Question 1

In comparing DNA sequences from two different eukaryotic organisms,which do you expect to vary the most?
A)sequences that code for exons
B)sequences that code for introns
C)sequences that code for a polypeptide
D)sequences that regulate transcription
E)sequences that code for micro-RNAs

Accepted Answer

Introns are non-coding regions that are spliced out during mRNA processing and tend to accumulate more mutations over time, leading to greater variation between different organisms.

Question 2

Even though bacteria are more simple than eukaryotes,genomic data on bacteria was surprising because _____.
A)very few species contain plasmids
B)there is only one copy of each gene present within a bacterial genome
C)there are many genes of unknown function
D)bacterial genomes are always contained on a single circular chromosome
E)there is almost no difference between the genomes of diverse bacteria

Accepted Answer

Genomic data on bacteria revealed that there are many genes of unknown function, which was surprising considering their relative simplicity compared to eukaryotes.

Question 3

The mechanism for the spread of LINES involves some unusual features,including _____.
A)translation in the cytoplasm of an mRNA that was synthesized in the nucleus
B)the nuclear localization of RNA polymerase
C)the transport of mRNA from the cytoplasm to the nucleus
D)the use of an enzyme that cuts DNA
E)the use of RNA polymerase to transcribe an mRNA

Accepted Answer

C

Question 4

The bulk of the sequence data in whole genome sequencing comes from _____.
A)relatively large (~ 160 kb)sequences cloned into BACs
B)relatively small (~ 1000 base-pair)sequences cloned into plasmids
C)whole chromosomes obtained without cloning
D)whole chromosomes cloned into plasmids

Accepted Answer

Whole genome sequencing typically involves breaking the genome into smaller fragments, which are then cloned into plasmids for sequencing. These fragments are usually around 1000 base pairs in length.

Question 5

Sequencing eukaryotic genomes is more difficult than sequencing genomes of bacteria or archaea because of _____.
A)the large size of eukaryotic proteins
B)the hard to find proteins
C)the high proportion of G-C base pairs in eukaryotic DNA
D)the large size of eukaryotic genomes and the large amount of eukaryotic repetitive DNA
E)the large size of eukaryotic genomes,the large amount of eukaryotic repetitive DNA,and the high proportion of G-C base pairs in eukaryotic DNA

Accepted Answer

Eukaryotic genomes are generally very large and contain a significant amount of repetitive DNA, which can make it difficult to accurately sequence and assemble the genome. Bacteria and archaea have much smaller genomes, with less repetitive sequences, making them easier to sequence. G-C base pairs can also affect sequencing accuracy, but this is not the primary reason for the difficulty in sequencing eukaryotic genomes.

Question 6

Although transposable elements and simple tandem repeats (STRs)are both repetitive DNAs,they differ in that _____.
A)STRs occur within exons;transposable elements occur within introns
B)STRs occur within introns;transposable elements occur within exons
C)the repeated unit in STRs is clustered one after another;transposable element repeats are scattered throughout the genome
D)the repeated unit in STRs is much larger than the repeated unit of transposable elements
E)variation in STR repeat number comes from STR movement in the genome;variation in transposable element repeat number comes from errors in DNA replication

Accepted Answer

Simple tandem repeats consist of a cluster of repeated units that are adjacent to each other, while transposable elements are scattered throughout the genome.

Question 7

Imagine that your goal is to isolate mouse mutants that stabilize microsatellite repeat sequences (i.e. ,lower the frequency at which their repeat number changes).Which of the following mutations would you predict to have this stabilizing effect?
A)a mutation that reduces the rate of transcription
B)a mutation that reduces the rate of translation
C)a mutation that increases the rate of DNA synthesis
D)a mutation that reduces the occurrence of homologous recombination
E)a mutation that inactivates reverse transcriptase and/or integrase

Accepted Answer

Homologous recombination is a major mechanism for the instability of microsatellite repeat sequences. A mutation that reduces the occurrence of homologous recombination in mice would lower the frequency at which their repeat number changes and stabilize the microsatellite DNA.

Question 8

After finding a new medicinal plant,a pharmaceutical company decides to determine if the plant has any genes that are the same or similar to those of other known medicinal plants.To do this,the company annotates the genome which will _____.
A)determine what protein could be synthesized in a medicine
B)determine what mRNA transcripts are available
C)identify genes and their positions within the genome
D)learn how gene products interact to produce phenotypes

Accepted Answer

Annotating the genome involves identifying genes and their positions within the genome, which allows for comparisons to other known medicinal plants. This does not necessarily determine what protein could be synthesized or what mRNA transcripts are available, nor does it provide information on how gene products interact to produce phenotypes.

