Evo- Chapter 10

In both prokaryotes and eukaryotes, when we look at the protein-coding regions within a genome, we observe the codon usage bias, in which some codons occur more frequently than others yet specify the same amino acid. Which of the following is a possible explanation of this phenomenon?

A codon for which complementary tRNAs are common can be translated more quickly than a codon for which complementary tRNAs are rare.

Which of the following statements is FALSE regarding the figure shown, which depicts the relationship between cell size and genome size among vertebrates? https://services.wwnorton.com/aws/image?u=0&file=/wwnorton.college.public/coursepacks/bio/evolut2/imgs/bergstrom_cp_1002.jpg

Birds have the smallest genomes out of the species shown.

Which of the following is FALSE regarding recombination across genomes, including the human genome?

Genomes are broken up into a series of discrete haplotype blocks with a great genetic diversity and high genetic recombination within them.

Which of the following correctly depicts the order in which whole genomes were first sequenced for the listed taxa?

Haemophilus influenzae, then Saccharomyces cerevisiae, then Caenorhabditis elegans, then Homo sapiens

In eukaryotes, protein-coding genes are typically composed of exon regions that code for protein products, interspersed with intron regions that are spliced out before translation. The exon theory of genes proposes an evolutionary explanation for this feature of eukaryotic genomes. Choose the best summary of this theory.

In the presence of introns, unequal recombination is likely to occur between the exons, creating new combinations of protein domains without disrupting the structure of the individual domains.

Which of the following statements regarding the eukaryotic genome structure is FALSE?

Most eukaryotic genomes code for proteins.

Viral genomes tend to be extremely compact due to the effects of strong selection on genome size. Which of the following explains why such a remarkable degree of compression can be achieved?

Multiple genes may be packed into a single region of the genome

Which of the following statements does NOT resolve the C-value paradox to some extent?

Prokaryotic horizontal gene transfer is essentially "bacterial sex."

Which of the following is TRUE regarding prophage DNA in a prokaryotic genome?

Prophage DNA often encodes virulence factors

What is the role of telomerase (a protein-based enzyme with an RNA template) in eukaryotic DNA replication?

Telomerase extends the 3' end of a chromosome, adding a specific repeat sequence.

What conclusions can be drawn from the syntenic dot plot shown in the following figure? https://services.wwnorton.com/aws/image?u=0&file=/wwnorton.college.public/coursepacks/bio/evolut2/imgs/bergstrom_cp_1003.jpg

The two species shown share almost no similarity in gene order.

Which of the following statements describes the C-value paradox?

There is an enormous variation in genome size across taxa, but organismal complexity does not correlate well with genome size.

Which of the following statements is FALSE regarding syntenic dot plots?

They reveal extremely slow change in prokaryotic genome structure over time.

When a gene is first acquired by horizontal transfer, it will have a GC content and codon usage pattern characteristic of the species from which it was received. However, over time, different evolutionary processes drive GC content and codon usage toward patterns characteristic of the recipient species. Which of the following does NOT facilitate that change over time?

migration

Which of the following was NOT found in the genome of the severe acute respiratory syndrome (SARS) coronavirus, which was responsible for an epidemic in 2002-2003?

multiple circular chromosomes

Which of the following types of prokaryotes are known to have the smallest genomes? https://services.wwnorton.com/aws/image?u=0&file=/wwnorton.college.public/coursepacks/bio/evolut2/imgs/bergstrom_cp_1001.jpg

obligate symbiotic bacteria

Small, circular DNA molecules in bacterial cells, which often code for resistance to one or more antibiotics and have the ability to move by the process of conjugation, are called __________.

plasmids

Long interspersed elements (LINEs) make up about 17% of the human genome. What type of transposable elements are they?

retrotransposons

All of the following may be found in prokaryotic genomes except for __________.

spliceosomal introns

One of the problems in hospitals is that some human pathogens, such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae, have active mechanisms for acquiring DNA from the environment (which is released when other cells die). Such DNA can subsequently be incorporated into the genome by recombination and confer resistance to multiple antibiotics. This process of gene transfer is known as __________.

transformation