BCH 3170 Study Guide - Lambda Phage, Antitermination, Gene Expression

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26 Nov 2014

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Lytic: leads to production of new lambda phage particles. Host destruction occurs: phage attaches to the bacteria (e. coli) in this case and inject genetic material in the host, phage dna is then circularized. There are two options: go through lytic mode- lambda dna is replicated multiple copies of phage dna in host. Genes in phage lambda will be expressed and proceed to synthesis all lambda phage proteins required for the production of complete phage particles: at some point: cell lysis occurs, destroying host e-coli and release phage particle. Lysogenic: lambda dna integrated into host (e-coli genome): phage attaches to bacteria-infection. Tow modes are different, but bacteria can go from lysogenic to lytic. But once lytic mode is engaged and phage particle production starts-no possibility for this bacteria to enter lysogenic mode. E-coli induction and two anti-terminators important for the expression of: name two repressors phage lambda genes and briefly explain the mechanisms of repression and anti-termination.

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I need help.

what could be a mechanisms for the phage induction process exit from the genome?

It has been observed that bacteriophages, like the lambda phage, that have integrated into their host genome (prophage) are induced to cut themselves out of the genome when exposed to DNA damage. Prophage are able to remain in the genome by producing a single repressor protein that keeps the genes turned off that are normally used in replication and for the production of structural proteins during active phage amplification. From your knowledge of the induction of cellular repair, propose a mechanism for the phage induction process to exit from the genome.

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

BCH 3170 Study Guide - Lambda Phage, Antitermination, Gene Expression

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