Video trivia
Define the lytic cycle
The lytic cycle includes the replication of the genetic material and the viral proteins, but above all, the virus overload causes the cell to lyse (burst)
What is the main difference between a + sense RNA virus and a - sense RNA virus?
The + sense RNA virus can make viral proteins right away. The - sense RNA virus must (with the help of an enzyme) synthesize a + RNA sense virus to produce viral proteins.
What enzyme is included with the viral RNA?
Reverse transcriptase.
Why is the mutation rate lower for DNA viruses?
The host cells have the machinery to proofread errors when copying DNA.
Define the lysogenic cycle
The blending of the viral genetic material with the host's genetic material.
Why is the mutation rate much higher in RNA viruses than DNA viruses?
Even the host cell does not provide the machinery to proofread the bases on the RNA strand. Therefore errors are more common when synthesizing a - RNA from a + RNA and vice versa.
What intermediate does the reverse transcriptase help to build?
Double stranded DNA.
What are the advantages of storing viral DNA in the host cell nucleus?
The nucleus also has a membrane which protects the viral DNA from enzymes outside of the nucleus.
Why can a viral envelope be helpful to the virus?
The viral envelope includes a phospholipid bilayer which can help the virus break through the host cell membrane better since the host cell membrane also has a phospholipid bilayer.
How does a + RNA and a - RNA make a copy of itself?
The + RNA is used as a template to make - RNA which is then used as a template to make + RNA.
The - RNA is used as a template to make + RNA which is then used as a template to make - RNA.
Why are relatively few T helper cells infected at the start of an infection with HIV?
Although T helper cells can undergo mitosis during the inactive stage of the infection, the mitosis rate is relatively low during the early stages.
Which strand of the DNA is used as a template to make + sense RNA?
The - sense strand.
During the lysogenic cycle how can the virus still be spread to other cells?
The cell whose genetic material includes the viral genetic material undergoes mitosis.
Why is the RNA virus less stable than the DNA virus?
The classic + or - sense RNA is single stranded and doesn't experience the hydrogen bonding which occurs between the base pairs in the double stranded DNA.
Why are reverse transcriptase inhibitors one example of HIV treatment?
Reverse transcriptase inhibitors get in the way of making viral DNA from the viral RNA so the viral DNA cannot blend with the host DNA.
Why is heat often used to inactivate DNA viruses?
The heat breaks the hydrogen bonds in DNA
What causes the bacteria which causes cholera to become particularly deadly to a host?
The bacteria could be infected with the bacteriophage CTX (bacteriophage is a virus which targets bacteria). In defense, the bacteria could release a toxin which is deadly to the host.
In one of the videos, mRNA (+ RNA) was shown to bind to a ribosome in preparation for protein synthesis. How could a double stranded RNA affect protein production if it binds to a ribosome?
The hydrogen bonding between the + and - RNA strands might get in the way of reading the + RNA strand as the protein is being assembled.
Why is CRISPR a more promising form of treatment against HIV?
The viral DNA can be removed from the host's DNA.
Although DNA viruses have lower mutation rates than RNA viruses, name a particular advantage (for the virus) of having DNA as its genetic material.
The host cell's machinery is more likely to be able to make copies of DNA or transcribe DNA into RNA effectively.