BIO282 Lecture Notes - Lecture 3: Rna Virus, Dna Virus, Uracil

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20 Jun 2018

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Differences between DNA and RNA

• DNA contains deoxy-ribose sugar instead of ribose that is in RNA

• The nucleotide base uracil is present in RNA but not in DNA while thymine is present in

DNA but not in RNA.

• Generally (not always i.e. viruses) DNA is double stranded while RNA is single stranded.

Cytosine can mutate and become Uracil. Uracil is not part of DNA. Thymine is safer as it doesn’t

mutate.

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Components of Nucleic Acids

Nitrogenous bases

2 rings - purines (AG)

1 ring - pyrimidine (pyramid has one point) (C,T,U)

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DNA is a chain of nucleotides. The nucleotides are the components of the DNA.

A nucleotide is made of 3 components:

• a deoxy-ribose sugar

• a base and

• a phosphate

A base could be A, T, G or C.

A base is attached to a sugar molecule in a nucleoside. When phosphates are attached at

the 5` carbon of the sugar in a nucleoside, it is then called a nucleotide.

Remember the following names:

Nucleoside = Sugar + base

Nucleotide = Nucleoside + phosphate (mono, di or tri for 1, 2 or 3 phosphates,

respectively)

Nucleoside monophosphate (dNMP) it has one phosphate.

Nucleoside diphosphate (dNDP) it has two phosphates.

Nucleoside triphosphate (dNTP) it has 3 phosphates.

NOTE: This is not the same as the ATP used in energy production. This has a small case “d”

in front of it. Put the small d in front because it has deoxyribose in it.

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Related Questions

QUESTION 1. Compared to eukaryotic genomes, only prokaryotic genomes:

A. contain DNA organized by histones.

B. contain usually one, circular chromosome.

C. contain plasmid DNA.

D. have chromosomes contained in a nucleus.

QUESTION 2. Azathioprine is a drug that may be prescribed to transplant recipients to reduce the chance of tissue rejection reactions. In its active state, it acts as a purine analogue, inhibiting DNA biosynthesis. This means that 6-mercaptopurine will be inserted in place of a purine containing nucleotides during DNA replication. Given this drug's mode of action, you would expect it to be incorporated into DNA in place of:

A. nucleotides containing guanine or cytosine.

B. nucleotides containing adenine or thymine.

C nucleotides containing adenine or guanine.

D. nucleotides containing guanine nucleotide or uracil.

QUESTION 3. RNA is distinguished from DNA because only RNA:

A. typically exists as a single-stranded molecule.

B. has a 3' to 5' directionality.

C. is composed of nucleotides that contain the sugar deoxyribose.

D. is composed of nucleotides that contain the nitrogen bases T, C, G, and A.

QUESTION 4. How are RNA nucleotides different from DNA nucleotides? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

A. RNA nucleotides do not contain thymine.

B. RNA nucleotides use the sugar ribose, while DNA nucleotides do not.

C. RNA nucleotides lack phosphate.

D. RNA nucleotides incorporate pyrimidine nitrogen bases, while DNA nucleotides only incorporate purine nitrogen bases.

1.Which of the following is not true about DNA? a) it is found both in the nucleus and the cytoplasm b)it is double stranded and the standards are connected by hydrogen bonds between the base pairs c) A purine base always pairs with a pyrimidine base to make up the DNA code d) it is the control center for both cell activity and heredity 2.Which of the following represents accurate base pairing in DNA ?a) Adenine to Adenine b)Adenine to Uracil c)Thymine to Cytosine d)Adenine to Thymine 3. Purines and Pyrimidines are found a) DNA only b)RNA only c) A and B d)In proteins 4.The bond that forms between carbohydrates is called a)peptide bond b) ester bond c) glycoside bond d)never ending bone 5. Which of the following does not dissolve readily in water? a)proteins b) amono acids c) steroids d) carbohydrates 6. The following arrangement of amino acids represents what level of structure ? ABACABDD a)Primary b)Secondary c)Tertiary d)Quaternary

cerisedog238

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

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BIO282 Lecture Notes - Lecture 3: Rna Virus, Dna Virus, Uracil

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