genetics progress test 4

In the presence of glucose, where is the lac repressor bound?

lacO

Which of the following summarizes expression of the lac genes in this partial diploid:

I+ P+ OC Z- Y+/ I- P+ O+ Z+ Y- ?

Permease is made both in the presence of and in the absence of lactose; β-galactosidase is only made when lactose is present.

The following hypothetical genotypes have genes A, B, and C corresponding to lacI, lacO, and lacZ, but not necessarily in that order. Data in the table indicate whether β-galactosidase is produced in the presence and absence of the inducer for each genotype. Use this data to identify the correspondence between A, B, and C and lacI, lacO, and lacZ genes.

Table that indicates whether β-galactosidase is produced in the presence and absence of the inducer for each of the four hypothetical genotypes.

A=lacO, B=lacZ, C=lacI

In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP?

decrease in glucose and increase in cAMP

Typically, acetylation of histone tails leads to

relaxed packaging of the chromatin and increased transcription

Which of the following is true of both enhancers and silencers?

They are DNA elements where transcription factors bind.

A region of chromatin has recently become DNAse I hypersensitive. Which enzyme has been activated to cause this change in chromatin structure?

histone acetylase

Loss of Xist gene due to mutation leads to defects in which epigenetic process?

X-inactivation

During RNAi, what do miRNAs target for destruction?

mRNAs

5'-CTG__________-3' is half of a palindromic restriction site. What is the complete sequence?

5'-CTGCAG-3'

Given the following plasmid, what are the sizes of the fragments you would expect from a NotI/ EcoRI double digest?

Restriction map of three enzymes.

1.5 kb, 3 kb, 5.5 kb

Assume that a plasmid is 4000 base pairs in length and has restriction sites at the following locations: 600, 1000, 2200, and 3800. Give the expected sizes of the restriction fragments following complete digestion.

400 bp, 800 bp, 1200 bp, 1600 bp

A DNA fragment is introduced into the lacZ gene of a plasmid, which also contains an ampicillin resistance gene. What is the appearance of bacteria transformed with this plasmid if they are spread on plates containing ampicillin and Xgal?

white colonies that are resistant to ampicillin

Which of the following is true of the sequences found in DNA libraries from human tissues?

Those in a muscle cDNA library should all be present in a brain genomic library.

Which of the following statements is FALSE regarding gene therapy?

The integration of a transgene into the genome of the target cell by a viral vector is not permanent, and therefore it will require repeated treatments.

Which of the following is not an assumption of the Hardy-Weinberg equilibrium?

there is migration into the population

DNA from 100 unrelated people was digested with the restriction enzyme BamHI, and the resulting fragments were separated and probed with a sequence for a particular gene. Three fragment lengths that hybridized with the probe were observed—namely 4.0, 6.0, and 8.0kb—where each fragment defines a different restriction fragment allele. The accompanying illustration shows the gel patterns observed; the number of individuals with each gel pattern is shown across the top.

gel patterns

What the allele frequency of the 8.0kb allele?

0.25

The incidence of phenylketonuria (PKU), an autosomal recessive genetic disorder, is approximately 1 in 4,500 in Ireland. Assuming Hardy-Weinberg equilibrium, what is the frequency of PKU carriers in Ireland?

2.9%

The incidence of Tay Sachs, an autosomal recessive disorder, is approximately 1 in 3,500 in a certain population. Assuming Hardy-Weinberg equilibrium, what is the probability that Sarah, who is phenotypically normal with no family history, and Tom, who despite having an affected sister is phenotypically normal like his parents, will have a child with Tay Sachs?

0.55%

The most common form of color blindness, known as red-green blindness, is an X-linked recessive trait affecting about 8% of the male population in the United States. What proportion of females would you expect to be carriers?

0.147

During a University of Nevada, Reno blood donation campaign, the frequencies of alleles determining the ABO blood groups were determined to be 0.70 for IO, 0.2 for IA and 0.1 for IB. Assuming random mating, what is the expected frequency of blood type AB?

0.04

You are studying ABO blood groups, and you know that 6.25% of the population has genotype IAIA and 42.25% of the population has Type O blood. What is the expected frequency of blood type B?

14%

A researcher is studying a newly discovered gene that causes increased body weight in domesticated chickens. In a mainland population, the frequency of the A1 allele is 0.2, for this gene with two alleles. If 100 of these mainland chicken are transported on a ship to an isolated island with a population of 200 A1A1 chickens, 400 A1A2 chickens, and 400 A2A2 chickens, what would the frequency of the A1 allele in the admixed population?

0.382

Cheetahs exhibit significant inbreeding and loss of heterozygosity due to overhunting and loss of habitat experienced at some point in their evolutionary history. Which genetic mechanism occurs when a large population is substantially reduced at random, acting independently of natural selection?

bottleneck effect

Use the Chi-Square Table to answer this question.

Chi-Square Table

A population of 1000 Jeffrey Pines from Mt. Rose have been genotyped at a gene involved in resistance to blister rust (a type of fungi that attacks pines).The genotypes are:

R1R1 350

R1R2 400

R2R2 250

What is the chi-square (χ2) value and do you reject your chance hypothesis?

36.8; reject