Question 9

An early step in shotgun sequencing is to _____.
A)break genomic DNA at random sites
B)map the position of cloned DNA fragments
C)randomly select DNA primers and hybridize these to random positions of chromosomes in preparation for sequencing

Accepted Answer

Shotgun sequencing involves breaking genomic DNA into small fragments at random sites, so choice A is the correct answer. Choices B and C are not early steps in this process.

Question 10

In what sense are studies by 19th-century naturalists and those by early 21st-century genomic biologists similar?
A)Both focus narrowly on the underlying mechanisms of biology.
B)Both use evolutionary theory to guide their work.
C)Both take a reductionist approach by studying only one small part of a complex system.
D)Both focus on observing and describing what exists in their realms of investigation.
E)Both constantly strive to create theoretical frameworks in which to understand their findings.

Accepted Answer

Both focus on observing and describing what exists in their realms of investigation.

Question 11

In establishing paternity by DNA fingerprinting,what proportion of microsatellite repeat alleles in a child come from the father?
A)only ones on the X chromosome
B)1/4
C)1/2
D)3/4

Accepted Answer

Each human has two copies of each autosomal chromosome, one from the mother and one from the father. Therefore, half of the child's microsatellite repeat alleles come from the father. The alleles on the X chromosome also come from the father, but since the question specifies "repeat alleles," which are found on autosomal chromosomes, A is incorrect. B and D are also incorrect as they represent fractions that do not accurately reflect the genetic contribution of the father to the child's microsatellite repeats.

Question 12

Which of the following makes it difficult to identify eukaryotic genes?
A)the proteins are larger in eukaryotes than prokaryotes
B)the coding portions of genes are longer in eukaryotes than prokaryotes
C)the lack of analogy between eukaryotic genes
D)the presence of many introns

Accepted Answer

The presence of many introns in eukaryotic genes makes it difficult to identify the coding portion of the gene, as the introns need to be removed before the mRNA can be translated into protein.

Question 13

Why are transposable elements considered to be selfish genes?
A)They have multiple promoters.
B)They require multiple RNA polymerases for transcription.
C)They replicate using the host's resources without direct benefit to the host.
D)They do not produce mRNA.

Accepted Answer

Transposable elements are considered to be selfish genes because they replicate using the host's resources without providing any direct benefit to the host. They may even have negative impacts on the host genome by causing mutations or disrupting important genes. Choices A, B, and D are incorrect because they are not necessarily characteristics of transposable elements that make them selfish genes.

Question 14

If the sequence of a cDNA matches a DNA sequence in the genome,then this genomic DNA is likely to _____.
A)code for a protein
B)code for a ribozyme
C)code for an rRNA
D)be part of an intron
E)be a regulatory sequence

Accepted Answer

cDNA is complementary DNA that is made from mRNA by reverse transcription. Therefore, if the sequence of a cDNA matches a DNA sequence in the genome, it means that the particular genomic DNA codes for a messenger RNA (mRNA), which in turn codes for a protein.

Question 15

Biologists now routinely test for homology among potentially related species using DNA sequences.These tests reveal if the sequences from each species _____.
A)are related by descent from a common ancestor
B)are related because of convergent evolution
C)are related by chance mutations
D)code for identical proteins
E)code for identical RNAs

Accepted Answer

Testing for homology among DNA sequences can reveal if the sequences are related by descent from a common ancestor. This is because species that are closely related evolutionarily are expected to share more similarities in their DNA sequences compared to species that are more distantly related. Convergent evolution, chance mutations, identical proteins, and identical RNAs do not necessarily imply evolutionary relatedness.

Question 16

A scientist needs to find a collaborating scientist to help her with organizing a large amount of sequence data from the genome of a previously unsequenced and rare plant.This scientist should find a collaborator who specializes in _____,
A)proteomics
B)functional genomics
C)evolutionary genomics
D)bioinformatics

Accepted Answer

A bioinformatics specialist would have the necessary expertise to handle large amounts of sequence data and organize it into meaningful information. They would also be familiar with the necessary software and tools to analyze the data and derive insights from it. Proteomics would not be relevant to sequence data, while functional genomics and evolutionary genomics may be useful in analyzing the data but would not necessarily be the primary focus of organizing the data.

