Deck 26: The Chemistry of the Nucleic Acids

Question 1

Identify the nucleoside shown below.

Answer 1

2'-deoxyadenosine

Question 2

Which of the following bases distinguish DNA from RNA?

A)adenine and cytosine
B)guanine and uracil
C)thymine and uracil
D)uracil and guanine
E)adenine and thymine

Answer 2

thymine and uracil

Question 3

What are the four common ribonucleosides?

Answer 3

cytidine,uridine,adenosine,and guanosine

Question 4

Which of the following statements concerning DNA,RNA,and their components is (are)not correct?

A)Phosphoric acid has three dissociable OH groups which can also react with alcohols to form phosphoesters.
B)Across the DNA helix,purine bases hydrogen bond only to other purine bases.
C)The two substituted pyrimidines in DNA are cytosine and thymine.
D)both B and C
E)none of the above

Question 5

Show that you understand how the structural components of DNA are bonded together by drawing a linear segment that contains 3 base residues.

Question 6

Name the two pyrimidine bases which serve as components in deoxyribonucleotides.

Question 7

Which of the following are known as pyrimidines?

A)cytosine and thymine
B)adenine and cytosine
C)adenine and thymine
D)guanine and thymine
E)adenine and guanine

Question 8

Draw the structure of guanosine.

Question 9

What is the major structural difference between a ribonucleoside and a ribonucleotide?

Question 10

What is a nucleoside? Give an example.

Question 11

Draw the structure of 2'-deoxycytidine 3'-monophosphate.

Question 12

Name the two purine bases which serve as components in ribonucleosides.

Question 13

Identify the nucleoside shown below.

A)adenosine
B)guanosine
C)cytidine
D)uridine
E)thymidine

Question 14

What is a nucleotide? Give an example.

Question 15

When phosphoric acid is heated it loses water to form an anhydride known as pyrophosphate or pyrophosphoric acid.What is the structure of pyrophosphoric acid?

A)
B)
C)
D)
E)

Question 16

Which of the following is the proper name of the nucleoside made from adenine and found in DNA?

A)adenosine
B)2'-deoxyadenosine
C)2-deoxyadenosine
D)2'-oxyadenosine
E)2'-deoxyadenine

Question 17

Draw the structure of AMP.

Question 18

Draw the structure of UDP.

Question 19

Identify the nucleoside shown below.

Question 20

Besides a possible difference in base structure,what is the major structural difference between ribo- and deoxyribonucleosides?

Question 21

Which of the following phosphate groups is found in nucleic acids?

A)
B)
C)
D)
E)

Question 22

How many hydrogen bonds exist between the cytosine/guanine base pairs?

A)1
B)2
C)3
D)4
E)5

Question 23

Propose a mechanism for the formation of cyclic AMP from ATP.

Question 24

Draw the structure of cytidine 5'-phosphate.

Question 25

Draw the structure of ATP.

Question 26

Identify the sugar and the base in the structure below.

Question 27

Which of the following constitutes the primary structure of a nucleic acid?

A)the sequence of the bases in the strand
B)the sequence of the riboses in the strand
C)the sequence of the deoxyriboses in the strand
D)the sequence of the phosphodiesters in the strand
E)the sequence of the 5'-OH groups in the strand

Question 28

Which of the following statements is not true about the structure of DNA as proposed by Watson and Crick?

A)The number of adenines in DNA is equal to the number of thymines.
B)The number of cytosines is equal to the number of guanines.
C)DNA consists of two strands of nucleic acids with the sugar-phosphate backbone on the inside and the bases on the outside.
D)The chains in DNA are held together by hydrogen bonding.
E)Adenine always pairs with thymine and guanine always pairs with cytosine.

Question 29

Identify the structure.

A)uracil
B)cytosine
C)guanine
D)thymine
E)adenine

Question 30

Draw the structure of thymidine.

Question 31

Identify the sugar and the base in the structure below.

Question 32

Draw the structure of UMP.

Question 33

A commonly known nucleotide is adenosine 3',5'-phosphate (cAMP).What is the structure of cAMP?

Question 34

Identify the structure.

A)uracil
B)cytosine
C)guanine
D)thymine
E)adenine

Question 35

Draw the structure of TTP.

Question 36

Draw the structure of dTTP.

Question 37

Which of the following reaction sequences best describes the formation of the nucleic acid in the biosynthesis of DNA?

