Applications and Specialized Areas of GeneticsJuly 2008

Bacterial Genetics

You mix an E. coli strain that is F+ and met- pro- bio- trp- with an E. coli F- strain that is met- pro+ bio- trp+ and plate the cells.

On which plates will these cells NOT grow?a. Minimalb. Minimal + metc. Minimal + prod. Minimal + bioe. a-d

You have the following data from an Hfr mapping experiment in E. coli

Minutes % colonies with the following genotypes

lac+ gal+ trpl+ hip+• 10 3 0 0 0• 15 20 10 1 0• 20 63 30 15 7• 25 90 65 30 22

This results indicate that a. Lac and hip are tightly linkedb. lac and gal are closer to each other than lac and trpc. Lac and trp are closer to each other than lac and gal

A bacterial strain grows on SC – trp media but not SC-leu media. This strain is:A) a trp auxotrophB) a leu auxotrophC) a trp and leu auxotrophD) a prototroph

Minutes cells allowed to mate

leu+ lac+ gal+

10 70 98 0

20 72 87 2

30 74 100 10

% survival with the following genotypes

Which could be the gene order on the bacterial plasmid?A) leu, lac, galB) leu, gal, lacC) gal, leu, lacD) need more information

phage assembly pathway

Let’s say you want to study the genes involved in the assemblypathway of a phage. You collect 6mutants that can notform plaques on a lawn of bacteria.

Your 6 mutants must:A) each have a mutation in a gene required for phage assemblyB) each have a mutation in a different geneinvolved in phage assemblyC) each have a mutation in a gene that is essentialfor phage functionD) each have mutations in genes that cause mutations in the bacterial chromosome.

phage assembly pathway

Next, you want to determinehow many different genes yourmutants represent, so you performa complementation test.

Which is/are true in your complementation test?A) if the mutations of the parents are in the same gene,plaques will not form.B) If the mutations of the parents are in the same gene,plaques will form.C) if the mutations of the parents are in different genes,plaques will form.D) Both A and C are true.E) Both B and C are true.

Complementation Test Results

1 - + - + + +

2 - + + + -

3 - + + +

4 - + +

5 - +

6 -

1 2 3 4 5 6

How many different genes do your 6 mutants represent?A) 6 C) 4B) 5 D) 3

Next, you look at each mutant under the electron microscope and see:

mutant:1,3 - complete heads and complete tails butnot connected2,6 – complete heads, no tails4 – incomplete heads, no tails5 – complete heads and short tails not connectedwild type – complete head connected to long tails

Assuming phage assembly is a linear pathway, which gene is likely epistatic (furthest upstream) to all the other genes?A) 1B) 2C) 4D) 6

mutant:1,3 - complete heads and complete tails butnot connected2,6 – complete heads, no tails4 – incomplete heads, no tails5 – complete heads and short tails not connectedwild type – complete head connected to long tails

Assuming phage assembly is a linear pathway, which gene product likely connects the phage head with phage tails?A) 1B) 2C) 4D) 6

completephage

I1 I2 I3 I44

mutant:1,3 - complete heads and complete tails butnot connected2,6 – complete heads, no tails4 – incomplete heads, no tails5 – complete heads and short tails not connectedwild type – complete head connected to long tails

You feed intermediate 3 (complete head, short tail) to mutant 2 and perform a plaque assay. You see plaques on your plates. Where must gene 2 act?A) upstream of intermediate 3B) downstream of intermediate 3

completephage

I1 I2 I31, 3

I44

mutant:1,3 - complete heads and complete tails butnot connected2,6 – complete heads, no tails4 – incomplete heads, no tails5 – complete heads and short tails not connectedwild type – complete head connected to long tails

Mutant 5 can produce plaques if fed:A) intermediate 3B) intermediate 4C) intermediate 1 or 2D) none of these

completephage

I1 I2 I31, 3

I44 2, 6

Cotransformation between two genes is more likely if they are:A) close to one another.B) far apart from one another.C) both next to the F factor.D) both oriented in the same direction.

Which of the following would NOT be a useful selectable marker?

A)A gene encoding a protein that degrades the antibiotic ampicillin.

B)A gene encoding a protein that allows the cell to synthesize histidine.

C)A gene encoding a protein that is an essential structural component of the cell.

D)All of these are useful selectable markers. E)None of these are useful selectable markers.

