BIOL 1107 Chapter Notes - Chapter 15: Gamete, Dna Ligase, Okazaki Fragments

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29 Mar 2017

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Chromosomes are a complex of dna and proteins. Dna was known to be composed of just four types of deoxyribonucleotides. Question whether genes were made up of proteins or dna. During a t2 infection, the exterior protein coat, capsid, of the original parent virus is left behind. The capsid remains attached to the exterior of the host cell. T2 is made up almost exclusively of dna and protein. Hershey and chase"s strategy for determining the composition of the viral substance that enters the cell and acts as the hereditary material was based on two facts: If genes consist of dna, then radioactive protein should be found only in the capsids outside the infected host cells, while radioactive dna should be located inside the cells. If genes consist of proteins, then radioactive protein and no radioactive dna should be inside the cells.

Related Questions

1. Select all of the true statements regarding phageconversion.

-The incorporation of viral genesinto the host cell's DNA is an example of phage conversion.

-The expression of the incorporatedgenes and the resulting alteration of the bacterial phenotype is anexample of phage conversion.

-Cholera toxin genes have a viralorigin.

-The cholera toxin is produced bythe virus.

-The cholera toxin itself is transferred to Vibriocholerae by a virus.

2. Viruses grown in media with radioactive sulfur haveradioactive capsids. Why?

Nucleotides contain sulfur

Cysteine amino acids containsulfur

Capsid peptidoglycans containsulfur

Phospholipids contain sulfur

3. Integrase inhibitors work by:

Agglutinating the reversetranscriptase inhibitors

Preventing the incorporation of theviral DNA into the genome

Blocking the final viralassembly

Degrading the viral envelope

4. Once a prophage is formed, the viral genes are reproducedevery time the bacterium multiplies. The genes that encode thelytic cycle are held in check by a repressor protein. Stressinduces the formation of proteases that degrade the repressor. Howwould this affect the prophage?

Apoptosis would be induced.

The virus enters the lyticcycle.

The bacterial genome isdenatured.

The bacterium rejects the viral genes.

5. Can a virus be killed?

No, viruses are non-living andcannot die.

No, viruses are capable ofself-assembly and cannot be permanently killed.

Yes, separating the genes from thecapsid kills it.

Yes, destroying its genome kills it.

6. Which class of drugs would be effective against HIV but notagainst most other pathogenic viruses?

Translation inhibitors that stopassembly of viral proteins.

Nucleotide analogs that haltreplication.

Non-nucleoside reversetranscriptase inhibitors that block reverse transcription.

Receptor antagonists that block viral entry.

7. An unscrupulous malcontent writes a computer program andembeds it in an e-mail that promises lucrative investmentopportunities. The e-mail is sent to thousands of anonymous users,when they open it the program copies itself into the computer'shard drive. The hard drive begins to fill up with copies of theprogram, once it is completely full the computer crashes. Match thecomponents of this story with the components of a viral lifecycle.

1. e-mail containing virus	Virus
2. Innocent user	Binding site onhostcell
3. User's hard drive andCPU	Host cell'sribosomes
4. Program	Uninfected host cell

8. Vaccines work by priming the immune system and inducing theformation of antibodies and memory cells. When the actual virusinfects the host the host's immune system recognizes it andresponds to it. Which feature of viruses helps them thwart thissystem?

	The envelops prevents immune systemrecognition.
	Autocatalytic proteins replicatewithout genetic material.
	The high mutation rate of the viralgenome.
	Integration of viral genescamouflages the virus.
	Shedding the capsid inactivates theantibodies.

greensea-lion551

What step in DNA replication precedes the pairing of complementary bases?

	A.	polymerization of DNA.
	B.	formation of the histone core.
	C.	mitotic division.
	D.	separation of the two strands.
	E.	joining of the two strands.

In eukaryotes, transcription occurs in the

	A.	ribosome.
	B.	mitochondria.
	C.	cell membrane.
	D.	cytoplasm.
	E.	nucleus.

Normal human body cells contain how many chromosomes?

	A.	46
	B.	22
	C.	23
	D.	44
	E.	42

Hershey and Chase performed an experiment in which they used radioactive isotopes to phosphorus and sulfur to label different components of bacterial viruses. Their results clearly showed that

	A.	the viruses did not contain protein.
	B.	genetic material normally contains radioactive isotopes.
	C.	the viruses did not contain DNA.
	D.	protein was entering into the infected bacteria.
	E.	DNA was entering into the infected bacteria.

A package of histones with DNA wrapped around them forms spherical structures called

	A.	nucleosomes.
	B.	lysosomes.
	C.	ribosomes.
	D.	nucleoli.
	E.	chromatin.

DNA replication

	A.	does not require proteins.
	B.	is constantly happening in a cell.
	C.	occurs in G1 of interphase.
	D.	takes place in the nucleus of the cell.
	E.	occurs in the cytoplasm of the cell.

The two subunits of the ribosome join during

	A.	promotion of transcription.
	B.	initiation of translation.
	C.	termination of transcription.
	D.	termination of translation.
	E.	elongation.

DNA replication of a single DNA molecule is referred to as semiconservative because

	A.	each of the two DNA molecules will consist of one parental strand and one newly synthesized strand.
	B.	all the DNA strands in the two DNA molecules will have both parental and newly synthesized DNA.
	C.	it results in two nonidentical DNA molecules.
	D.	of the two DNA molecules, one is made up totally of parental DNA, while the other is entirely newly synthesized DNA.
	E.	one DNA strand is replicated continuously, while the other must be replicated discontinuously.

The bases are bonded to what part of the backbone of the DNA molecule?

	A.	the 4â carbon atom of the sugar molecule.
	B.	the 3â carbon atom of the sugar molecule.
	C.	the 5â carbon atom of the sugar molecule.
	D.	the 1â carbon atom of the sugar molecule.
	E.	the 2â carbon atom of the sugar molecule.

1
Which of the following is a component of the HIV virus ?
A
DNA
B
Capsid
C
Nucleus
D
CD4 receptor
Answered
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2
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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.
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3
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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
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4
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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
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5
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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
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6
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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.
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7
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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.
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8
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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.
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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
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10
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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

BIOL 1107 Chapter Notes - Chapter 15: Gamete, Dna Ligase, Okazaki Fragments

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