The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.

Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.

Fitness is a measure of the reproductive success of a particular genotype. The highest fitness is 1.00.

Which of the following is most likely correct concerning the gene for resistance to warfarin? 

#Question id: 2848

#Unit 2. Cellular Organization

Select the answer that names the three functional elements that are required for replication and stable inheritance of chromosomes

#Question id: 2849

#Unit 2. Cellular Organization

Methylation of lysines 4, 36, or 79 of histone H3 typically is associated……… of the genes, whereas methylation of lysines 9 or 27 of the same histone frequently is associated with …..

#Question id: 2850

#Unit 2. Cellular Organization

CCA-adding enzymes add a specific sequence without a template because

#Question id: 2851

#Unit 2. Cellular Organization

There is a growing body of evidence that acetylation of histone N-termini in specific chromosomal regions contributes to gene control by regulating the binding of histones to DNA and regulation of the folding state of chromatin. The extent of histone acetylation is correlated with the relative resistance of chromatin DNA to digestion by nucleases. Which combination of histone acetylation state and DNAse 1 resistance is characteristic of actively transcribed regions of chromatin?

#Question id: 2852

#Unit 2. Cellular Organization

The chromosomal karyotypes of two species of small deer, the Reeves muntjac and the Indian muntjac, are strikingly different despite the fact that the two genomes contain about the same amount of DNA. However, within a species, there are properties of chromosomes that are the same, i.e. species-specific. Select the answer that contains all of these species-specific properties of chromosomes at metaphase

#Question id: 2853

#Unit 2. Cellular Organization

Not all bacteria need to maintain their DNA in a negatively supercoiled state. Bacteria that prefer to grow at very high temperatures must expend energy. Which of the following observation found to be true?

A. Bacteria don’t need to expend energy to prevent their DNA from unwinding due to thermal denaturation

B. These bacterial organisms have a different topoisomerase called reverse gyrase

C. Reverse gyrase decrease the linking number of relaxed DNA in the presence of ATP