Nucleotides and Nucleic Acids

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Questions

Question 1

What are the three characteristic components of a nucleotide?

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Question 2

What is a molecule without a phosphate group, consisting of a nitrogenous base and a pentose, called?

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Question 3

In pyrimidines and purines, how are the carbon and nitrogen atoms conventionally numbered?

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Question 4

What is the key difference that defines a nucleic acid as DNA versus RNA?

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Question 5

How are successive nucleotides in both DNA and RNA covalently linked?

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Question 6

According to the Watson-Crick model, how many base pairs are there per helical turn in B-form DNA in aqueous solution?

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Question 7

What are the two primary forces that hold the DNA double helix together?

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Question 8

What is the structural characteristic of A-form DNA compared to B-form DNA?

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Question 9

What is a common feature of DNA sequences that can form hairpin or cruciform structures?

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Question 10

What is the term for the phenomenon where the absorption of UV light by a double-stranded nucleic acid increases upon denaturation?

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Question 11

What is the most important source of mutagenic alterations in DNA under normal physiological conditions?

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Question 12

What is the primary role of ATP in cellular metabolism?

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Question 13

Which of the following is NOT a major purine or pyrimidine base found in DNA and RNA?

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Question 14

What is the molar extinction coefficient at 260 nm for GMP at pH 7.0?

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Question 15

What is the term for a short nucleic acid polymer containing 50 or fewer nucleotides?

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Question 16

The chemical synthesis of DNA via the phosphoramidite method proceeds in which direction?

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Question 17

What is the consequence of the slow deamination of cytosine to uracil in DNA?

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Question 18

Which of the following enzymes uses S-adenosylmethionine as a methyl group donor for DNA methylation?

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Question 19

What is the approximate distance between vertically stacked bases inside the B-form DNA double helix?

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Question 20

Which of the following is a regulatory nucleotide that is produced in bacteria in response to amino acid starvation?

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Question 21

What is the consequence of forming a cyclobutane pyrimidine dimer in a DNA strand, as induced by UV light?

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Question 22

Which enzyme is responsible for linking a DNA fragment to a cloning vector?

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Question 23

In the Sanger dideoxy sequencing method, what is the role of a dideoxynucleoside triphosphate (ddNTP)?

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Question 24

Which of the following enzyme cofactors contains an adenosine moiety but does not participate directly in the cofactor's primary function?

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Question 25

What is the structural basis for Chargaff's rule that in any cellular DNA, the number of adenosine residues equals the number of thymidine residues (A = T)?

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Question 26

What type of RNA serves as an adapter molecule that translates the information in mRNA into a specific sequence of amino acids?

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Question 27

Which of the following is the most common form of DNA found under physiological conditions?

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Question 28

In a sample of DNA from an unknown bacterium, adenine makes up 32 percent of the total bases. What is the percentage of guanine?

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Question 29

What is the primary role of the enzyme reverse transcriptase in biotechnology applications like RT-PCR?

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Question 30

In Z-form DNA, what conformation do the purine residues typically adopt?

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Question 31

Why are the carbon numbers of the pentose ring in a nucleotide given a prime (') designation?

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Question 32

What is the typical result of RNA hydrolysis under alkaline conditions?

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Question 33

What type of damage does ionizing radiation such as x-rays and gamma rays typically cause to DNA?

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Question 34

What is the biological function of the Dam methylase in E. coli?

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Question 35

Which of the following is NOT a component of coenzyme A (CoA)?

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Question 36

What type of chemical bond links the base to the pentose in a nucleotide?

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Question 37

What are the common pyrimidine bases found in RNA?

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Question 38

The G tetraplex structure is formed most readily by DNA sequences with a very high proportion of which residue?

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Question 39

What is the effect of base-stacking interactions on the stability of the DNA double helix?

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Question 40

Which chemical agent is commonly used to cause selective removal of purine bases from DNA, resulting in an apurinic acid?

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Question 41

What is the primary function of messenger RNA (mRNA)?

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Question 42

What does a melting point (tm) of a DNA molecule, determined under fixed pH and ionic strength, allow one to estimate?

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Question 43

How many hydrogen bonds are formed between a guanine (G) and cytosine (C) base pair?

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Question 44

What is the typical conformation of a paired, double-stranded RNA helix?

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Question 45

In DNA, the two polynucleotide chains are oriented in which direction relative to each other?

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Question 46

What type of damage is typically caused by exposing DNA to near-UV radiation?

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Question 47

In the Sanger sequencing method, fragments are separated by electrophoresis based on what property?

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Question 48

What is the role of a primer in the DNA sequencing reaction catalyzed by DNA polymerase?

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Question 49

What is the primary characteristic of the backbone of both DNA and RNA?

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Question 50

What are the structural units of DNA called when they are in their free form, such as dAMP?

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