extensions of mendelian inheritance pt.2

Question 1

A heterozygotes possess a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is an example of?

Answer 1

incomplete dominance

Question 2

in four-o’clock plants, red flower color is dominant to white flower color. However, heterozygous plants have pink flowers. If a pink- flowered plant in crossed with a white flowered plant, what will be the phenotypic ratios of their offspring?

Answer 2

1/2 pink, 1/2 white

Question 3

in human blood groups, the fact that an individual can have an AB blood type is an example of

Answer 3

codominance

Question 4

An individual with type A blood and an individual with type B blood mate and have offspring. What is the only blood type can you be certain is possible in their offspring?

Answer 4

type AB blood

Question 5

epistasis is

Answer 5

when one gene can mask the expression of a second gene

Question 6

sickle cell anemia in humans is an example of

Answer 6

overdominance/ heterozygote advantage

Question 7

which term refers to the situation where the effects of one gene mask the phenotype effects of another gene

Answer 7

epistasis

Question 8

the multiple effects of a single gene on the phenotype of an original is called

Answer 8

pleiotropy

Question 9

polymorphism

Answer 9

in large populations there may be more than one common allele

Question 10

why are mutants recessive?

Answer 10

1. 50% of normal levels of protein are enough for full function
2. the one wild-type copy is up-regualted in expression, to produce adequate amount of functional protein

Question 11

dominant alleles

Answer 11

alleles that effect phenotype as just one copy

Question 12

Gain-of-function mutation (dominant allele)

Answer 12

gene gains a new/abnormal function

Question 13

dominant-negative mutations

Answer 13

mutant protein acts to antagonize normal protein

Question 14

haploinsufficiency

Answer 14

mutant is a loss of function allele and one wild type copy is not enough to provide function

Question 15

why are recessive mutant alleles typically produce less functional protein

Answer 15

because the protein is defective or they produce lower levels of the functional protein

Question 16

incomplete penetrance

Answer 16

an allele does not always “penetrate” into the phenotype of the individual

Question 17

penetrance

Answer 17

population of a chromosome carrying the dominant allele and exhibiting the trait

Question 18

what causes incomplete penetrance and variable expressivity

Answer 18

1. the environment may affect the outcome of the trait

2. there may be modifier genes that affect the phenotype

Question 19

norm of reaction

Answer 19

range of phenotypes seen across different environmental effects

Question 20

overdominance / heterozygote advantage

Answer 20

when a heterozygote is more vigorous than the 2 homozygotes

ex: sickle cell anemia

Question 21

explanation for overdominance at the molecular/cellular level

Answer 21

1. disease resistance
2. homodimer formation
3. variation n functional activity

Question 22

heterosis ( hybrid vigor)

Answer 22

out-crossing; cross-pollinating species

Question 23

codominance

Answer 23

both alleles are expressed

ex: blood type

Question 24

sex-influenced traits

Answer 24

an allele is dominant in one sex but recessive in the other

Question 25

sex-limited traits

Answer 25

traits that occur only in one of the two sexes

Question 26

essential genes

Answer 26

genes required for survival

Question 27

lethal allele

Answer 27

an allele with the potential to cause death, usually due to a result in the mutation of an essential gene

Question 28

temperature sensitive conditional lethal allele

Answer 28

temperature sensitive proteins mis-fold at higher temps, becoming nonfunctional

Question 29

conditional lethal allele

Answer 29

an allele that can kill an organism only under certain environmental conditions

Question 30

gene redundancy

Answer 30

existence of multiple genes in the genome of an organism that performs the same function

Question 31

gene dosage

Answer 31

number of copies of a particular gene present in the genome

Question 32

multiple allele system

Answer 32

type of non-mendelian pattern that involves more than typical 2 alleles that code for certain characteristics

Question 33

complementation

Answer 33

relationship between 2 different strains of an organism which both have homozygous recessive mutations that produce same phenotype

Question 34

expressivity

Answer 34

how affected an individual may be to mutation