Exam 2: ch. 4, 5, 6

Which of the following observations supports the statement that cytomegalovirus (CMV) has a remarkably broad tropism?

CMV can infect connective tissue cells and parenchymal cells of virtually any organ.

Which of the following names represents a viral order?

Mononegravirales

Rank the following mutations from the least devastating (left) to the most devastating (right) in terms of their most likely impact on a cell's phenotype.

silent mutation, missense mutation, nonsense mutation

Sickle cell anemia is a genetic disorder that causes red blood cells to take on an abnormal, crescent shape. This inherited disorder is the result of a single base change from A to T. This changes the amino acid glutamic acid to valine at position six of the hemoglobin protein. Based on this information, sickle cell anemia results from a(n) ________ mutation.

substitution mutation

What are the components of a nucleotide?

sugar, phosphate group, nitrogenous base

Which of the following is involved in bringing amino acids to the ribosomes?

tRNA

What part of the nervous system is most affected by fatal familial insomnia?

thalamus

Which of the following might result in a frameshift mutation?

Benzopyrene

What is the function of single-strand binding proteins?

Bind to the DNA strands near the replication fork to keep them separated

Place the following events in the correct order as they occur in the lytic cycle: 1. Assembly 2. Penetration 3. Release 4. Replication 5. Attachment

5, 2, 4, 1, 3

Which enzyme is responsible for breaking down a host bacterium's cell wall so that the virus can leave the cell?

Lysozyme

Which of the following is another term for a virus attaching to the host cell?

adsorption

Which of the following is not needed to carry out excision repair in Escherichia coli?

helicase

Choose the true statement(s) about conjugation.

- Conjugation involves the formation of a pilus for gene transfer. - Conjugation is a form of horizontal gene transfer. - Conjugation allows for antibiotic resistance traits to be passed from one bacterium to another.

Which of the following contributes to DNA replication accuracy?

- DNA replication accuracy is improved thanks to complementary base pairing rules. - The capacity to proofread improves DNA replication accuracy.

Choose the TRUE statements about DNA replication.

- Every replication fork will have both a leading and a lagging strand.

Which of the following is found in a mature eukaryotic mRNA molecule?

- Exons - Start codon

Of the following enzymes, which are correctly matched with their function?

- Ligase, covalently bonds adjacent Okazaki fragments - DNA polymerase III, builds most of the DNA on the leading and lagging strand

Choose the true statement(s) about mutations.

- Mutations can provide an evolutionary benefit. - Mutation leads to genetic and phenotypic variation within a species. - In humans, somatic cell mutations are not passed to offspring.

Choose the true statement(s) about plasmids

- Plasmids tend to exist outside of a cell's chromosome. - Plasmid tend to be circular. - Plasmids often contain genes that confer a survival advantage to a cell.

Choose the true statement(s) regarding quorum sensing.

- Quorum sensing is an example of pre-transcriptional gene regulation. - Quorum sensing is a population-based form of gene expression regulation. - Quorum sensing relies on the production of autoinducers.

Choose the true statement(s) about stop codons.

- Under specific circumstances, stop codons may encode non-standard amino acids. - There are several stop codons in the genetic code.

Which of the following are ways that viruses differ from prokaryotes and eukaryotes?

- Unlike prokaryotes and eukaryotes, viruses are incapable of replicating independently from a host cell. - Unlike prokaryotes and eukaryotes, viruses are classified as acellular particles. - Unlike prokaryotes and eukaryotes, viruses are not considered alive.

Choose the TRUE statements regarding phosphodiester bonds: - phosphodiester bonds are created by linking the 3' hydroxyl group to the 5' phosphate group of an adjacent nucleotide - phosphodiester bonds are what hold the "sugar-phosphate" backbone of DNA together - phosphodiester bonds are only in DNA - phosphodiester bonds hold the "rungs" of a double-stranded DNA "ladder" together

- phosphodiester bonds are created by linking the 3' hydroxyl group to the 5' phosphate group of an adjacent nucleotide - phosphodiester bonds are what hold the "sugar-phosphate" backbone of DNA together

Choose the true statement(s) about nonstandard genetically encoded amino acids.

- stop codons encode nonstandard amino acids - selenocysteine is a nonstandard genetically encoded amino acid - pyrrolysine is a nonstandard genetically encoded amino acid

How are RNA nucleotides different from DNA nucleotides?

-RNA nucleotides use the sugar ribose, while DNA nucleotides do not. -RNA nucleotides do not contain thymine.

Place the following events in the correct order as they occur on the lagging strand: 1. Helix unwinding 2. DNA polymerase III builds DNA 3. DNA polymerase I acts 4. Ligase glues Okazaki fragments together 5. RNA primase builds RNA primers

1, 5, 2, 3, 4

In what year did Stanley Prusiner discover prions?

1982

According to the animation, ribosomes move along the mRNA in which direction?

5' to 3'

The leading strand of DNA is synthesized in which direction?

