Gene Interaction

Question 1

A phenotype can be influenced by __ if not __ of the genes that an organism posses

Answer 1

Many if not most if the genes an organism posseses

Question 2

Two ways that genes can interact

Answer 2

1. Interactions between alleles of the same gene
2. Interactions berween two or more different genes

Question 3

Genes are long stretches of DNA that comprise many opportunities for ___

Answer 3

Mutation

Question 4

With complete dominance, this intermediate level will be sufficient, resulting in Wild Type

Why?

Answer 4

Happlosufficient

With Complete Dominance there is enough gene activity in the heterozygote

Question 5

___ occurs when one Wild Type copy of a gene is insufficient

Why?

Answer 5

Happloinsufficiency

There is not enough gene activity in the heterozygote

Question 6

What is a dominant negative?

Answer 6

It does not function properly and it impairs the wild type allele

Question 7

What do heterzygotes exhibit in incomplete dominance?

Answer 7

They exhibit an intermediate phenotype

Question 8

What is codominance?

Answer 8

Heterzygote exhibits the phenotypes associated with both alleles of a gene

Question 9

What is a lethal allele?

Answer 9

Capable of causing death of an organism

Question 10

What are essential genes?

Answer 10

Genes that without which an organism dies

Question 11

What are conditional essential genes?

Answer 11

Genes that are essential in some individuals but not others.

Question 12

Peliotropic:

Answer 12

An allele that affects several properties of an organism

Question 13

Temperature sensitive mutations:

Answer 13

These are heat sensitive alleles

Question 14

Permissive temperature:

Answer 14

ts mutants exhibit wild type phenotype

Question 15

Restrictive temperature:

Answer 15

ts mutants exhibit mutant phenotype

Question 16

Penetrance:

Answer 16

The percentage of individuals with a given allele who exhibit the phenotype associated with that allele.

Question 17

Incomplete penetrance:

Answer 17

When penetrance is less than 100%

Question 18

Expressivity:

Answer 18

The intensity of the phenotype resulting from a given mutation.

Question 19

Variable expressivity:

Answer 19

When the severity of the mutant phenotype varies across individuals

Question 20

Factors that influence expressivity(5)

Answer 20

Environment

Alleles at the same gene

Genetic variation in other interacting genes

Stochastic factors

Mutant phenotype is subtle, making it difficult to measure

Question 21

Auxotrophic mutation:

Answer 21

Only grows if fed a specific metabolite

Question 22

Beadle and Tatum proposed that genetic results reflected the existence of a ___ ___

Answer 22

Biochemical pathway

Question 23

Genes encode proteins which in turn __ ___ __

Answer 23

Perform some function

Question 24

How many pathways do genes function in?

Answer 24

3

Question 25

What are the 3 pathways that genes function in?

Answer 25

Biosynthetic

Signal Transduction

Developmental

Question 26

Biosynthetic pathway:

Answer 26

Generation and interconversion of metabolic products

Question 27

Signal transduction pathway:

Answer 27

A cascade that ultimately influences the transcription of specific genes in response to a particular cue

Question 28

Developmental pathway:

Answer 28

Pathways that underlie the steps in a zygote becoming an adult organism

Question 29

Mutations in different genes will typically result in a ___ ___ ___ or ___

Answer 29

wild type phentotype or complementation

Question 30

If mutations occur in the same gene it is ___ that they will complement each other.

Why?

Answer 30

unlikely

Because both copies are broken

Question 31

What happens when mutations are in different genes that reside in the same pathway?

Answer 31

Mutations in the same pathway results in a 9:7 ratio

Question 32

Epistasis:

Answer 32

When the phenotypes of double mutants depart from expectations based on single mutants.

Question 33

Recessive epistasis:

Answer 33

When the recessive allele of one gene masks the effects of either allele at the second gene

Question 34

Dominant epistasis:

Answer 34

When the dominant allele of one gene masks the effects of the either allele at the second gene

Question 35

Suppressors:

Answer 35

A mutant allele of one gene that reverses the effect of a mutation in another gene, resulting in a wild-type or near wild type phenotype

Question 36

Modifiers:

Answer 36

Mutations at a second locus that change the degree of expression of a mutation at a first locus.

Question 37

Synthetic lethality:

Answer 37

Crossing two viable single mutants produces a lethal combination of two mutations