BIOL 141 Chapter 15: DNA and the Gene Synthesis and Repair

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7 Dec 2017

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Chapter 15: dna and the gene: synthesis and. Viruses inject genes into bacterial cells and leave a capsid behind. Start of infection virus genes inter host cell, capsid does not. Production of new virus particles directed by virus genes. End of infection new generation of virus particles burst from host cell. Capsid: a shell of protein enclosing the genome of a virus particle. All the radioactive protein was outside the cell in the emptied capsids. All the radioactive dna was inside the host cells. Because the injected component of the virus directs the production of a new generation of virus particles, this component must represent the virus" genes. Lead to acceptance that dna, not protein, is hereditary material. Claimed that dna contained all the information for life"s complexity. A backbone of sugar and phosphate groups of deoxyribonucleotide monomers. A series of bases that project from the backbone.

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QUESTION 1: The rabies virus primarily affects the nervous system. The specificity that the rabies virus has for neuronal host cells is primarily dictated by __________________________.

A. the helical shape of its viral capsid

B. the type of nucleic acid used for its viral genome (single-stranded, antisense RNA)

C. the spikes that protrude from its viral envelope

D. the segmented nature of its viral genome

QUESTION 2: Which of the following genome types has been observed in viruses? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

A. Single-stranded RNA

B. Single-stranded DNA

C. Double-stranded RNA

D. Protein-based

QUESTION 3: Choose the correct statement about viral evolution.

A. RNA and DNA viral genomes evolve at equal rates.

B. Cellular genomes mutate at a faster rate than viral genomes due to their large size and increased chance of replicative mistakes.

C. DNA viruses mutate faster than RNA viruses because thymine is more susceptible to mutation than uracil.

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

QUESTION 4: 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?

QUESTION 5: Which of the following is a key difference between lytic and lysogenic bacteriophage replication cycles?

A. Lysogenic bacteriophages release via host cell lysis, whereas lytic bacteriophages bud off from the host cell membrane.

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

C. Lytic replication requires an uncoating step, whereas in lysogenic replication, the bacteriophage's nucleic acid is directly injected into the host cell.

D. Whereas lytic replication enables the infection of several hosts, lysogenic replication only allows for infection of a single host cell.

QUESTION 6: Which of the following is an unsuitable culture method for an animal virus?

A. Direct inoculation of virus onto blood agar

B. Live animal inoculation

C. Tissue culture method

D. Injection of virus into embryonated eggs

1. Select all of the true statements regarding phageconversion.

-The incorporation of viral genesinto the host cell's DNA is an example of phage conversion.

-The expression of the incorporatedgenes and the resulting alteration of the bacterial phenotype is anexample of phage conversion.

-Cholera toxin genes have a viralorigin.

-The cholera toxin is produced bythe virus.

-The cholera toxin itself is transferred to Vibriocholerae by a virus.

2. Viruses grown in media with radioactive sulfur haveradioactive capsids. Why?

Nucleotides contain sulfur

Cysteine amino acids containsulfur

Capsid peptidoglycans containsulfur

Phospholipids contain sulfur

3. Integrase inhibitors work by:

Agglutinating the reversetranscriptase inhibitors

Preventing the incorporation of theviral DNA into the genome

Blocking the final viralassembly

Degrading the viral envelope

4. Once a prophage is formed, the viral genes are reproducedevery time the bacterium multiplies. The genes that encode thelytic cycle are held in check by a repressor protein. Stressinduces the formation of proteases that degrade the repressor. Howwould this affect the prophage?

Apoptosis would be induced.

The virus enters the lyticcycle.

The bacterial genome isdenatured.

The bacterium rejects the viral genes.

5. Can a virus be killed?

No, viruses are non-living andcannot die.

No, viruses are capable ofself-assembly and cannot be permanently killed.

Yes, separating the genes from thecapsid kills it.

Yes, destroying its genome kills it.

6. Which class of drugs would be effective against HIV but notagainst most other pathogenic viruses?

Translation inhibitors that stopassembly of viral proteins.

Nucleotide analogs that haltreplication.

