Deck 4: Gene Interaction

Question 1

Refer to the the table to answer the following questions.

Independent assortment predicts a 9:3:3:1 ratio with four different phenotypes in the F₂ progeny.If the alleles are epistatic,what would you predict?

A)more than four phenotypes
B)fewer than four phenotypes
C)heterozygotes with a novel phenotype between the dominant and recessive homozygotes
D)1/3 of the progeny with the dominant phenotypes and 2/3 recessive
E)no change in the 9:3:3:1 ratio

Answer 1

B

Question 2

Bateson and Punnett crossed two white-flowered lines and saw all purple flowers in the F₁ generation.They concluded this was an example of complementary gene interactions because a cross of the F₁ plants yielded what ratio in the F₂ generation?

A)8 purple to 8 white
B)16 purple to 0 white
C)0 white to 16 purple
D)7 purple to 9 white
E)9 purple to 7 white

Answer 2

E

Question 3

Gene interactions in which an allele of one gene modifies or prevents expression of alleles of another gene is known as

A)complete dominance.
B)incomplete dominance.
C)codominance.
D)epistasis.
E)incomplete penetrance.

Answer 3

D

Question 4

What type of allele is often detected as a distortion in segregation ratios,where one class of expected progeny is missing?

A)dominant negative allele
B)temperature-sensitive allele
C)lethal allele
D)partial dominance
E)incomplete penetrance

Question 5

Most people with the dominant mutant polydactyly allele have extra digits,but at least 25% have the normal number of digits.What is the genetic explanation for this observation?

A)dominant negative allele
B)temperature-sensitive allele
C)lethal allele
D)partial dominance
E)incomplete penetrance

Question 6

If a dominant allele of one gene completely suppresses the phenotypic expression of alleles of another gene,this is an example of

A)recessive interaction.
B)dominant interaction.
C)recessive epistasis.
D)dominant epistasis.
E)dominant suppression.

Question 7

A mutation results in a gene product with a novel function that is not normally found in wild-type organisms.This type of mutation is known as

A)amorphic.
B)hypomorphic.
C)hypermorphic.
D)neomorphic.
E)dominant negative.

Question 8

Which mode of inheritance results in both alleles being detected equally in the heterozygous phenotype?

A)complete dominance
B)incomplete dominance
C)codominance
D)epistasis
E)incomplete penetrance

Question 9

Which mode of inheritance results in the phenotype of a heterozygote being indistinguishable from that of an organism homozygous for the dominant allele?

A)complete dominance
B)incomplete dominance
C)codominance
D)epistasis
E)incomplete penetrance

Question 10

Many oncogenes result from mutations that cause a protein to be expressed in cells where it is normally not expressed or at inappropriate times during development.This type of mutation can be described as

A)amorphic.
B)hypomorphic.
C)hypermorphic.
D)neomorphic.
E)dominant negative.

Question 11

Refer to the the table to answer the following questions.

Which step is catalyzed by the enzyme responsible for the Met 3 mutant?

A)homoserine → cysteine
B)cysteine → cystathionine
C)cystathionine → homocysteine
D)homocysteine → methionine
E)methionine → homoserine

Question 12

Refer to the the table to answer the following questions.

Two pure-breeding mutant plants produce white flowers.When they are crossed,all of the progeny have wild-type purple flowers.What does this genetic complementation tell you?

A)The genes are part of distinct biosynthetic pathways.
B)The two lines exhibit different mutations in the same gene.
C)More than one gene is involved in determining the phenotype.
D)The allele is pleiotropic.
E)The allele exhibits incomplete dominance.

Question 13

Two proteins interact to form a multimeric complex.When one of the proteins is mutated,there is a substantial loss of functional activity in the multimeric protein.This type of mutation is classified as

A)amorphic.
B)hypomorphic.
C)hypermorphic.
D)neomorphic.
E)dominant negative.

Question 14

Most combinations of different ABO alleles result in complete dominance of one allele.Which combination results in codominance?

A)Iᴬᶦ
B)Iᴬᴵᴮ
C)Iᴮᶦ
D)ii
E)either Iᴬᶦ or Iᴮᶦ

Question 15

A mutation resulting in an inactive gene product is classified as

A)amorphic.
B)hypomorphic.
C)hypermorphic.
D)neomorphic.
E)dominant negative.

Question 16

A mutation results in an enzyme that is partially active compared to the wild-type allele.This type of "leaky" mutation is classified as

A)amorphic.
B)hypomorphic.
C)hypermorphic.
D)neomorphic.
E)dominant negative.

Question 17

The 9:6:1 ratio seen in the dihybrid cross of summer squash indicates what genetic relationship between the two genes controlling fruit shape?

A)recessive interaction
B)dominant interaction
C)recessive epistasis
D)dominant epistasis
E)dominant suppression

Question 18

Which mode of inheritance produces heterozygotes with phenotypes that differ from either homozygote but more closely resembles one homozygous phenotype than the other?

A)complete dominance
B)incomplete dominance
C)codominance
D)epistasis
E)incomplete penetrance

Question 19

What is the genotype for individuals with blood type O?

