Mendel's Law Notes Pt. 2

Question 1

Epistasis

Answer 1

from the effects of an allele at one gene
masking the effects of another gene

an interaction between genes where one gene can override the effects of another.

Question 2

Masking allele in epistasis

Answer 2

epistatic to the other gene

Question 3

Gene that is masked

Answer 3

hypostasis to the other allele

Question 4

Is Epistasis recessive or dominant?

Answer 4

It can be both

Question 5

Recessiveness in Epistasis

Answer 5

allele must be homozygous recessive (bb)

Question 6

Dominance in Epistasis

Answer 6

one copy of an allele masks another (Aa)

Question 7

Recessive epistasis Ratio

Answer 7

9:3:4
- Genotype ee masks the effect of all B genotypes

Question 8

Dihybrid Cross Ratio

Answer 8

9:3:3:1

Question 9

Complementary Gene Action Ratio

Answer 9

9:7

Question 10

Dominant Epistatsis Ratio

Answer 10

12:3:1
- The dominant allele of one gene masks both alleles of another gene

Question 11

Dominant Suppression Ratio

Answer 11

13:3

Question 12

Redundant Genes Ratio

Answer 12

15:1
- only one dominant allele is needed

Question 13

Does the same genotype always produce the same phenotype?

Answer 13

No, individuals have different alleles
- some dominant and some recessive
- the combination of which results in different phenotypes.

Question 14

Penetrance

Answer 14

is the percentage of
individuals with a particular genotype that show the expected phenotype
* Can be complete (100%) or incomplete

Question 15

Expressivity

Answer 15

is the degree or intensity with which a particular genotype is expressed in a phenotype

Question 16

Unvarying expressivity

Answer 16

The phenotype appears the same in all individuals.

Question 17

Variable expressivity

Answer 17

The phenotype varies in intensity or form among individuals.

Question 18

Environmental effects on a phenotype

Answer 18

• temperature
• can regulare gene expression and phenotype predications
• also, phenocopy

Question 19

Conditional lethal mutations

Answer 19

• mutations that are lethal under some conditions
• help researchers study essential genes by controlling gene finction

Question 20

Permissive conditions

Answer 20

mutant allele has wild-type functions

Question 21

Restricitive conditions

Answer 21

mutant allele has defective functions

Question 22

Phenocopy

Answer 22

phenotype arising from an environmental agent that mimics the effect of a mutant gene
* Not heritable
* Can be deleterious or beneficial

Question 23

Discontinuous traits

Answer 23

give clear-cut, “either or” phenotypic differences between alternative alleles

Question 24

Continuous traits

Answer 24

are determined by segregating alleles of
many genes that interact together and with the environment
* Often appear to blend/unblend
* Usually polygenic
* Also called quantitative traits

Question 25

Polygentic genes

Answer 25

controlled by multiple genes

Question 26

Quantitative trais

Answer 26

traits vary over a range that can be measured

Question 27

Ex. of Continous traits in humans

Answer 27

Height and skin

Question 28

Mendelian explanation of continuous varation

Answer 28

genes or alleles result in more phenotypic classes and more similarity alleles are incomplete dominant and have additive effects the greater # of genes/alleles encoded for a phenotype, the more continuous the result will be