BIOL 1362 Lecture Notes - Lecture 15: Semiconservative Replication, Dna Polymerase, Dna Replication

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cyanantelope236

18 Feb 2017

School

University of Houston

Department

Biology

Course

BIOL 1362

Professor

Medrano

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Document Summary

Ch 15: dna and the gene: synthesis and repair. Researchers knew that chromosomes were comprised of dna and protein. Most biologist thought genes were made of proteins because. Dna is comprised of only 4 different nucleotides. Hershey and chase studied how the t2 virus infects the bacterium e. coli. T2 infection of e. coli begins when the virus injects its genes into the cell. These genes direct production of new virus particles. The virus"s protein coat ( capsid ) is left behind on the outside of the cell. Only the genes of a virus enter a host cell. Hershey and chase grew the virus in the presence of one of 2 radioactive isotopes. Labeled viruses were used to infect e. coli cells. Result: only the radioactive dna was found inside the cells. A backbone made up of the sugar and phosphate groups of deoxyribonucleotides. A series of nitrogen containing bases that project from the backbone.

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

Multiple answers to each question might be possible!

You decide to identify the CFTR mutation by analyzing the genomic DNA of your patients compared to healthy individuals. You specifically are looking to see whether a specific 3' gene truncation has occurred in the patients. You will determine this using hybridization techniques with samples from healthy and CF patients. Which of the following will allow you to accomplish this?

	Using an RNA probe complementary to the region not removed by the truncation.
	Using an RNA probe complementary to the region removed by the truncation.
	Using an DNA probe complementary to the region not removed by the truncation.
	Using an DNA probe complementary to the region removed by the truncation.

To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?

	As both are composed of nucleic acids, using either would result in identical results.
	An RNA probe because RNA has uracil bases.
	An RNA probe because it could also be used in a translation experiment.
	A DNA probe because it is more stable than RNA.
	A DNA probe because RNA cannot bind to DNA.

One step of the Hershey/Chase experiment involved blending the virus/cell mixture before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?

	To collect the bacteria at the bottom of the tube.
	To break open the bacteria to release the genome.
	To separate the bacteria from the bacteriophages.
	To be able to detect the radioactivity.

Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?

	No, because only DNA can be labeled with radioactivity.
	No, because the RNA genome would not enter the bacteria upon infection.
	No, because while DNA and RNA nucleotides are similar, they are not identical.
	Yes, because DNA and RNA nucleotides are similar.
	Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly.

The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?

	Random DNA mutations generally won't affect RNA and protein function.
	It is faster to duplicate the genome when these are present.
	The existence of introns can lead to multiple variations of proteins encoded by a single gene.
	It is unlikely transposons would exist in the genome if there was too much protein coding DNA.

Explain the 5â to 3â directionality of a DNA stand.

	It is due to the fact that the free 5â carbon is on one end and the free 3â carbon is on the other
	It is due to the fact that new nucleotide are added to the 5â carbon of the previous nucleotide
	It is due to the fact that there are 3 phosphate groups attached to the 5â carbon
	It is due to the fact the complementary strand is 3â to 5â
	More than one of the above explain the 5â to 3â directionality

You accidentally add a mutant dNTP (which has an H instead of an OH connected to the 3â carbon) to a reaction where DNA is being replicated. Which of the following is true of this mutant dNTP?

	It can be incorporated into DNA strand but cannot form a phosphodiester bond with an incoming wild type dNTP
	It can be incorporated into a DNA strand but cannot base pair with a complementary nucleotide
	It can be incorporated into a DNA strand and can form a phosphodiester bond with an incoming dNTP, but only if it is another mutant dNTP
	It cannot be incorporated into a DNA strand.

Why does DNA polymerase utilize an RNA primer?

