expression of the alleles at a second locus

Question 21

dominant epistasis ratio

Answer 21

12:3:1

Question 22

dominant epistasis

Answer 22

-a dominant allele at one locus will mask the phenotypic expression of the alleles at a second locus

Question 23

dominant suppression ratio

Answer 23

13:3

Question 24

dominant suppression

Answer 24

a dominant allele at one locus completely suppresses the phenotypic expression of the alleles at a second locus

Question 25

genetic complementation analysis

Answer 25

prefromed by mating two pure-breeding mutants for similar mutant phenotypes & observing phenotypes in the F1 generations

Question 26

if phenotypically wild type offspring are obtained

Answer 26

-the mutations in the parents must be in two different genes
-complementation has occured

Question 27

if phenotypically mutant offspring are obtained

Answer 27

-the mutations in the parents must be in the same gene
-complementation has not occured (failed to complement)

Question 28

genetic heterogeneity

Answer 28

described conditions when mutations in different genes can produce the same or very similar phenotypes