Friday, 5 June 2015

Bacteriophages

Bacteriophages

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A bacterial defense mechanism against bacteriophage is called:

a. concatamerization
b. polymerization
c. restriction
d. lysogeny

Which of the following bacteria can be typed by phage typing method?

a. Staphylococcus aureus
b. Salmonella typhi
c. Vibrio cholerae
d. All of these

__________ protein keeps the prophage dormant and prevents virus.

reproduction.
a. Operator
b. Promotor
c. Repressor
d. Enhancer

The procapsid is assembled with the aid of __________ proteins.

a. ladder
b. framing
c. scaffolding
d. form

Contractile sheath of the tail is present in which of the following phages?

a. T3
b. T2
c. P22
d. All of these

The process by which phage reproduction is initiated in lysogenized culture is called

a. infection
b. integration
c. repression
d. induction

Area of lysis on a bacterial lawn culture produced by a phage is known as__________.

a. pock
b. plaque
c. pox
d. all of these

One of the first enzymes synthesized by many bacteriophage is __________, an RNA-dependent RNA polymerase.

a. RNA transcriptase
b. RNA polymerase
c. RNA ligase
d. RNA replicase

In viruses with envelopes__________.

a. the envelope and the embedded proteins are encoded by the viral nucleic acid
b. the envelope is derived from the host but it contains embedded proteins coded by the viral nucleic acid
c. the envelope is coded by the viral nucleic acids, but the proteins come from the host's membrane proteins
d. the envelope and its imbedded proteins are derived from the host's membranes

Which of the following is/are synthesized from late mRNA?

a. Phage structural proteins
b. Proteins that help with phage assembly without becoming part of the virion structure
c. Proteins involved in cell lysis and phage release
d. All of the above

Which capsid symmetry is exhibited by most of the phages?

a. Helical
b. Icosahedral
c. Complex
d. None of these

__________ is specifically able to have a long-term relationship with the host known as lysogeny.

a. Temperate virus
b. Adsorbed virus
c. RNA phage
d. DNA phage

Which of the following properties is due to lysogenic conversion by phages?

a. Toxin production in Corynebacterium diphtheriae
b. Toxin production in Clostridium botulinum types C and D
c. Antigenic variation in Salmonella anatum
d. All of the above

T-even phage binding to E. coli probably involves__________.

a. electrostatic interaction
b. hydrophobic interaction
c. covalent bonds
d. all of these

The filamentous bacteriopohage infect male E. coli cells by attaching to __________.

a. lipopolysaccharide
b. the cell wall
c. the tip of the pilus
d. the cell membrane

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