A)nucleophilic attack of a 5'-OH group of one nucleotide on the β-phosphorus of another
B)nucleophilic attack of a 5'-OH group of one nucleotide on the α-phosphorus of another
C)nucleophilic attack of a 3'-OH group of a nucleotide on the γ-phosphorus of another
D)nucleophilic attack of a 3'-OH group of one nucleotide on the β-phosphorus of another
E)nucleophilic attack of a 3'-OH group of one nucleotide on the α-phosphorus of another

Question 38

Draw the structure of ADP.

Question 39

Draw the structure of uridine.

Question 40

Name the compound.

Question 41

List the number of pairs of chromosomes in a human.

A)18 pairs of chromosomes
B)20 pairs of chromosomes
C)23 pairs of chromosomes
D)25 pairs of chromosomes
E)27 pairs of chromosomes

Question 42

How many billion base pairs are there in the total DNA of a human cell?

A)3
B)5
C)8
D)11
E)13

Question 43

What is meant by semiconservative DNA replication?

Question 44

Which of the following statements best describes the meaning of transcription?

A)It is the synthesis of rRNA from a DNA blueprint.
B)It is synonymous with replication.
C)It is the synthesis of identical copies from a DNA blueprint.
D)It is the synthesis of mRNA from a DNA blueprint.
E)It is the synthesis of tRNA from a DNA blueprint.

Question 45

In which of the following helical forms does DNA in living organisms mainly exist?

A)Z-helix
B)a-helix
C)b-helix
D)B and C
E)A,B and C

Question 46

What is the sequence of bases in the strand of DNA that is complementary to that shown below? 5'-T-T-C-A-C-T-G-A-C-3'

A)5'-T-T-C-A-C-T-G-A-C-3'
B)3'-T-T-C-A-C-T-G-A-C-5'
C)5'-A-A-G-T-G-A-C-T-G-3'
D)5'-G-T-C-A-G-T-G-A-A-3'
E)3'-U-U-C-A-C-U-G-A-C-5'

Question 47

Assuming that the human genome with its 3 billion base pairs is entirely in a b-helix,how long is the DNA in a human cell?

Question 48

Show the hydrogen bonding which occurs when guanine and cytosine form a base pair.

Question 49

Describe how RNA is easily cleaved.

Question 50

Which of the following is the conventional method of writing the base sequence of a portion of a DNA chain?

A)5'-end--bases--5'-end
B)5'-end--bases--3'-end
C)3'-end--bases--5'-end
D)3'-end--bases--3'-end
E)5'-end--bases--2'-end

Question 51

Identify the type(s)of base pairing present in DNA.You may choose more than one answer.

A)adenine and thymine
B)cytosine and guanine
C)cytosine and thymine
D)adenine and uracil
E)thymine and adenine

Question 52

Show the hydrogen bonding which occurs when adenine and thymine form a base pair.

Question 53

Which of the following statements concerning nucleic acids is not correct?

A)The enzymes that catalyze DNA synthesis are known as DNA polymerases.
B)The growing DNA polymer is synthesized in the 5' to 3' direction.
C)RNA strands are synthesized in the 3' to 5' direction.
D)In DNA the distance between the strands of the double helix is relatively constant.
E)Unlike DNA,RNA is easily cleaved because the 2'-OH group of the ribose can act as the nucleophile that cleaves the strand.

Question 54

Which of the following statements is not true about RNA?

A)It is single stranded.
B)It is smaller than DNA.
C)It has fewer base pairs than DNA.
D)It exists exclusively in the nucleus of the cell.
E)There are three kinds: rRNA,mRNA,and tRNA.

Question 55

Why is RNA more easily cleaved than DNA?

Question 56

What are stacking interactions in DNA and what purpose do they serve?

Question 57

Give the order for base pairing for the following strand. G-C-A-T-T-C-C-G-A-T

A)C-G-U-A-A-G-G-C-U-A
B)U-G-T-A-A-G-G-U-T-U
C)A-T-G-C-C-T-T-A-G-C
D)T-A-C-G-G-A-A-T-C-G
E)C-G-T-A-A-G-G-C-T-A

Question 58

The human genome contains approximately how many base pairs?

A)300
B)300,000
C)3 × 10⁹
D)3 × 10¹⁵
E)3 × 10²³

Question 59

Identify the bonding in DNA between the nucleotides.

A)5' to 4'
B)5' to 3'
C)3' to 5'
D)4' to 3'
E)3' to 4'

Question 60

In an entire DNA strand,what percentage consists of genetic information and what percentage consists of introns?

A)98% genetic information,2% introns
B)2% genetic information,98% introns
C)50% genetic information,50% introns
D)100% genetic information,0% introns
E)99% genetic information,1% introns

Question 61

Which of the following statements explains what nucleic acids are?

