Quiz 3- Chapters 9 and 11

Which of the following is a true statement about viral genomes?

 

They contain enough genes to allow viruses to replicate independently (without a host cell).

 

They can be made of DNA or RNA, depending on the type of virus.

 

They are always composed of double-strand nucleic acids.

 

They are larger than most bacterial genomes.

They can be made of DNA or RNA, depending on the type of virus.

A single-nucleotide polymorphisms (SNP) found in the conserved sequence of the regulatory region of a gene is likely to

 

affect protein folding.

 

affect when and where the gene is expressed.

 

be a new mutation.

 

be found in plants as well as humans.

affect when and where the gene is expressed.

Horizontal gene transfer is rare and thus has had little influence on the genomes of bacteria.

 

True

 

False

False

Which of the following DNA sequences is NOT commonly carried on a DNA-only transposon?

 

transposase gene

 

reverse transcriptase gene

 

recognition site for transposase

 

antibiotic-resistance gene

reverse transcriptase gene

Viruses reproduce inside a host cell because

 

viruses package DNA from the host-cell genome into the virus particle.

 

viruses need host-cell reverse transcriptase to convert RNA into DNA.

 

viruses use host-cell ribosomes to produce viral coat proteins.

 

all viruses must insert their genomes into the host-cell genome in order to be replicated.

viruses use host-cell ribosomes to produce viral coat proteins.

Membrane proteins that pump ions in and out of the cell are classified as receptors.

 

True

 

False

False

Scramblases make the two monolayers of a bilayer membrane more similar, whereas flippases make them more different.

 

True

 

False

True

Membrane proteins, like membrane lipids, can move laterally by exchanging positions with other membrane components. Which type of membrane protein is expected to be the least mobile, based on its function?

 

channels

 

anchors

 

receptors

 

enzymes

anchors

Three phospholipids, X, Y, and Z, are distributed in the plasma membrane as indicated in Figure 11-1. The composition of the extracellular (noncytosolic) layer is different from that of the cytosolic layer. Which of the following factors is responsible for establishing this compositional asymmetry?

Figure 11-1

 

scramblase

 

lipase

 

flippase

 

lipoyl transferase

flippase

Which of the following types of lipids is the most abundant in the plasma membrane?

 

phospholipids

 

glycolipids

 

sterols

 

triacylglycerides

phospholipids

Which of the following is true of a retrovirus, but NOT of the Alu retrotransposon?

 

It requires cellular enzymes to make copies.

 

It can be inserted into the genome.

 

It can be excised and moved to a new location in the genome.

 

It encodes its own reverse transcriptase.

It encodes its own reverse transcriptase.

Which of the following situations would facilitate the process of exon shuffling?

 

shorter introns

 

a haploid genome

 

exons that code for more than one protein domain

 

introns that contain regions of similarity to one another

introns that contain regions of similarity to one another

Nearly every instance of DNA duplication leads to a new functional gene.

 

True

 

False

False

Which of the following statements about gene families is FALSE?

 

Because gene duplication can occur when crossover events occur, genes are always duplicated onto homologous chromosomes.

 

Not all duplicated genes will become functional members of gene families.

 

Whole-genome duplication can contribute to the formation of gene families.

 

Duplicated genes can diverge in both their regulatory regions and their coding regions.

Because gene duplication can occur when crossover events occur, genes are always duplicated onto homologous chromosomes.

Where does most new membrane synthesis take place in a eukaryotic cell?

 

in the Golgi apparatus

 

in the endoplasmic reticulum

 

in the plasma membrane

 

on ribosomes

in the endoplasmic reticulum

Which of the following mechanisms best describes the process by which nutrients are taken up selectively at the apical surface and then released from the basal and lateral surfaces of the epithelial cells that line the gut?

 

Proteins are tethered to the cell cortex.

 

Proteins are tethered to the extracellular matrix.

 

Proteins are tethered to the proteins on the surface of another cell.

 

Protein movement is limited by the presence of a diffusion barrier.

Protein movement is limited by the presence of a diffusion barrier.

Consider the apical location of a particular protein expressed in epithelial cells, as illustrated in part A of Figure 11-3 below. Part B shows the redistribution of this protein around the entire cell. Which of the following defects is most likely to have caused this redistribution?

Figure 11-3

 

 

a nonfunctional protein glycosylase

 

the deletion of a junctional protein

 

the truncation of a protein found in the extracellular matrix

 

a nonfunctional flippase

the deletion of a junctional protein