exam 3

Question 1

An adipocyte is a type of fat storage cell that, once fully differentiated, no longer divides. Fully differentiated fat cells are in which phase of the cell cycle?
a. M phase
b. G2 phase
C. G1 phase
d.S phase
e.G0 phase

Answer 1

e.G0 phase

Question 2

After chromosomes condense, the
___________ is the region where the identical DNA molecules are most tightly attached to each other?
a. Kinetochore
b. Aster
c. Centrosome
d. Centriole
e. Centromere

Answer 2

e. Centromere

Question 3

The diploid number of chromosomes in the mustard plant, Arabidopsis thaliana, is 10. Knowing this, how many Chromatids will be present in a plant pollen cell at the end of metaphase I of meiosis?
a. 40
b. 20
c. 10
d. I have no idea Dr. Trott…
e. 5

Answer 3

b. 20

Question 4

Which of the following is NOT true about Cohesin?
a. Is a 6-subunit hexameric protein complex
b. Coats sister chromatids along their entire length
c. holds sister chromatids together
d. Has its highest concentration at centromeres

Answer 4

a. Is a 6-subunit hexameric protein complex

Question 5

Which cell cycle checkpoint can be passed only if the cell size is large enough, nutrient availability is sufficient, and growth factors are present?
a. Zygotene checkpoint
b. S-phase checkpoint
c. G1/S checkpoint
d. G2/M Checkpoint
e. Metaphase checkpoint

Answer 5

c. G1/S checkpoint

Question 6

Prior to meiosis, an Pre-Oocyte cell has the genotype AaBBCcDd. What is the predicted frequency of a fully formed gamete (egg) with the genotype aBCd from this cell?
a. 3/16
b. 1/16
c. 1/2
d. 1/8
e. 1/4

Answer 6

d. 1/8

Question 7

In a dihybrid cross between two heterozygotes, you expect to observe a 9:3:3:1 ratio. However, after performing this type of cross you instead observe a 9:6:1 ratio in the offspring. Which type of epistasis has occurred between these two genes?
a. Dominant suppression
b. Dominant epistasis
c. Recessive epistasis
d. Dominant gene Interaction
e. Complementary gene

Answer 7

d. Dominant gene Interaction

Question 8

During which phase of prophase I does crossing over between non-sister chromatids begin?
a. Leptotene
b. Zygotene
c. Pachytene
d. Diplotene
e. diakinesis

Answer 8

c. Pachytene

Question 9

Which of the following is correct regarding individuals who are blood type B?
a. They express A-transferase that adds N-acetylgalactosamine to the H antigen.
b. They carry both the anti-A and anti-B antibodies.
c. Their blood cells would clump when they receive blood from an individual with the genotype IBi
d. They express B-transferase that adds galactose to the H antigen.
e. Their cells carry the A and B antigens

Answer 9

They express B-transferase that adds galactose to the H antigen.

Question 10

In humans, individuals with green eyes often carry mutations of the genes OCA2 and HERC2 on Chromosome 15. Mutations in these genes cause a reduction of melanin production below that of the “normal” brown eyes, but above that of those with blue eyes where essentially no brown pigment is made. How would you classify this green eye mutation that produces very low, but non-zero, levels of the melanin in eyes when homozygous? (2 points)
a. Hypomorphic mutation
b. Hypermorphic mutation
C. Dominant negative mutation
d. Neomorphic mutation
e. Null mutations

Answer 10

a. Hypomorphic mutation

Question 11

In 1936, researchers Walter Landauer and Elizabeth Upham observed that chickens that expressed the dominant frizzle gene produced feathers that curled outward rather than lying flat against their bodies. However, this was not the only phenotypic effect of this gene — along with producing defective feathers, the frizzle gene caused the fowl to have abnormal body temperatures, higher metabolic and blood flow rates, and greater digestive capacity. Furthermore, chickens who had this allele also laid fewer eggs than their wild-type counterparts. Which term below best describes this genetic situation?
a. Epistasis
b. Codominance
c. Pleiotropy
d. Expressivity
e. penetrance

Answer 11

c. Pleiotropy

Question 12

The example presented above is best described as an example of which of the following? Assume the individuals in the first line are both true breeding. (pic of black mom & white dad and gray child kitty)
a. Incomplete dominance
b. Dominant epistasis
c. Variable penetrance
d. Co-dominant alleles
e. Basian probability

