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What shapes can a virus be and what determines its shape?
Icosahedral (isometric), helical, or complex. It is determined by its capsid.
Describe spikes and their function.
They are protein projections on the surface of a virus that are involved in attachment to the host cell.
Viruses can live outside or inside cells; what state are they in respectfully?
Outside of living cells, viruses are metabolically inert.
List the correct order for the stages of a phage infection.
Attachment, penetration, transcription, replication of nucleic acid and protein, assembly, and release.
*A surprisingly relatively recent finding is that, in the ocean..
Bacteria and viruses occur in much larger numbers than originally thought.
Probably keep the numbers of bacteria in check and are active in passing DNA from one bacterium to another.
*A phage that replicates inside the host cell and then lyses its host during its release is a..
*Phages that can either replicate and cause cell lyrsis or can integrate their DNA into the host DNA are called
*During attachment of phage to E. coli, the phage
Randomly bump into the bacteria and attach to proteins or carbohydrates on the bacterial surface
*What part of the E. coli T4 phage attaches to the host cell receptors?
Protein fibers at the end of the phage tail.
*During penetration of E. coli by the T4 phage..
the tail acts as a "hypodermic needle", injecting the phage DNA into the cell.
*Phage-induced enzymes are ..
Produced in a sequential manner and used to customize the cell for viral production.
*the process of separate replication of viral protein and its nucleic acid is termed..
*A positive-sense strand of RNA..
Is the only form of RNA found in phages and acts directly as mRNA.
*In the replication of phage containing positive-sense RNA,..
a phage-encoded RNA polymerase is used to make negative-sense RNA using the phage positive-sense RNA as a template.
Describe phage replication.
The majority of phages are temperate. When integrated into host DNA, the phage DNA is called a prophage. Lambda is a good example of a temperate phage.
*A temperate phage..
May be lysogenic and chooses between lysogenic and lytic cycles shortly after entering the host cell.
*The integration of phage DNA into the bacterial chromosome occurs because of..
Identical DNA sequences in both.
*Once integrated, phage DNA can remain in the prophage state as long as..
Certain phage genes are repressed.
*The activation of the SOS system in a bacterium infected with a prophage results in..
Complete lysis of the bacterial culture and destruction of the viral repressor through host protease activity.
*The phenomenon responsible for the ability of Corynebacterium diptherium to produce the virulent toxin responsible for the devastating effects of diptheria is called
*Which of the following organisms does not have its virulence increased by lysogenic conversions?
*The bacterial viruses that are released by a process terms extrusion are called..
*Transducing virulent phages do not lyse the cells they invade because..
Bacterial DNA has replaced critical viral DNA in the phage.
What is/are the limiting factor(s) for viral infection?
The presence of specific receptor molecules on the host cell.
*If the infecting phage lacks some critical pieces of DNA necessary for replication it is called..
Involves the transfer of a few specific genes, utilized a defective virus, and only involves genes near the viral DNA integration site.
*Isometric phages such as phi X174..
Synthesize double-stranded DNA and single-stranded DNA, go through a lytic life cycle, and carry a positive single-strand of DNA.
The integration of phage DNA into host DNA occurs in much the same fashion as seen in transformation, transduction, or conjugation.
The restriction-modification system always has two genes involved, the cutting enzyme and the methylating enzyme.
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