The transformed cells that survive on plates containing ampicillin:A) have the AmpR geneB) contain the cloned geneC) contain the cloning vectorD) A, B, and CE) A and C

Using a plasmid that contains the LacZ gene, in the presence of X-gal transformed colonies that contain the cloned gene would be:

A) BlueB) White

Stem Cells

Gene Therapy

Immune System

When a person gets an HIV test, what is the test measuring?

A. The presence of a viral mRNA genome along with the host DNA

B. If there is a DNA copy of viral genes in the host chromosome

C. The presence of antibodies against the HIV virus

Cancer Genetics

Michelle's mother-in-law took Vinblastine, a chemotherapy drug, during her treatment. Vinblastine works by inhibiting the assembly of microtubules during mitosis. One of the side effects of vinblastine is hair loss. Why would this be a side effect?

a. Hair is composed mostly of microtubules, so vinblastine destroys the elasticity of hair and consequently, it falls outb. Hair cells, like cancer cells, are rapidly dividing, so vinblastine affects mitosis in both cell types c. Hair cells are located on the body surface, so they are more sensitive to chemicals that are found in chemotherapy drugs like Vinblastined. All of the above

You are interested in whether mutations in a specific gene cause a predisposition to lung cancer. What kind of family should you study?

A. A family where many members smoke and get lung cancer at a young age

B. A family where no one smokes, but members of the family get lung cancer at a young age

C. A family where many members smoke and get lung cancer at an advanced age

D. A family where no one smokes, but members of the family get lung cancer at an advanced age

Rb is a tumor suppressor. E2F is a transcriptionfactor normally needed for cell cycle progression.Rb inhibits E2F. Under which condition do youexpect a cell to become cancerous?

A. Rb +/-; E2F +/+B. Rb -/-; E2F +/+C. Rb +/+; E2F +/-D. Rb -/-; E2F -/-

Rb

E2F

Cell cycle

p53 is the most commonly mutated gene in solid tumors.Why might this be?

A. The p53 gene is mutated more frequently than other genes in the genome by environmental mutagens.

B. Mutation occurs randomly throughout the genome but only cells that get mutations in p53 later became cancerous.

C. Tumor cells mutate their own p53 gene so that they can out grow their neighbors.

• Pedigree of a family showing the incidence of breast cancer with a particular BRCA1- allele.

• BRCA1+/BRCA1- females that have this particular allele of BRCA1- have a high chance of developing early onset breast cancer, so you can assume that the disease is fully penetrant in this family.

• BRCA1-/BRCA1- individuals do not exist in this family. • Males can get breast cancer, but mutations in BRCA1 do not generally cause

breast cancer in males.

BRCA1- BRCA1+/BRCA1+

BRCA1+/BRCA1+ BRCA1+

What is the mode of inheritance in this family? A. X-linked B. AutosomalC. Maternal (cytoplasmic) D. Y-linked

• Pedigree of a family showing the incidence of breast cancer with a particular BRCA1- allele.

• BRCA1+/BRCA1- females that have this particular allele of BRCA1- have a high chance of developing early onset breast cancer, so you can assume that the disease is fully penetrant in this family.

• BRCA1-/BRCA1- individuals do not exist in this family. • Males can get breast cancer, but mutations in BRCA1 do not generally cause

breast cancer in males.

What is the mode of inheritance in this family? A. X-linked B. AutosomalC. Maternal (cytoplasmic) D. Y-linked

When a person who has one BRCA1- allele, the normal protein is expressed. When a person has two mutant BRCA1- alleles, the normal protein is no longer expressed.

At the cellular level, the BRCA1- allele behaves as a:

A. dominant alleleB. recessive allele

At the organismal level, does the BRCA1- allele behaves as a: A. dominant alleleB. recessive allele

Developmental Genetics

You are studying Drosophila mulleri and you discover a maternal effect gene you call nanu. nanu mRNA is localized to the anterior end of the embryo and promotes the formation of anterior structures. Mutations in the nanu gene are recessive.

In a cross between two nanu heterozygotes, how many of the embryos will have defects in their anterior structures?

A. 100%

B. 50%

C. 25%

D. 0%

You are studying Drosophila mulleri and you discover a maternal effect gene you call nanu. nanu mRNA is localized to the anterior end of the embryo and promotes the formation of anterior structures. Mutations in the nanu gene are recessive.

In a cross between a nanu/nanu mutant female and a +/+ male, how many of the embryos will have defects in their anterior structures?

A. 100%

B. 50%

C. 25%

D. 0%

Which of these would be an example of a homeotic phenotype?A. Fly wings that are shrunken and useless.B. Flies with brown eyes instead of the normal red.C. An abdominal segment that has legs.D. All of these.