Non-nucleoside reversetranscriptase inhibitors that block reverse transcription.

Receptor antagonists that block viral entry.

7. An unscrupulous malcontent writes a computer program andembeds it in an e-mail that promises lucrative investmentopportunities. The e-mail is sent to thousands of anonymous users,when they open it the program copies itself into the computer'shard drive. The hard drive begins to fill up with copies of theprogram, once it is completely full the computer crashes. Match thecomponents of this story with the components of a viral lifecycle.

1. e-mail containing virus	Virus
2. Innocent user	Binding site onhostcell
3. User's hard drive andCPU	Host cell'sribosomes
4. Program	Uninfected host cell

8. Vaccines work by priming the immune system and inducing theformation of antibodies and memory cells. When the actual virusinfects the host the host's immune system recognizes it andresponds to it. Which feature of viruses helps them thwart thissystem?

	The envelops prevents immune systemrecognition.
	Autocatalytic proteins replicatewithout genetic material.
	The high mutation rate of the viralgenome.
	Integration of viral genescamouflages the virus.
	Shedding the capsid inactivates theantibodies.

greensea-lion551

1
Which of the following is a component of the HIV virus ?
A
DNA
B
Capsid
C
Nucleus
D
CD4 receptor
Answered
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2
Assigned as
Homework
2
What is the function of Reverse Transcriptase?
A
To insert the viral RNA into the host DNA.
B
To make an RNA copy of the viral RNA.
C
To make an RNA copy of the viral DNA.
D
To make a DNA copy of the viral RNA.
E
To insert the viral DNA into the host DNA.
Unanswered
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3
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3
Which of the following stages describes a HIV patient in who has a large number of severe opportunistic infections?
A
Primary HIV infection-lasts for a few weeks
B
Clinically asymptomatic stage-lasts for an average of ten years
C
Symptomatic HIV infection
D
Clinical AIDS
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4
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4
Which of the following individuals should be tested for HIV?
A
A newborn child
B
Alex, who studies excessively
C
Sarah, who takes birth control
D
Joe, who uses intravenous steroids
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5
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5
Harry engaged in risky activity that may have lead to exposure to HIV. Two and a half weeks later, he had an HIV test done and it showed a positive result. Which test most likely was done?
A
CD4 test
B
HIV antibody test
C
PCR test
D
Viral load test
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6
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6
How does an Integrase inhibitor work against the HIV virus?
A
It inhibits the generation of viral DNA from viral RNA.
B
It prevents the entry of HIV into the host cell.
C
It inhibits viral proteins from being inserted into new virus particles.
D
It prevents viral DNA from being inserted into host DNA.
E
It prevents the generation of new viral proteins.
Unanswered
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7
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7
How does a Protease inhibitor work to treat HIV infection?
A
It prevents the release of new viral particles.
B
It cleaves viral proteins interfering with their function.
C
It prevents the cleavage of host DNA preventing viral DNA from being inserted into host DNA.
D
It cleaves Reverse transcriptase preventing the generation of viral DNA.
E
It prevents the binding of gp120 to the CD4 protein.
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8
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8
Which of the following describes a combination therapy for HIV infected persons?
A
A preparation used for stimulating a viral response in the body.
B
A single drug given to HIV infected people since interactions with other medications may promote complications in treatment.
C
A drug cocktail-or-combination of antiviral drugs given to HIV infected people since they can be more effective than when given individually
D
A preparation used for stimulating an immune response in the body.
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9
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9
answerable question reference
For HIV to reproduce, which of the following is most critical?
A
Infecting new subjects
B
Producing a Provirus
C
Entering the host cells
D
Taking over the function of DNA in the cell
Unanswered
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10
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10
HIV is a virus which has the following characteristic?
A
It takes of the RNA of the host cell which subsequently by way of transcription and translation makes new virus
B
It attacks the RNA of the host cell causing cellular death
C
It attacks the DNA of the host cell causing cellular death
D
It takes over the DNA of the host cell which subsequently by way of transcription and translation makes new virus

BIOL 141 Chapter 15: DNA and the Gene Synthesis and Repair

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