	DNA polymerase is unable to initiate strand synthesis but RNA polymerase can
	DNA polymerase can only add a dNTP to an rNTP
	DNA synthesis proceeds in the 3â to 5â when initiating strand synthesis
	Chromosomal DNA contains interspersed RNA fragments
	The RNA primer increases stability of the newly synthesized strand

rosehippopotamus950

Please provide correct answer and explanation to the answer,Thank you!

If an enterprising graduate student decided to repeat theHershey-Chase

experiment but neglected to perform the blending portion, wherewill the

isotopes be found?

a. 35S will be found in the supernatant and 32P will be found inthe pellet

b. 32P will be found in the supernatant and 35S will be found inthe pellet

c. Both 32P and 35S will be found in the supernatant

d. Both 32P and 35S will be found in the pellet

e. None of the above are correct
Chargaffï¿½s rules include:

a. The ratio of Aï¿½s + Tï¿½s to Gï¿½s + Cï¿½s is always consistent

b. A=G and T=C

c. Purines/Pyrimidines = 1

d. More than one of the above are true

e. None of the above are true
Sea Urchin DNA contains 18% guanine (which is true); how muchthymine

does it contain?

a. 9%

b. 18%

c. 32%

d. 36%

e. 64%
E. coli DNA contains a little over 25% guanine. If samples weretaken of E.

coli DNA and Sea Urchin DNA and denatured in water baths, whichwould

melt at a lower temperature?

a. E. coli DNA

b. Sea Urchin DNA

c. They would melt at the same temperature

d. There is not enough information to determine the answer

e. DNA doesnï¿½t ï¿½melt,ï¿½ it isnï¿½t ice cream for goodness sake!
If testing the second generation results in tube B, which modelcan we

conclude is correct?

a. Dispersive

b. Semi-conservative

c. Conservative

d. Semi-dispersive

e. We canï¿½t conclude yet, it could still be more than onepossibility
Phosphorus is required to synthesize dNTPs used in DNAreplication. Imagine

you grow E. coli in media containing non-radioactive phosphorusfor many

generations, then switch the E. coli to media containingradioactive

phosphorous (32P). You then sample the E. coli after one roundof replication

for radioactivity. Where will you find radioactive phosphorus inthe DNA?

a. Both strands will contain 32P

b. One strand will contain 32P

c. Neither strand will contain 32P

d. Drats! I knew I should have done suggested problem 12.19!
Which of the following statements about chromosomes are alwaystrue?

I. Non-histone proteins make up about 5% of a eukaryotic

chromosome by weight

II. Histones have a negative charge

III. Prokaryotes have a single linear chromosome

a. Only Statement I is true

b. Only Statement II is true

c. Only Statement III is true

d. More than one of the above statements are true

e. None of the above statements are true
What portion of the human genome is made up of highly repetitiveDNA?

a. Less than 5%

b. 6 ï¿½ 20%

c. 21 ï¿½ 30%

d. 31 ï¿½ 40%

e. Over 40%
Which of the following statements are always true?

I. Histones are very conserved between species

II. Archaea have nuclei

III. Prokaryotes are haploid and eukaryotes are diploid

a. Only Statement I is true

b. Only Statement II is true

c. Only Statement III is true

d. More than one of the above statements are true

e. None of the above statements are true
An individualï¿½s phenotype is a function of:

a. The alleles they carry

b. The environment they live in

c. The interaction between an individuals genes and theenvironment

d. Two of the above are correct

e. All of the above are correct
A homologous pair of chromosomes showing a

crossover are shown to the right for reference. Are all

the sperm from one human male genetically identical?

a. Yes

b. No, variation occurs during mitosis

c. No, variation occurs during meiosis I

d. No, variation occurs during meiosis II

e. No, variation occurs during both meiosis I and II
Production of gametes in humans requires which kind ofdivision?

a. Meiotic and is reductional

b. Mitotic and is reductional

c. Meiotic and is equational

d. Mitotic and is equational

e. None of the above

scarletmallard658

BIOL 1362 Lecture Notes - Lecture 15: Semiconservative Replication, Dna Polymerase, Dna Replication

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