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Biology 1202B Lecture Notes - Lecture 21: Prophage, Reverse Transcriptase, Dna Polymerase

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erinfox426
27 Mar 2017
School
Western University
Department
Biology
Course
Biology 1202B
Professor
Jennifer Mc Donald

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Document Summary

Reverse transcriptase can synthesize the molecule in any direction. The virus uses the host cell to do everything. The rna genome is transcribed and ready to be packaged. It encodes the proteins that make it necessary to emerge from the cell. Hiv has the ability to bud out of the cell. It is beneficial for the retrovirus to stay alive. Targets the cells that are responsible for removing viral invaders. This compromises the ability for the individual to fight that virus. Reverse transcriptase has no proof-reading ability and is very error prone. The immune system is unable to recognize the new version of the virus. Rna viruses have the highest rate of mutation. If there are many copies of the virus, there will be a lot of opportunity for recombination. Hidden inside cells and largely use host cell machinery. The bacteriophage comes w/ its own dna polymerase that is different from the bacteria"s.

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Related Questions


1
Which of the following is a component of the HIV virus ?
A
DNA
B
Capsid
C
Nucleus
D
CD4 receptor
Answered
Change your responses to resubmit
2
Assigned as
Homework
2
What is the function of Reverse Transcriptase?
A
To insert the viral RNA into the host DNA.
B
To make an RNA copy of the viral RNA.
C
To make an RNA copy of the viral DNA.
D
To make a DNA copy of the viral RNA.
E
To insert the viral DNA into the host DNA.
Unanswered
Submit
3
Assigned as
Homework
3
Which of the following stages describes a HIV patient in who has a large number of severe opportunistic infections?
A
Primary HIV infection-lasts for a few weeks
B
Clinically asymptomatic stage-lasts for an average of ten years
C
Symptomatic HIV infection
D
Clinical AIDS
Unanswered
Submit
4
Assigned as
Homework
4
Which of the following individuals should be tested for HIV?
A
A newborn child
B
Alex, who studies excessively
C
Sarah, who takes birth control
D
Joe, who uses intravenous steroids
Unanswered
Submit
5
Assigned as
Homework
5
Harry engaged in risky activity that may have lead to exposure to HIV. Two and a half weeks later, he had an HIV test done and it showed a positive result. Which test most likely was done?
A
CD4 test
B
HIV antibody test
C
PCR test
D
Viral load test
Unanswered
Submit
6
Assigned as
Homework
6
How does an Integrase inhibitor work against the HIV virus?
A
It inhibits the generation of viral DNA from viral RNA.
B
It prevents the entry of HIV into the host cell.
C
It inhibits viral proteins from being inserted into new virus particles.
D
It prevents viral DNA from being inserted into host DNA.
E
It prevents the generation of new viral proteins.
Unanswered
Submit
7
Assigned as
Homework
7
How does a Protease inhibitor work to treat HIV infection?
A
It prevents the release of new viral particles.
B
It cleaves viral proteins interfering with their function.
C
It prevents the cleavage of host DNA preventing viral DNA from being inserted into host DNA.
D
It cleaves Reverse transcriptase preventing the generation of viral DNA.
E
It prevents the binding of gp120 to the CD4 protein.
Unanswered
Submit
8
Assigned as
Homework
8
Which of the following describes a combination therapy for HIV infected persons?
A
A preparation used for stimulating a viral response in the body.
B
A single drug given to HIV infected people since interactions with other medications may promote complications in treatment.
C
A drug cocktail-or-combination of antiviral drugs given to HIV infected people since they can be more effective than when given individually
D
A preparation used for stimulating an immune response in the body.
Unanswered
Submit
9
Assigned as
Homework
9
answerable question reference
For HIV to reproduce, which of the following is most critical?
A
Infecting new subjects
B
Producing a Provirus
C
Entering the host cells
D
Taking over the function of DNA in the cell
Unanswered
Submit
10
Assigned as
Homework
10
HIV is a virus which has the following characteristic?
A
It takes of the RNA of the host cell which subsequently by way of transcription and translation makes new virus
B
It attacks the RNA of the host cell causing cellular death
C
It attacks the DNA of the host cell causing cellular death
D
It takes over the DNA of the host cell which subsequently by way of transcription and translation makes new virus

Question 1 10 pts

What three kinds of cells are infected by HIV?

macrophages, T-Helper cells and dendritic cells

B-cells, skin cells and T-helper cells

B-cells, T-Helper cells and T-killer cells

macrophages, dendritic cells and cytotoxic T-cells

Question 2 10 pts

Sometimes an HIV infected cell is not killed immediately after infection, but lives on, and continues to be a source of the infection for the lifetime of the patient. What is the mechanism that allows the HIV virus to remain in the cell, to get passed down to all descendants of that cell, and to retain the ability to be reactivated for the lifetime of the patient?

