Biology 1202B Chapter Notes - Chapter 11: Chromosome, Inverted Repeat, Prophage

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25 Apr 2018

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Cycle 11 viruses, retroviruses, and repetitive dna. Although they are not considered to be alive, they are still classified into orders, families, genera, and species: using virus size, structure, genome structure (rna or dna, single stranded or double stranded), how nucleic acid is replicated. Not all viruses are pathogens many viruses actually benefit their hosts: ex. Infection by certain nonpathogenic viruses protects human hosts against pathogenic viruses. 23. 2 viruses infect bacterial, animal, and plant cells by similar pathways. Virulent bacteriophages: kill their host cells during each cycle of infection. Temperate bacteriophages: enter an inactive phase inside the host cell and can be passed on to several generations of daughter cells before becoming active and killing their host. In the type of transduction described above, bacterial genes form essentially and dna fragment can be randomly incorporated into phage particles: gene transfer by this mechanism is termed generalized transduction.

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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

2.)

a.) Are viruses that infect Archaea different from other bacterial viruses?

Yes, they do not have protein coats because of the extreme conditions where they live.

No, they consist of nucleic acid and protein just like other bacterial viruses.

Yes, the structure of archaeal viruses is always completely different from other bacterial viruses.

Yes, they have only DNA genomes.

b.) Of the following examples, which is not a common part of many viral life cycles?

The pox virus genome is replicated by DNA polymerase.

Adenoviruses attach to the cell and the nucleocapsid is taken up by the cell.

Pox viruses replicate in the cytoplasm of the cell.

Once an adenovirus virion is inside a cell, host RNA polymerases transcribe early genes

c.) Some viruses are associated with cancer. There are a variety of ways in which viruses may affect a cell in a way that may lead to cancer. Based on your knowledge of the life cycles of viruses and of molecular genetics, what is one way that this might happen?

Viral genetic material inserts into a host genome close to the termination sequence, far downstream of the promoter, and causes a silent mutation.

Viral genetic material inserts into a host genome in a repetitive noncoding region.

Viral genetic material inserts into a host genome, placing a promoter in a new location and turning on a gene that had previously been turned off.

Viral genetic material inserts into a host genome and causes a mutation in a promoter, turning off a gene that had previously been turned on.

d.) Which statement describes the difference between the normal neuron protein PrP^C and the pathogenic version PrP^Sc?

PrP^C is just a protein and the PrP^Sc is a protein with nucleic acid inside.

The PrP^C protein contains more beta sheets while the PrP^Sc protein contains more alpha helices.

The three-dimensional conformation is identical, but the amino acid sequence is different.

The amino acid sequence is identical, but the three-dimensional conformation is different.

1- An early test to determine if a virus was causing an illnessinvolved passing filtered fluid from one host to the next aftergreat dilution. What did this approach (serial dilution)demonstrate about the agent causing the illness?

2- what is the difference between the eclipse phase and thelatent phase of the virus replication cycle?

3- How are virus capsid proteins limited by the coding potentialof their nucliec acid, and how do they overcome thislimitations?

4- You are working in a lab and isolate a brand new virus. Youanalyze the nucleotide composition and determine the bases are inthe following proportions:

G: 30% T: 40% C:20% A:10% what type and strandedness of nucleicacid does it likely contain? what Baltimore class is it?

5- What is the difference between a satellite nucleic acid and aviroid?

6- Explain how an enveloped virus enters a cell by fusion.

7- What are the three functions of enzyme reversetranscriptase?

8- Some RNA viruses don't package an RNA-dependent RNApolymerase in their particle. How do they replicate? what typ ofvirus does this (nucleic acid type, strandedness, and sense)?

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Biology 1202B Chapter Notes - Chapter 11: Chromosome, Inverted Repeat, Prophage

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