CH 461 Lecture Notes - Lecture 47: Hiv, Reverse Transcriptase, Ribonuclease H

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silvercicada472

19 Jul 2018

School

University of Alabama

Department

Course

CH 461

Professor

Dunkel

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Document Summary

Reverse transcription (which occurs in both prokaryotes and eukaryotes) is the synthesis of dna from an rna template. A class of rna viruses, called retroviruses, transcriptase). The virus that causes aids, human immunodeficiency virus (hiv), is a retrovirus. Because nuclear cell division doesn"t use reverse transcriptase, the most. Telomerase, discussed in the previous section, is a specialized reverse transcriptase enzyme dependent. They also possess an rnase h activity (h stands for hybrid) that can degrade the rna template after it is used for synthesis of the first dna strand. The are characterized by the presence of an rna dependent dna polymerase (reverse effective anti hiv drugs target reverse transcriptase, either its synthesis or its activity. Like other dna polymerases, reverse transcriptases are primer and template enzyme then can copy the first strand of dna to make a double stranded molecule. transcriptases don"t have an editing (3 5 ) exonucleolytic activity.

Related Questions

BIOCHEM QUESTIONS:

Question 1) (1.5 points) True or false: The initial native DNA is usually in an overwound state, making the initial strand separation during replication energetically favorable, with continued strand separation at the replication fork resulting in underwound DNA that is then fixed by DNA gyrase.

Question 2) (1.5 points) True or false: UV based DNA damage largely causes dimerization of C and T bases that are fixed by the NER DNA repair pathway.

Question 3) (1.5 points) True or false: There is no enzyme within humans that has a reverse transcriptase activity.

Question 4) (1.5 points) True or false: One reason why uracil is not observed in DNA is that deamination of cytosine would result in Uracil and therefore potentially changing a GC base bp to an AT bp after a couple of rounds of replication.

Question #5: (1 point) Which of these statements is correct about the RNA polymerase? a) It makes tRNA, mRNA and rRNA b) It uses an RNA template c) It uses ATP, CTP, GTP and TTP d) It requires a primer

Question #6: (1 point) RNA polymerase grows the RNA chain in the 3â to 5â direction. a) True b) False

Question #7: (1 point) The mRNA is copied from the template strand. The mRNA has the exact same nucleotide sequence of the non-template strand except for U instead of T. a) True b) False

Question #8: (1 point) Only a limited portion of the DNA strand is copied by RNA polymerase, and there are initiation and termination signals for transcription. a) True b) False

Question #9: (1 point) The hairpin loop is the only way to conduct transcription termination in Prokaryotes. a) True b) False

pinkkangaroo550

Please answer all

Why does a template-dependent DNA polymerase require a primer to initiate DNA synthesis?

	DNA polymerase require 5' phosphate to add a new nucleotide
	DNA polymerase require 3' hydroxyl group to add a new nucleotide

DNA polymerase require energy by hydrolizing the primers

Which of the following enzymes is template independent?

	Reverse transcriptase
	Klenow fragment

	DNA polymerase
	Terminal deoxynucleotidyl transferase

RNA polymerase

The natural function of a DNA ligase enzyme is:

	Joining together DNA sequences with compatible cohesive ends from two different organisms to yield a recombinant DNA molecule
	Sealing single stranded nicks in double stranded DNA molecules

	Joining together two blunt ended fragments of DNA within a cell
	Joining together two single stranded DNA molecules

The natural function of 3' -> 5' exonuclease activity of a DNA polymerase is to:

	Remove the 5' end of the DNA strand that is being copied
	Remove damaged nucleotide from the template strand

	Remove nucleotides from the end of DNA to generate blunt ends
	Remove incorrect nucleotides from the newly synthesized DNA

Which technique is used to resolve the different sizes of DNA fragments?

	Gene cloning
	PCR

	DNA sequencing
	Gel electrophoresis

Which of the following vectors does not contain bacterial origin of replication (oriC)?

	plasmid
	cosmid

	bacterial artificial chromosome
	lambda vector

Which process of bacteriophage is not used for gene cloning?