A)Iᴬᶦ
B)Iᴬᴵᴮ
C)Iᴮᶦ
D)ii
E)either Iᴬᶦ or Iᴮᶦ

Question 20

Refer to the the table to answer the following questions.

In the biosynthetic pathway for conversion from homoserine to methionine,you identify a Neurospora crassa double mutant Met1/Met2.This mutant will grow only if which supplement(s)are added to the minimal media?

A)homoserine only
B)cysteine only
C)homocysteine only
D)cystathionine and homocysteine
E)methionine only

Question 21

King George III of England and other members of the royal family were afflicted with a series of strange,seemingly unrelated symptoms including abdominal pain,rapid pulse,convulsions,and insanity.It has been determined that he likely suffered from porphyria,caused by a mutation in a single allele.What is the genetic term describing the alteration of multiple,distinct traits of an organism by a mutation in a single gene?

Question 22

Which antigen,expressed on the surface of all red blood cells,is modified by A- or B-transferases?

Question 23

You cross a white flower with a red flower,and the offspring are all pink.This is an example of what type of inheritance?

Question 24

What are the two categories of gain-of-function mutations?

Question 25

Which type of pathway is responsible for melanin productionthe biosynthetic pathway,signal transduction pathway,or developmental pathway?

Question 26

To better understand which genes are involved in developmental pathways,geneticists use experimental analyses of mutant phenotypes.What is this analytic approach called?

Question 27

A metabolic reaction requires 10 units of enzymatic activity to proceed.If a dominant allele "D" can generate 8 units of enzyme and a recessive allele "d" can generate 2 units of enzyme,what can be said of the dominant wild-type allele?

Question 28

Mendel studied tall and short pure-breeding lines of pea plants.Inherited genetic variation would dictate that one line would produce tall plants and the other short plants,but the genes and phenotypes are influenced by what external factor?

Question 29

A metabolic reaction requires 40 units of enzymatic activity to proceed.If a dominant allele "D" can generate 40 units of enzyme and a mutant allele "d" generates 20 units of enzyme,what can be said of the dominant wild-type allele?

Question 30

An individual is a "universal acceptor," meaning he or she will not have an adverse reaction to a transfusion with any type of blood,has which blood type?

Question 31

The allele responsible for the Siamese coat-color pattern produces an unstable tyrosinase enzyme.This type of gene product is an example of what type of allele?

Question 32

The four different human blood types are caused by how many alleles?

Question 33

Individuals with blood type AB have which blood antibody(ies)?

Question 34

You cross a white flower with a red flower,and the offspring are white with red spots.This is an example of what type of inheritance?

Question 35

The Sbe1 gene controlling pea shape is an example of codominance at the molecular level;the inheritance pattern is seen by detection of how many DNA or RNA bands in heterozygous plants?

Question 36

What are the three categories of loss-of-function mutations?

Question 37

Individuals with blood type A have which blood antigen(s)?

Question 38

Numerous genes contribute to the wild-type red eye color in Drosophila.Two genes,brown and vermilion,produce eye pigments.What does the white gene do?

Question 39

Are loss-of function mutations more likely to be dominant or recessive?

Question 40

In familial hypercholesterolemia,individuals who are homozygous for the mutation lack LDL cholesterol receptors in the liver,causing high levels of serum cholesterol.This is a defect in which type of gene pathwaythe biosynthetic,signal transduction,or developmental pathway?

Question 41

If an organism with a particular genotype fails to produce the corresponding phenotype,the organism is said to be ________ for the trait.

Question 42

________ mutations cause overexpression or result in new functions.

Question 43

Describe the difference between incomplete penetrance and variable expressivity.It is often difficult to pinpoint the cause of incomplete penetrance or variable expressivity.What possible interactions may be responsible?

Question 44

Explain how the cʰ (Himalayan)allele and tyrosinase control the Siamese coat-color pattern.What is the underlying reason that certain parts of a Siamese cat (e.g.,tail and ears)are darker than the cat's trunk?

Question 45

________ mutations decrease or eliminate gene activity.

Question 46

In Labrador retrievers,coat color is controlled by gene interaction in which homozygosity for a recessive allele can mask the phenotypic expression of a second gene.This genetic interaction is known as ________ and has a characteristic ________ ratio.

Question 47

Proper cross-matching of blood type is essential for safe blood transfusion.What is the general rule for safe blood transfusion,and what are the consequences if a patient receives the incorrect blood type by accident? If a patient's blood type is unknown,what is the safest course of action?

Question 48

Iᴬ and Iᴮ alleles exhibit ________ over the i allele.

Question 49

You have crossed two Mexican hairless dogs,and the offspring are 1/3 hairy and 2/3 hairless.Given this phenotypic ratio,draw the Punnett square for this cross.What are the genotypes of the P₁ and F₁ dogs in this cross? List the predicted genotype as well as the phenotype for each of the offspring.Which genotypes are hairless,and which are hairy? Can you design a genetic cross that would yield a true-breeding hairless line (where all offspring are hairless)?

Question 50

Phenylketonuria (PKU)is caused by the absence of the enzyme phenylalanine hydroxylase,which catalyzes the first step of the pathway that breaks down the amino acid phenylalanine,a common component of dietary protein.Explain how environmental intervention is commonly practiced to prevent the development of this human autosomal recessive condition.