BIOLOGY 1A03 Lecture Notes - Lecture 12: Rna Interference, Small Interfering Rna, Reverse Transcriptase

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7 Mar 2018

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BIOLOGY 1A03 Full Course Notes

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Theme 3 module 4: turning off the signal. The expression of genes is regulated so that their products are presenting the right amounts at the right times. Gene expression can be regulated at: transcription initiation, rna processing, stability of rna, protein synthesis, protein modification and transport, protein degradation. It is possible to identify which embryonic cells or tissues express the gene of interest by undertaking an analysis as to where the corresponding mrna that is transcribed from that gene can be found during development in the organism. The mrna can be detected with a complementary probe that has a fluorescent tag attached to it. The complementary probe would be a short, single stranded segment of dna or rna that would bind to the mrna in a complementary fashion. This is the process of in situ hybridization. Good for a few genes of interest. Microarray techniques made it possible to examine the expression of thousands of genes at once.

Related Questions

Hello could you help me with the following questions.

1. Which strategy for testing gene function requires that you know more about the gene or pathway you are studying before you start?

a. Forward genetics

b. Reverse genetics

2. Can the Cre-loxP system be used to "knock out" a gene in a wildtype (not genetically modified) mouse?

a. Yes, the Cre recombinase can use any loxP sites, even those that have not been engineered into the genome.

b. No, the Cre-loxP system requires loxP sites to be inserted into the genome by researchers.

3. What is the mechanistic reason that in situ hybridization images are purple?

a. Binding of RNA to a probe results in a purple precipitate.

b. An antibody conjugated to alkaline phosphatase cleaves NBT/BCIP into a purple product.

c. NBT/BCIP in solution is purple.

d. Digoxigenin-labeled nucleotides in the probe react with NBT/BCIP to form a purple product.

4. In situ hybridization detects:

a. RNA

b. Both RNA and protein

c. protein

d. DNA

5. Which is NOT a mechanism for control of mRNA expression by cytoplasmic localization?

a. Localized protection

b. Nuclear export and splicing

c. Active transport along the cytoskeleton

d. Diffusion and local trapping or anchoring

#1 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?

A) Using an RNA probe complementary to the region not removed by the truncation

B) Using an RNA probe complementary to the region removed by the truncation.

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

D) Using an DNA probe complementary to the region removed by the truncation

E) Using an antibody complementary to the region not removed by the truncation.

F) Using an antibody complementary to the region removed by the truncation.

#2To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?

A) As both are composed of nucleic acids, using either would result in identical results.

B) An RNA probe because RNA has uracil bases.

C) A DNA probe because it is more stable than RNA.

D) A DNA probe because RNA cannot bind to DNA.

#3Which of the following will lower the Tm of a given DNA strand?

A)Increasing the percentage of GC base pairs

B) Raising the pH of the solution from extremely acidic to neutral

C) Decreasing the buffer concentration from 50mM NaCl to 5mM NaCl.

#4 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?

A) No, because the RNA genome would not enter the bacteria upon infection

B) No, because while DNA and RNA nucleotides are similar, they are not identical

C) Yes, because DNA and RNA nucleotides are similar

D) Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly.

#5 Griffith and Avery's transformation experiments allowed us to identify that DNA is our genetic information. Which of the following scenarios would result in bacterial cells that are capable of killing mice upon injection?

A) Heat killed non-virulent bacteria is added to a live virulent bacteria strain

B) Heat killed virulent bacteria is added to a heat killed non-virulent bacteria strain.

C) Heat killed mouse cells are added to a non-virulent bacteria.

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

A) Random DNA mutations generally won't affect RNA and protein function

B) It is faster to duplicate the genome when these are present.

C) The existence of introns can lead to multiple variations of proteins encoded by a single gene.

D) It is unlikely transposons would exist in the genome if there was too much protein coding DNA.

harlequineel21

Question 1

1 pts

Cystic fibrosis is caused by nonsense and missense mutations in the CFTR gene, which encodes for a chloride channel. You are studying cystic fibrosis patients to determine what mutation they possess in the CFTR gene. The difference between the mutant and wild type CFTR genes can be uncovered by examining the CFTR:

	DNA
	mRNA
	protein
	tRNA

Question 2

1 pts

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.

Question 3

1 pts

You would like to ensure that this experiment (to determine whether patients have a specific CFTR gene truncation using hybridization) is properly controlled. Which of the following samples must you test?

	The genomic DNA of a healthy individual who does not have cystic fibrosis.
	The genome of a CFTR patient known to have the specific truncation you are trying to identify.
	The genome of a CFTR patient with a missense mutation but full length gene.
	The genome of a healthy individual married to a CFTR patient with the specific truncation you are trying to identify.
	The genome of a patient with muscular dystrophy, which can be due to a trucation in the dystrophin gene.

Question 4

1 pts

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.

Question 5

1 pts

Which of the following will lower the Tm of a given DNA strand?

	Increasing the percentage of GC base pairs.
	Raising the pH of the solution from neutral to basic.
	Decreasing the buffer concentration from 50mM NaCl to 5mM NaCl.
	None of the above.

Question 6

1 pts

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.

Question 7

1 pts

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.

Question 8

1 pts

Griffith and Avery's transformation experiments allowed us to identify that DNA is our genetic information. Which of the following scenarios would result in bacterial cells that are capable of killing mice upon injection?

	Heat killed non-virulent bacteria is added to a live virulent bacteria strain.
	Heat killed virulent bacteria is added to a heat killed non-virulent bacteria strain.
	A heat killed virulent bacteria that is treated with a nuclease, is then added to a non-virulent bacteria strain.
	Heat killed mouse cells are added to a non-virulent bacteria.

Question 9

1 pts

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.

Question 10

1 pts

Andrew Murray's sister, Andrea, is adding to her brother's work on chromosomes. She is using cells that are unable to synthesize adenine (âade) and histidine (âhis). The plasmid she is currently working with consists of an origin of replication and the Ade gene.

Following her transformation of the plasmid into her yeast, what media will the cells be plated on to select for cells that have picked up the plasmid?

	Media containing histidine
	Media containing adenine
	Media lacking adenine
	Media lacking histidine

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BIOLOGY 1A03 Lecture Notes - Lecture 12: Rna Interference, Small Interfering Rna, Reverse Transcriptase

BIOLOGY 1A03 Full Course Notes

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