	Concatemer formation
	Lytic cycle

	Lysogenic cycle
	viral packaging

What vector would be best suited for creating a contig of bovine (cattle) chromosome 10?

	lambda vector
	Cosmid vector

	P1 vector
	Plasmid

E. coli takes up plasmid DNA by which of the following methods?

	Transduction
	Transformation

	Conjugation
	Transfection

The following times and temperatures are an example of the steps for PCR. You can use the Figure to help you answer the following questions.

Why is the first step is carried out at 94Â°C?

	To degrade the template
	To denature the template

	To activate the polymerase
	To facilitate the primer binding

What happens in the reaction when the temperature shifts to 55Â°C during cycling?

	the DNA polymerase will carry out DNA synthesis by extending the annealed primers
	the DNA polymerase will finish DNA synthesis

	the primers anneal to the single-stranded regions of the DNA
	the primers anneal to the double-stranded regions of the DNA

During cycling, what occurs when the temperature is at 72Â°C?

	the primers anneal to the double-stranded regions of the DNA
	the DNA polymerase will carry out DNA synthesis by extending the annealed primers

	the primers anneal to the single-stranded regions of the DNA
	the DNA polymerase will finish DNA synthesis

You designed a set of primers to amplify 1 kb DNA with polymerase chain reaction. By which cycle of polymerase chain reaction, we would expect to see the first double stranded DNA with expected size?

	The end of cycle 1
	The end of cycle 2

	The end of cycle3
	The end of cycle 4

1. A mutation in the gene encoding the integrase enzyme rendersthe protein non-functional. How would the affect the HIV infectioncycle?

Formation of the provirus would bestopped.

Reverse transcription would nolonger be possible.

The gp120 glycoprotein would nolonger be able to bind to the CCR5 receptor.

Cutting and assembling the capsid would be halted.

2. If the viral gene is AUGCCCAGG and the mRNA used to make theviral protein is UACGGGUCC, then the virus is a :

Negative strand RNA virus

Double stranded DNA virus

Retrovirus

Positive strand RNA virus

3. Would treating prions with enzymes that digest nucleotides bean effective neutralization method?

No, prions lack amino acids.

Yes, prion nucleic acids would besusceptible to enzymatic digestion.

No, prions lack phosphodiesterbonds and would not be subject to digestion by these types ofenzymes.

Yes, the bonds between the amino acids would be hydrolyzed.

4. Most Americans born before 1970 have a permanent scar ontheir shoulders from the smallpox vaccine. Why don't youngerAmericans have one?

Smallpox has been eradicated by aworldwide vaccination program.

Smallpox is no longer lethal.

A safer less damaging vaccine wasdeveloped in the early 1970's.

The vaccine is no longer effective due to antigenic shift.

5. What kind of pathogen would retain its ability to causeinfections after being treated with powerful proteolytic chemicalsthat would destroy all proteinaceous material?

A viroid

6. Select all of the false statements concerning AIDS.

AIDS kills the patient.

Patients die as a result ofopportunistic infections.

AIDS shuts down the immunesystem.

HIV therapy (HAART) can clear thevirus from the bloodstream.

HIV therapy (HAART) can clear the virus from the patient'sbody.

7. Why do viruses only infect specific types of cells?

Viruses only attack epithelialcells, such as the cells lining the lungs.

If a host cell is weakened, viruseshave an easier time infecting it.

The initial choice is random butonce a cell type is chosen it becomes the preferred host.

The host cells have the correctsurface receptor that the virus can fit into.

Viruses infect the first cells they encounter.

8. Nucleotide analogs are a class of drugs that are highlyeffective against many types of viruses. They work by halting thereplication of viral genes. They are equally effective at stoppingthe spread of prion diseases.

True

False

9. An experimental chemical has been shown to selectively cleavephosphodiester bonds. How would the affect a virus?

Dissociate the envelope

Fragment the genome

Hydrolyze the protein coating

Alter the host binding site

Digest the capsid

10. HIV uses cell surface receptors to enter host cells. Whydoes switching from a CCR5 co-receptor to a CXCR4 co-receptoreventually shut down the immune system?

	Macrophages have CCR5co-receptors.
	T-helper cells have CXCR4co-receptors.
	T-helper cells are not involved incoordinating immune responses.
	Only macrophages are killed byHIV.

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CH 461 Lecture Notes - Lecture 47: Hiv, Reverse Transcriptase, Ribonuclease H

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