5' to 3' in the same direction as helix unwinding

If the following RNA molecule is reverse transcribed, what would be the resulting sequence? RNA 5' - GAC UAC GUU GAA - 3'

5'- TTC AAC GTA GTC- 3'

Choose the frameshift mutation that is the riskiest for a prokaryotic cell.

An insertion of one DNA nucleotide in the DNA template strand

Which replicative step(s) do animal viruses and bacteriophages have in common?

Attachment Assembly Penetration

How is bacterial translation different from eukaryotic translation?

Bacteria can begin translation before transcription has terminated.

Chlamydia trachomatis is an obligate intracellular bacterium that causes the sexually transmitted disease chlamydia. When this bacterium was first discovered, it was classified as a virus. However, it was later re-classified as a bacterium. Which of the following is the most likely reason why C. trachomatis was reclassified as a living bacterial cell as opposed to a nonliving viral particle?

Chlamydia trachomatis is capable of performing metabolic processes.

Which of the following prion diseases is found in deer and elk?

Chronic wasting disease

Choose the true statement about the epigenome.

DNA methylation patterns of the epigenome can be inherited.

Which of the following is an example of a spontaneous mutation?

DNA polymerase III accidently mismatches a G to a T during Escherichia coli DNA replication, resulting in a silent mutation.

Which of the following is an unsuitable culture method for an animal virus?

Direct inoculation of virus onto blood agar

An elderly patient who contracted chickenpox as a child now has shingles as an adult. You explain to your patient that both diseases are caused by the same virus, which lays dormant in the body prior to reactivation. Based on this information, choose the true statement.

During dormant periods, the virus exists episomally inside of infected host cells.

Choose the TRUE statement about prokaryotic and eukaryotic DNA replication

Eukaryotic DNA replication begins at multiple origins of replication, while prokaryotic DNA replication begins at a single origin of replication.

Oncogenic viruses, such as certain human papillomaviruses (HPVs) cause cancers. What is the most likely mechanism that certain HPVs use to promote cancer?

HPVs are likely induce recombination to promote cancer.

While hiking, your patient was bitten by a rabid raccoon. Your patient denies having any previous rabies vaccinations. Which of the following antiviral medications should be administered to your patient to prevent viral attachment to host cells?

HRIG

Put the following enzymes in the order they participate in the DNA replication, from beginning to end. - SS binding proteins - DNA polymerase III - Helicase - Primase

Helicase, SS binding proteins, primase, DNA polymerase III

Your elderly patient is affected by shingles. After careful observation, you note that the virus responsible for the infection has an icosahedral capsid, is enveloped, and has double-stranded linear DNA as its genetic material. Based on this information, in which of the following viral families would you group this viral pathogen?

Herpesviridae

Choose the true statement about Hfr strains.

Hfr strains result when the fertility plasmid integrates into the host chromosome.

Choose the true statement about housekeeping genes in Escherichia coli.

Housekeeping genes are constitutively expressed.

A young patient who underwent surgical placement of depth electrodes for epilepsy treatment contracted a prion disease. Cortical electrode probes are known to be reused in patients. Based on this information, which of the following prion diseases did the young patient most likely contract?

Iatrogenic Creutzfeldt-Jakob Disease

Which of the following is an example of phage conversion?

Infection of Streptococcus pyogenes with T12 phage enables the bacteria to produce erythrogenic toxins, allowing it to cause scarlet fever.

Which of the following describes how 5-bromouracil might create a mutation?

It can replace the base thymine, and can base pair with guanine rather than adenine.

The anticodon of a tRNA molecule is 3' - GUA - 5.' This tRNA molecule should allow which amino acid to be incorporated into a growing protein chain? (Use the following condensed mRNA codon table to assist you with this question). 5' - GUA - 3' - Valine 5' - UAC - 3' - Tyrosine 5' - AUG - 3' - Methionine 5' - CAU - 3' - Leucine

Leucine

Azathioprine is a drug that may be prescribed to transcript recipients to reduce the chance of tissue rejection reactions. In its active state, it acts as a purine analogue, inhibiting DNA biosynthesis. This means that 6-mercaptopurine will be inserted in place of a purine containing nucleotides during DNA replication. Given this drugs mode of action, you would expect it to be incorporated into DNA in place of:

Nucleotide containing adenine or guanine

Which of the following is a valid difference between the leading and lagging strands in DNA replication?

On the leading strand, only a single RNA primer is needed to initiate continuous DNA synthesis.

A nurse experienced an accidental needle stick while treating a patient who has hepatitis C. The seroconversion window for hepatitis C is approximately 6-8 weeks. Given this information, which of the following viral detection methods would be most appropriate for detecting a hepatitis C infection in the nurse one week following the needle stick?

PCR-based detection of hepatitis C RNA

You wish to culture and quantify T4 bacteriophages. Which of the following techniques would be the most relevant?

Perform a plaque assay using the bacterium Escherichia coli.

From which phrase is the term "prions" derived?