Answer 12

a. Incomplete dominance

Question 13

The example presented above is best described as an example of which of the following? Assume the individuals in the first line are both true breeding. (pic of white horse, black horse and baby spotted horse)
a. Incomplete dominance
b. Dominant epistasis
c. Variable penetrance
d. Co-dominant alleles
e. Basian probability

Answer 13

d. Co-dominant alleles

Question 14

Cationic trypsinogen is an enzyme made in the pancreas that helps to digest food. It is encoded for by the PRSS1 gene. Individuals with a disorder called hereditary pancreatitis have mutations in the PRSS1 gene, which result in inflammation of the pancreas, possibly leading to permanent tissue damage. The disorder is inherited in an autosomal dominant fashion. Studies of large human populations have determined that the penetrance of a particular PRSS1 mutation, Arg 122His, is 64%

Imagine that you are part of a research team interested in determining the penetrance of a different PRSS1 mutation, Ala16Val. Your team has identified 350 individuals with the PRSS1 Ala 16Val allele and found that 80 of the individuals showed clear evidence of pancreatitis. From your data, what is the penetrance of the PRSS1 Ala16Val mutation, state your answer in percentage?

a. 64%
b. 33.5%
C. 23%
d. 77%
e.100%

Answer 14

C. 23%

Question 15

Which step is catalyzed by the enzyme responsible for the Met 3 mutant?
see number 14
homocysteine → methionine
b. methionine → homoserine
c. cystationine → homocysteine
d. cysteine → cystathionine
e. homoserine → cysteine

Answer 15

d. cysteine → cystathionine

Question 16

Given that: C > Cch > Ch > c.
Clearly show the expected genotypes, phenotypes and ratios expected from a cross between a wild-type rabbit (Cc) and a Chinchilla rabbit (Cch Ch)

Answer 16

C C^ch → full coat 1/2

C C^h → full coat color

C^ch c → chinchilla - 1/4

c^h c → Himalayan - 1/4
2:1:1

Question 17

What name is used to describe your blood type if you are l^Ai; h/h? (2 points)

Answer 17

Bombay which is recessive for H antigen

Question 18

What name is used to describe your blood type if you are l^Ai; h/h? (2 points)

Question 19

see number 17
about meiosis and mitosis

Answer 19

a- anaphase 1 meiosis
b- metaphase of mitosis
c- telophase of mitosis
d- anaphase of mitosis

Question 21

what is the probability that their next child will have favism?

Answer 21

1/16 (for our test)

Question 22

In mice, agouti fur is a dominant trait resulting in individual hairs having a light band of pigment on
an otherwise dark hair shaft. Solid color fur, is the recessive phenotype (A_ = agouti; aa = solid
color). A separate gene (B or b) can result in either a dominant black pigment or a recessive brown
pigment (B_ = black; bb = brown).

A. If two Agouti Black mice (heterozygous for both genes) are mated. What fraction of the progeny would you expect to be Agouti/Black? (2 points)

Answer 22

9/16

Question 23

In addition to A and a, the “agouti” gene has a third allele, AY. The AY allele is fully dominant to both A and a alleles. The homozygous genotype (AYAY) results in lethality before birth. The heterozygous genotypes (A’A or Ava) result in yellow fur color, regardless of which alleles are present for the B/b gene.
In a mating of mice with the genotypes AYABb X AYaBb (both Yellow), what fraction of the live progeny are expected to have:
B. Yellow fur (2 points)
C. Agouti Brown (cinnamon) (2 points)

Answer 23

b. 2/3

c. 1/12

Question 24

see number 20

You discover a new compound that Saccaromyces cereviciae require for survival. To find genes involved in the synthesis of this compound (Trottmium) you have screened for mutants that cannot grow on minimal media, but can grow on minimal media supplemented with Trottmium. You
perform a complementation test with 10 mutants. The results are shown below (+ = growth, - = no
growth).

a. Place the mutants into complementation groups.

b. How many genes are represented in the data above? (2 points)

Answer 24

a. 1, 3, 9, 10
2, 7
4, 5, 6, 8

b. 3 genes