MCB 317 Exam 2 Questions with CORRECT
Answers
True or false?
Based on our discussion in lecture, it is possible for two people with blood type O to have a
child that has blood type B.
True
As discussed in lecture, it is possible for a gene to govern two different traits. Assume there
are two alleles of this gene, which we'll call allele 1 and allele 2. True or false:
If allele 1 is dominant to allele 2 for the first trait, allele 1 must also be dominant to allele 2
for the second trait.
False
In lecture we talked about a situation in which it was not possible to obtain pure-breeding
individuals. Which of the following terms was associated with that situation?
Recessive lethality
True or false?
As discussed in lecture, co-dominance is often due to a dosage effect.
False
As discussed in lecture, epistasis is a gene interaction in which the effects of an allele of one
gene hide (mask) the effects of an allele of another gene. Which gene is the hypostatic gene?
,The gene whose phenotype(s) is masked
Which type of pathway is a signal transduction pathway?
A regulatory switch pathway
True or false?
As discussed in lecture, virtually any biological process can be described in terms of a
pathway.
True
You wish to study a particular process using genetics. You carry out a genetic screen and
isolate several mutants that are defective in the process you are interested in. What
procedure/process do you typically perform to determine how many genes you have
identified in your screen?
Complementation analysis
You have discovered a new type of tropical frog that is indigenous to the United States.
These frogs have three different types of skin coloration, they can be either red, white or
blue depending on which pigment is produced in their skin cells. Each of the three
pigments are produced as part of a single biochemical pathway with the white pigment
being a precursor compound, the red pigment an intermediate and the blue pigment the
final product. A single gene X codes for the enzyme that converts the white pigment into
the red pigment. Similarly a single gene Y encodes the enzyme that converts the red
pigment to the blue pigment. In your frog population you have two alleles of each gene, the
, X and Y alleles are wild-type alleles that produce functional enzymes; whereas the x and y
alleles are null alleles. You cross two frogs that are XxYy heterozygotes. What proportion
of offspring do you expect to see?
9 Blue : 3 Red : 4 White
How many different genotypes can give rise to the unspotted phenotype?
1
How many different genotypes can give rise to the one-spotted phenotype?
2
How many different genotypes can give rise to the two-spotted phenotype?
2
How many different genotypes can give rise to the three-spotted phenotype?
1
How many different genotypes can give rise to the crescent phenotype?
4
As discussed in lecture, which of the following processes can be described by a pathway?
- The catabolic reactions leading to the breakdown of phenylalanine
- Signal transduction
- The biosynthetic reactions leading to the production of adenine
- Krebs cycle
Answers
True or false?
Based on our discussion in lecture, it is possible for two people with blood type O to have a
child that has blood type B.
True
As discussed in lecture, it is possible for a gene to govern two different traits. Assume there
are two alleles of this gene, which we'll call allele 1 and allele 2. True or false:
If allele 1 is dominant to allele 2 for the first trait, allele 1 must also be dominant to allele 2
for the second trait.
False
In lecture we talked about a situation in which it was not possible to obtain pure-breeding
individuals. Which of the following terms was associated with that situation?
Recessive lethality
True or false?
As discussed in lecture, co-dominance is often due to a dosage effect.
False
As discussed in lecture, epistasis is a gene interaction in which the effects of an allele of one
gene hide (mask) the effects of an allele of another gene. Which gene is the hypostatic gene?
,The gene whose phenotype(s) is masked
Which type of pathway is a signal transduction pathway?
A regulatory switch pathway
True or false?
As discussed in lecture, virtually any biological process can be described in terms of a
pathway.
True
You wish to study a particular process using genetics. You carry out a genetic screen and
isolate several mutants that are defective in the process you are interested in. What
procedure/process do you typically perform to determine how many genes you have
identified in your screen?
Complementation analysis
You have discovered a new type of tropical frog that is indigenous to the United States.
These frogs have three different types of skin coloration, they can be either red, white or
blue depending on which pigment is produced in their skin cells. Each of the three
pigments are produced as part of a single biochemical pathway with the white pigment
being a precursor compound, the red pigment an intermediate and the blue pigment the
final product. A single gene X codes for the enzyme that converts the white pigment into
the red pigment. Similarly a single gene Y encodes the enzyme that converts the red
pigment to the blue pigment. In your frog population you have two alleles of each gene, the
, X and Y alleles are wild-type alleles that produce functional enzymes; whereas the x and y
alleles are null alleles. You cross two frogs that are XxYy heterozygotes. What proportion
of offspring do you expect to see?
9 Blue : 3 Red : 4 White
How many different genotypes can give rise to the unspotted phenotype?
1
How many different genotypes can give rise to the one-spotted phenotype?
2
How many different genotypes can give rise to the two-spotted phenotype?
2
How many different genotypes can give rise to the three-spotted phenotype?
1
How many different genotypes can give rise to the crescent phenotype?
4
As discussed in lecture, which of the following processes can be described by a pathway?
- The catabolic reactions leading to the breakdown of phenylalanine
- Signal transduction
- The biosynthetic reactions leading to the production of adenine
- Krebs cycle