Proteinaceous infectious particles

According to the animation, which of the following makes mRNA from the information stored in a DNA template?

RNA polymerase

Which of the following is NOT an enzyme involved in DNA replication?

RNA polymerase

Choose the correct statement about viral evolution.

RNA viruses mutate faster than DNA viruses due to a lack of proofreading replicative enzymes.

Retroviruses, such as human immunodeficiency virus, rely on reverse transcriptase to multiply inside a cell. However, HIV also requires host ribosomes to build new viral particles. Based on your knowledge of the central dogma, order the flow of genetic information from left-to-right, from the first step (left) to the last step (right), for retroviruses.

RNA, DNA, RNA, Protein

Assume the operator for the E. coli arginine operon was removed. What direct effect would this have on the expression of genes required to build arginine?

Removing the operator would mean that expression of arginine biosynthetic genes persists when arginine is abundant.

How do retrotransposons differ from DNA transposons?

Retrotransposons rely on reverse transcriptase for transposition, while DNA transposons do not.

Which disease did Stanley Prusiner first identify as being caused by prions?

Scrapie

Which of the following genome types has been observed in viruses?

Single-stranded DNA Single-stranded RNA Double-stranded RNA

Choose the TRUE statements about protein synthesis:

The first amino acid in a eukaryotic protein is methionine, whereas the first amino acid in a prokaryotic protein sequences is formyl methionine

Choose the true statement about the genetic code.

The genetic code is redundant, with multiple codons specifying a single amino acid.

Which of the following is a key difference between lytic and lysogenic bacteriophage replication cycles?

The lytic replication cycle ends with host cell lysis and release of newly formed bacteriophage particles, whereas lysogenic replication leads to prophage formation.

You are studying an unknown virus that does not perform transcription to make viral proteins. Which of the following characteristics must also be true for this unknown virus?

The virus has a positive, sense-stranded RNA genome.

You observe that a novel virus penetrates the host cell through membrane fusion. Which of the following statements must also be true regarding this virus and its replicative cycle?

The virus releases from host cells by budding.

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

The virus would not be able to infect new hosts.

How are prions different from other infectious agents?

They lack nucleic acid.

How are viruses different from eukaryotic cells?

They require a host to reproduce

Choose the true statement about pre-transcriptional regulation.

This form of regulation controls when and how often RNA is produced from a DNA template.

What is the function of the structural elements of a virus?

To package and protect the viral genome

Which of the following is (are) used to classify viruses? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.

Type of nucleic acid present Capsid symmetry

Which of the following conditions in humans is linked to bovine spongiform encephalopathy?

Variant Creutzfeldt-Jakob disease

Which of the following best describes a prophage?

When a phage genome is integrated into the host cell's chromosome

In the Spring of 2009, a novel H1N1 virus emerged that had a new combination of genes from pigs, humans, and birds. As a result, the virus spread quickly, resulting in a swine flu pandemic. Which of the following concepts explains why the outbreak occurred?

antigenic shift

In which stage does formation of mature viruses occur?

assembly

Which of the following is not a mechanism for horizontal gene transfer?

binary fission

The host DNA is usually degraded during which stage?

biosynthesis

A nucleotide-altering chemical

can alter nitrogenous bases of DNA, resulting in incorrect base pairing.

Compared to eukaryotic genomes, only prokaryotic genomes:

contain usually one, circular chromosome.

Bacterial cells use DNA replication to:

copy their genetic material prior to binary fission

Your patient has purple, red, and brown lesions on the legs, indicative of Kaposi sarcoma. Given this observation, which of the following oncogenic viruses is most likely present in your patient?

human herpes virus 8

Mutagens

increase the likelihood of mutations in DNA.

Which of the following prion diseases was also known as laughing disease?

kuru

Which of the following can be translated into protein?

mRNA

Transcription produces which of the following?

mRNA, tRNA, rRNA

Thymine dimers result from

nonionizing radiation

At what site on the chromosome does DNA replication begin?

origin of replication

In which stage is the viral DNA introduced into the cell?

penetration

You observe that when you grow Serratia marcescens at human body temperature, the resulting bacterial colonies appear white. However, when you grow the same bacterium at room temperature, the colonies that grow are red. This difference in pigmentation is best described as a ____________.

phenotype difference

What results from the process of translation?

polypeptide

Ribosomes contain which of the following?

rRNA

Which of the following is an example of a post-transcriptional regulation mechanism?

riboswitches

Liver cells and skin cells in the same individual are structurally and functionally different despite having the same genomic information. Their differences are attributable to:

the extent to which specific genes are expressed in the given cell types.

The rabies virus primarily affects the nervous system. The specificity that the rabies virus has for neuronal host cells is primarily dictated by __________________________.

the spikes that protrude from its viral envelope

DNAase is an enzyme that degrades free DNA in the environment. Which horizontal gene transfer process would you expect DNAase to possibly disrupt?

transformation

RNA is distinguished from DNA because only RNA:

typically exists as a single-stranded molecule.