A)They are acidic in nature.
B)They are the carriers of genetic information.
C)DNA and RNA are collectively known as nucleic acids.
D)Nucleic acids are chains of five-membered ring sugars,each bonded to a heterocyclic amine,linked by phosphate groups.
E)all of the above

Question 62

For what compound is ATP an abbreviation?

A)adenine triphosphate
B)adenosine tetraphosphate
C)adenine tetraphosphate
D)adenosine triphosphate
E)adenine triphosphoric acid

Question 63

What are Maxam-Gilbert and Sanger sequencing?

Question 64

What is the composition of a ribosome?

A)40% protein,60% rRNA
B)60% protein,40% tRNA
C)40% protein,60% tRNA
D)40% protein,60% mRNA
E)100% protein,0% rRNA

Question 65

Which of the following explains the kinetic stability of ATP?

A)The hydrolysis of ATP occurs rapidly in the absence of a catalyst because the phosphate bonds are thermodynamically labile.
B)ATP is positively charged at physiological pH.
C)Water,the major component of cytoplasm,is a strong and very reactive nucleophile.
D)ATP is negatively charged at physiological pH and thus repels the approach of nucleophiles.
E)none of the above

Question 66

Which of the following metal ions complexes with cellular ATP to neutralize some of its negative charges at the active site of an enzyme in order that nucleophilic substitution reactions proceed rapidly?

A)manganese
B)iron
C)cobalt
D)magnesium
E)calcium

Question 67

Which of the following is not true about retroviruses?

A)The genetic information is contained in RNA.
B)The genetic information flows from DNA to RNA.
C)Drugs have been designed to interfere with the synthesis of DNA by retroviruses.
D)AZT is a design drug that was synthesized to combat the HIV retrovirus.
E)The retrovirus uses the sequence of bases in RNA as a template to synthesize DNA which enters and infects the host cell.

Question 68

All tRNAs have ________ at the 3'-end.

A)CCA
B)UUC
C)GCC
D)CAG
E)GGA

Question 69

Give the final product of an amino acid reacting with ATP,then t-RNA.

Question 70

Which of the following base sequences would most likely be recognized by a restriction endonuclease?

A)ACGCGT
B)ACGGGT
C)ACACGT
D)ACATCGT
E)CCAACC

Question 71

Methionine is the first amino acid incorporated into the heptapeptide specified by the following mRNA:
5'-AUGGACCCCGUUAUUAAACAC-3'.
What is the sequence of the amino acid in the heptapeptide?

Question 72

Give the second step of PCR.

A)esterification
B)strand separation
C)base-pairing of the primers
D)DNA synthesis
E)hydrolysis

Question 73

Which of the following is true about tRNA?

A)All tRNAs have a CCG sequence at the 3'-end.
B)All tRNAs have a CCG sequence at the 5'-end.
C)All tRNAs have a CCA sequence at the 5'-end.
D)All tRNAs have a CCA sequence at the 3'-end.
E)All tRNAs have a CAC sequence at the 3'-end.

Question 74

Which of the following reactions converts nucleotide subunits into nucleic acids?

A)nucleophilic attack on the α-phosphorus of ATP
B)nucleophilic attack on the β-phosphorus of ATP
C)nucleophilic attack on the γ-phosphorus of ATP
D)A and B
E)A,B,and C

Question 75

What is a codon? Give an example.

Question 76

Give the first step of PCR.

A)esterification
B)strand separation
C)base-pairing of the primers
D)DNA synthesis
E)hydrolysis

Question 77

Which of the following statements best explains the source of energy behind the ATP molecule?

A)the energy released when a phosphoanhydride bond of ATP is broken
B)the energy released when adenosine binds to the phosphate
C)the energy released when ribose binds to the phosphate
D)the energy released when adenine binds to ribose
E)the energy released when ATP is reduced

Question 78

What is the most favored reaction when an amino acid and ATP react together?

A)nucleophilic attack on a-phosphorus
B)nucleophilic attack on b-phosphorus
C)nucleophilic attack on g-phosphorus
D)nucleophilic attack on the NH₂ of adenosine
E)nucleophilic attack on the aromatic nitrogen of adenosine

Question 79

Which of the following is the first step in the mechanism of the reaction shown below?

A)Carboxylate ion attacks the thiol.
B)Carboxylate ion attacks the α-phosphorus of ATP.
C)Carboxylate ion attacks the γ-phosphorus of ATP.
D)Thiol molecule attacks the β-phosphorus of ATP.
E)Thiol molecule attacks the acyl group.

Question 80

Give the maximum number of different codons possible.

A)56
B)60
C)64
D)70
E)76