Deck 10: Genome Evolution

Question 1

From the figure above,one can deduce that larger genomes

A)tend to have a greater proportion of coding DNA than smaller genomes.
B)tend to have a lesser proportion of coding DNA than smaller genomes.
C)have more splice variants.
D)code for more proteins.

Answer 1

B

Question 2

The C-value paradox is

A)the lack of correlation between genome size with organismal complexity.
B)resolved by the identification of noncoding DNA.
C)resolved by the discovery of linkage disequilibrium.
D)A and B
E)All of the above

Answer 2

D

Question 3

From where is DNA acquired during conjugation?

A)The environment
B)Bacteriophage
C)Other bacteria
D)All of the above
E)None of the above

Answer 3

C

Question 4

The nematode,C.elegans,and humans have nearly identical numbers of protein coding genes,yet humans have much more complex organismal features.This is an example of

A)the C-value paradox.
B)the G-value paradox.
C)cell size paradox.
D)linkage disequilibrium.
E)None of the above

Question 5

A bacteriophage was the first organism to have its genome sequenced.Sequencing of this genome was facilitated by

A)its complex genome.
B)its short genome.
C)previous studies of bacterial genomes.
D)A and C
E)All of the above

Question 6

How many inversions can be inferred from the following syntenic dot plot?

A)One
B)Two
C)Three
D)Four
E)Five

Question 7

What does the figure above convey about the G-value paradox in prokaryotes?

A)The numbers of protein coding genes increase with genome size.
B)There is no G-value paradox in prokaryotes.
C)Bacteria are more complex than archaea.
D)A and B
E)None of the above

Question 8

Refer to the figure below to answer the following question.A researcher discovers a new bacteria whose genome is ~8 Mb in size.What type of bacteria is this likely to be?

A)Free-living
B)Obligate parasite
C)Obligate symbiont
D)Any of the above
E)Cannot be determined from the information provided

Question 9

Horizontal gene transfer

A)is also known as lateral gene transfer.
B)occurs via transduction.
C)occurs via transformation.
D)occurs via conjugation.
E)All of the above

Question 10

Prokaryotes may have

A)one single circular chromosome.
B)many circular chromosomes.
C)one single linear chromosome.
D)A and B
E)All of the above

Question 11

Factors that contribute to overall genome size include

A)small genetic elements capable of self-catalyzing their movement.
B)selection on cell size.
C)selection on replication speed.
D)A and B
E)All of the above

Question 12

The G-value paradox states that

A)genome size does not correlate with organismal complexity.
B)the number of protein coding sequences does not correlate with organismal complexity.
C)genome size does not correlate with the number of protein coding sequences.
D)B and C
E)All of the above

Question 13

Transposons

A)move within a genome without making duplicates.
B)move within a genome while making duplicates.
C)use an RNA intermediate.
D)use a DNA intermediate.
E)All of the above

Question 14

Telomeres are necessary because

A)RNA needs a DNA template.
B)Okazaki fragments need a binding region.
C)prokaryotic genomes are circular.
D)DNA polymerase only works in the 5¢ to 3¢ direction.
E)chromosomes would grow during each replication.

Question 15

GC content refers to

A)the G-value paradox.
B)the C-value paradox.
C)the fraction of G and C nucleotides in the genome.
D)A and B
E)All of the above

Question 16

Transposons can be deleterious to a host genome because they can

A)disrupt a protein coding sequence.
B)disrupt regulatory elements.
C)generate mutations.
D)cause recombination errors.
E)All of the above

Question 17

Syntenic dot plots are useful when

A)comparing gene orders in prokaryotes.
B)identifying inversions.
C)examining genomic evolution.
D)A and B
E)All of the above

Question 18

Viral genomes

A)may consist of DNA.
B)may consist of RNA.
C)may be linear.
D)may be circular.
E)All of the above

Question 19

How does mutational bias influence GC content?

A)G is more likely to mutate to A.
B)C is more likely to mutate to T.
C)G is less likely to mutate to C.
D)A is less likely to mutate to T.
E)All of the above

Question 20

Eukaryotic genome size is

A)tightly correlated with organismal complexity.
B)not well correlated with organismal complexity.
C)largest in humans.
D)typically smaller than prokaryotic genome size
E)approximately the same in all eukaryotes.

Question 21

While sequencing a bacterial genome,a researcher notes that G is more common on the leading strand than the lagging strand.This is an example of what phenomenon?

Question 22

In the figure below,a double crossing-over event occurs between the Alu elements.How does this event illustrate a means by which introns generate genetic diversity?

Question 23

In the figure below,what is the range of genome size for protozoa? What does this tell us about the relationship between genome size and organismal complexity?

Question 24

What are transcription factors and how do they address the G-value paradox?

Question 25

When comparing recombination rates between a dog,with a genome size of 2410 Mb,and a mustard weed,with a genome size of 100 Mb,which would you expect to have a larger recombination rate per kilobase? Explain your answer.

Question 26

In a 100 bp stretch of a gene,a researcher counts 25 nonsynonymous substitutions,30 synonymous substitutions,and 65 nonsynonymous sites.What type of selection is operating on this gene sequence? Show your work.

Question 27

Describe a haplotype block.

Question 28

The exon theory of genes states that

A)genes consist solely of exons.
B)introns are deleterious and are purged from the genome.
C)introns lead to recombination errors.
D)many current genes arose through the rearrangement of exons.
E)introns disrupt protein structure.

Question 29

Recombination rates across a chromosome

A)are highly variable.
B)are large in recombination hotspots.
C)are nearly equal.
D)A and B
E)None of the above

Question 30

In the syntenic dot plot of E.coli K-12 strains A and B,there are two circled dots in the lower right corner of the plot.How do you interpret the position of these two dots in terms of the gene orders of the two strains?

Question 31

Under the neutral model,allele frequency distributions are driven by

A)the effective population size.
B)the mutation rate.
C)selection.
D)A and B
E)None of the above

Question 32

Why are transposons considered selfish genetic elements?

Question 33

The McDonald-Kreitman test compares substitution rates

A)between and within species.
B)across two time scales.
C)across genes.
D)A and B
E)All of the above

Question 34

Explain how horizontal gene transfer is different than sexual reproduction.

Question 35

A researcher collects a soil sample and sequences the entire genomes of two prokaryotes found in the sample.In these genomes,he finds identical prophage DNA located in different areas of the two genomes.Based on the similarity of the sequences of the prophages and their placement in the prokaryotes' genomes,what could he conclude about the relatedness of the two prokaryotes?

Question 36

A limitation of examining Ka/Ks ratios is that they

A)are sensitive to demographic changes.
B)cannot be used in introns.
C)can only detect positive selection.
D)cannot detect drift.
E)None of the above

Question 37

When examining the recombination rate across a chromosome,a researcher detects an area of high recombination rates.What could she infer based on this observation?

A)This region is likely the centromere.
B)This region is likely a telomere.
C)This region is likely an isochore.
D)This region is in a protein coding gene.
E)None of the above

Question 38

Consider two species,one of which has an effective population size that is five orders of magnitude greater than the other.In which species would you expect to see a smaller genome size? Explain your reasoning.