Question 3 10 pts

List the three processes that viruses are dependent on their host cells for.

1.

2.

3.

Question 4 10 pts

What does the ELISA test for HIV infection measure?

HIV-specific antibodies

Hepatitis B-specific antibodies

circulating HIV particles

HIV-specific DNA

Question 5 10 pts

What is the cell surface receptor for HIV?

CD4

CD8

MHCII

HIV

Question 6 10 pts

What is the likely origin of HIV-1?

infection of humans by a simian virus native to the chimpanzee

germ warfare research by the CIA

sexually transmitted to humans through relations with sheep

a new human-chimpanzee hybrid virus accidentally made in a laboratory with recombinant DNA

Question 7 10 pts

How does AZT block the production of infectious virus?

It acts as a substitute for a DNA nucleotide that can only be inserted by the viral reverse transcriptase. The presence of the AZT in the DNA aborts the production of new viral DNA.

It directly blocks the reverse transcriptase.

It blocks the protease that cuts apart the three viral proteins, which is a necessary step during viral synthesis.

It blocks the adsorption of the virus to the CXCR4 and CCR5 receptors on the T-cell surface.

Question 8 10 pts

How do protease inhibitors work?

It blocks the protease that cuts apart the three viral proteins, which is a necessary step during viral synthesis.

It directly blocks the reverse transcriptase.

It acts as a substitute for a DNA nucleotide that can only be inserted by the viral reverse transcriptase. The presence of the AZT in the DNA aborts the production of new viral DNA.

It blocks the adsorption of the virus to the CXCR4 and CCR5 receptors on the T-cell surface.

Question 9 10 pts

What are the 2 most common causes of a false negative result in the HIV test?

1.

2.

Questions 10-13

The next set of 4 questions deal with the possible ways that a virus, not necessarily the HIV, can enter the body. Answer TRUE or FALSE to each question.

Question 10 2.5 pts

Some viruses can enter the body through breaks in the skin.

True

False

Question 11 2.5 pts

Some viruses can enter the body through the anal/genital tract.

True

False

Question 12 2.5 pts

Some viruses can enter the body through the oral cavity and the digestive tract.

True

False

Question 13 2.5 pts

Some viruses can enter the body through inhalation via the respiratory tract.

True

False

Below is a paragraph describing HIV infection as they relate to the progress of infection. Please help choose the correct answer in each parentheses.

HIV initially infects (CD4+, or CD8+, or B) cells. These are helper T cells that activate (CD4+ or ,CD8+ or, B) cytotoxic T cells and (CD4+, or CD8+, or B) cells which produce antibodies. If HIV kills (CD4+, or CD8+) T cells then they cannot to do their job of activating these cells thus causing HIV infected people to be immunocompromised. Sometimes HIV infected people enter a latency period where the virus is inactive. This latency period can last for several years. During latency HIV (DNA, or RNA) becomes integrated into the (CD4+ or CD8+, or B) host cells genome and stops producing viral HIV RNA and new HIV virions. However, for some unknown reason, HIV comes out of dormancy and the viral (RNA, or DNA ) that was integrated in the (CD4+ , or CD8+,) T cell genome begins to transcribe more viral (DNA , or RNA) to make more viral (DNA, or RNA) using the host cells machinery. The viral (DNA, or RNA) then gets translated by host cell ribosomes to make viral proteins that eventually become packaged into new HIV virions. Consequently, after the latency period HIV becomes activated in the host cell. These cells present HIV antigen on their cell surface and alert (CD8+ or CD4+ or B) cells to kill them. As they are killed the infected (CD4+, or CD8+, or B) cells release the HIV virions into the blood stream to infect other (CD4+ or CD8+) cells such as macrophages and dendritic cells. This explains why after latency we see (CD4+, or CD8+) T cells continue to decrease while at the same time viral (DNA, or RNA) levels increase.

Based on your answers to the fill in paragraph, which statement is true?

A. Once active in CD8+ T cells, HIV can now replicate with impunity and infect other cells which explains the increase in HIV RNA after latency.

B. The increase in active HIV after latency accounts for why HIV can remain dormant for years after the initial infection.

C. CD4+ levels stabilize after the latency period and explain why there is little increase in HIV RNA levels.

D. Opportunist infections can occur after HIV latency because there are very few helper T cells to left to activate cytotoxic T cells and B cells to mount an immune response.