Question 17

Imagine that you've sequenced the genome of a human pathogenic bacterium.In the early stages of analysis,you discover a stretch of DNA that has a significantly different GC content (the proportion of bases that are G and
A)convergent evolution
B)both sequences are introns
C)a high rate of mutation
D)a low rate of mutation
E)lateral gene transfer

Accepted Answer

A significantly different GC content in a stretch of DNA in a human pathogenic bacterium suggests lateral gene transfer, which is the horizontal transfer of genetic material from one organism to another. This transfer can result in the acquisition of novel traits or functions, such as antibiotic resistance genes, that could contribute to the pathogenicity of the bacterium.

Question 18

When comparing the genomes of a bacterial parasite versus a free-living,nonparasitic bacterium,one expects to find _____.
A)the proportion of G-C base pairs will be significantly higher in the parasite
B)no homology between the free-living and parasitic bacteria
C)there will be a higher proportion of genes of unknown function in the parasite
D)the parasite will have acquired a smaller proportion of its genes through lateral gene transfer
E)the parasite will have a smaller genome

Accepted Answer

The answer of When comparing the genomes of a bacterial...

Question 19

LINES transposable elements are closely related to _____.
A)plasmids
B)retroviruses
C)poliovirus
D)restriction enzymes
E)DNA polymerase

Accepted Answer

LINES transposable elements are similar to retroviruses in structure and mechanism of transposition. Both have reverse transcriptase enzymes, which allow for the retrotransposition of RNA into DNA and insertion into new sites in the genome. Plasmids, poliovirus, restriction enzymes, and DNA polymerase are not closely related to LINES transposable elements.

Question 20

Forensic DNA fingerprinting often involves recovery of minute quantities of DNA from a crime scene.What is a concern in analyzing this DNA?
A)There is seldom enough DNA to allow PCR amplification.
B)Even with these tiny amounts of DNA,there may be too much DNA for efficient PCR.
C)Restriction enzymes may not work efficiently on the PCR-amplified DNA.
D)It is critical to avoid the introduction of contaminating human DNA unrelated to the crime.

Accepted Answer

It is critical to avoid contamination of the DNA sample with unrelated human DNA, as this could lead to false results and incorrect conclusions. Careful sample collection and handling, as well as using proper laboratory procedures, can minimize the risk of contamination. The other options (A, B, and C) are not generally concerns in analyzing DNA from a crime scene, as there are sophisticated techniques available to amplify and analyze even very small amounts of DNA.

Quiz 20: Genomics

In comparing DNA sequences from two different eukaryotic organisms,which do you expect to vary the most?

Even though bacteria are more simple than eukaryotes,genomic data on bacteria was surprising because _____.

The mechanism for the spread of LINES involves some unusual features,including _____.

The bulk of the sequence data in whole genome sequencing comes from _____.

Sequencing eukaryotic genomes is more difficult than sequencing genomes of bacteria or archaea because of _____.

Although transposable elements and simple tandem repeats (STRs) are both repetitive DNAs,they differ in that _____.

Imagine that your goal is to isolate mouse mutants that stabilize microsatellite repeat sequences (i.e. ,lower the frequency at which their repeat number changes) .Which of the following mutations would you predict to have this stabilizing effect?

After finding a new medicinal plant,a pharmaceutical company decides to determine if the plant has any genes that are the same or similar to those of other known medicinal plants.To do this,the company annotates the genome which will _____.

An early step in shotgun sequencing is to _____.

In what sense are studies by 19th-century naturalists and those by early 21st-century genomic biologists similar?

In establishing paternity by DNA fingerprinting,what proportion of microsatellite repeat alleles in a child come from the father?

Which of the following makes it difficult to identify eukaryotic genes?

Why are transposable elements considered to be selfish genes?

If the sequence of a cDNA matches a DNA sequence in the genome,then this genomic DNA is likely to _____.

Biologists now routinely test for homology among potentially related species using DNA sequences.These tests reveal if the sequences from each species _____.

A scientist needs to find a collaborating scientist to help her with organizing a large amount of sequence data from the genome of a previously unsequenced and rare plant.This scientist should find a collaborator who specializes in _____,

Imagine that you've sequenced the genome of a human pathogenic bacterium.In the early stages of analysis,you discover a stretch of DNA that has a significantly different GC content (the proportion of bases that are G and

When comparing the genomes of a bacterial parasite versus a free-living,nonparasitic bacterium,one expects to find _____.

LINES transposable elements are closely related to _____.

Forensic DNA fingerprinting often involves recovery of minute quantities of DNA from a crime scene.What is a concern in analyzing this DNA?