Deck 25: Nucleic Acids and Protein Synthesis

Question 1

Which of the following is not a pyrimidine?

A)Cytosine
B)Thymine
C)Guanine
D)Uracil
E)All of these choices are pyrimidines.

Answer 1

Guanine

Question 2

What are the names of the nucleosides found in DNA?

A)2'-Deoxyadenosine,uridine,thymine,2'-deoxyguanosine,
B)2'-Deoxyadenosine,2'-deoxythymidine,2'-deoxyguanosine,2'-deoxycytidine
C)2'-Deoxyadenoside,2'-deoxythymidine,2'-deoxyguanoside,2'-deoxycytidine
D)Adenosine,uridine,guanosine,cytidine
E)2'-Deoxyadenoside,thymidine,2'-deoxyguanoside,2'-deoxycytidine

Answer 2

2'-Deoxyadenosine,2'-deoxythymidine,2'-deoxyguanosine,2'-deoxycytidine

Question 3

What are the names of the nucleosides found in RNA?

A)Adenosine,uracil,thymine,guanoside
B)2'-Deoxyadenosine,2'-deoxythymidine,2'-deoxyguanosine,2'-deoxycytidine
C)Adenosine,thymidine,guanosine,cytidine
D)Adenosine,uridine,guanosine,cytidine
E)Adenine,uracil,guanoside and cytosine

Answer 3

Adenosine,uridine,guanosine,cytidine

Question 4

A purine:

A)contains four nitrogens in the ring system.
B)is bicyclic.
C)can participate in hydrogen bonding.
D)is a heterocyclic base.
E)All of these choices.

Question 5

The hydrogen bonding for the base pairs of DNA is between:

A)amide carbonyl and -NH_2.
B)amide N-H and cyclic amine nitrogens.
C)alcohols and carbonyls.
D)All of these choices.
E)Only two of these choices.

Question 6

The primary function of nucleic acids is:

A)the catalysis of biochemical reactions.
B)the regulation of reactions that occur in the body.
C)the preservation,transcription and translation of information.
D)the acid-catalyzed hydrolysis of nucleotides.
E)the neutralization of nucleic bases.

Question 7

The monomeric units of nucleic acids are which of these?

A)d-Ribose or 2-deoxy-d-ribose
B)Phosphate ions
C)Purines
D)Nucleosides
E)Nucleotides

Question 8

The carbohydrates that form part of nucleosides in RNA and DNA,respectively,are:

A)d-ribose and 2-deoxy-l-ribose
B)d-ribose and 2-deoxy-d-ribose
C)l-ribose and 2-deoxy-l-ribose
D)2-deoxy-d-ribose and d-ribose
E)2-deoxy-l-ribose and d-ribose

Question 9

An RNA nucleoside will undergo hydrolysis in dilute acid to yield which of the following?

A)2-Deoxy-d-ribose and a heterocyclic base
B)2-Deoxy-d-ribose,a heterocyclic base,and phosphate ion
C)d-Ribose and a heterocyclic base
D)d-Ribose,a heterocyclic base,and phosphate ion
E)d-Ribose and phosphate ion

Question 10

Which statement concerning the monosaccharide portion of nucleotides is true in every case?

A)The monosaccharide is in the pyranose form.
B)The linkage to phosphate is at carbon #3.
C)The heterocyclic base is attached to carbon #1 of the monosaccharide.
D)The monosaccharide-nitrogen base linkage is $\infty$ .
E)The monosaccharide is 2-deoxy-d-ribose.

Question 11

In RNA,adenine can be linked to

A)deoxyribose via $\beta$ -N-glycosidic bonds
B)uracil via hydrogen bonds
C)phosphate via phosphodiester bonds
D)guanine via amide bonds
E)All of the above

Question 12

A nucleotide unit is composed of:

A)a five carbon monosaccharide.
B)a phosphate group.
C)a heterocyclic base.
D)an amino acid.
E)More than one of these choices.

Question 13

The DNA and RNA molecules carry genetic information in cells.What is their specific function?

A)DNA is the most important molecule as it directs the synthesis of proteins by transcribing and translating the information from RNA.
B)DNA translates the information for protein synthesis; RNA archives and transcribes information from the DNA for protein synthesis.
C)DNA archives information for protein synthesis; RNA transcribes and translates information from the DNA for protein synthesis.
D)DNA and RNA are in charge of both transcribing and translating information for the synthesis of proteins from the nucleus.
E)RNA archives information for protein synthesis,transcribes and translates it with help of molecules synthesized from DNA.

Question 14

Each section of DNA that codes for a given protein is called:

A)Proteome
B)Gene
C)Allele
D)Genome
E)Metabolome

Question 15

In a nucleotide unit,the components are sequentially linked:

A)monosaccharide-phosphate-heterocyclic base.
B)amino acid-monosaccharide-phosphate.
C)phosphate-monosaccharide-heterocyclic base.
D)monosaccharide-amino acid-phosphate.
E)heterocyclic base-phosphate-monosaccharide.

Question 16

Which are the products of hydrolysis of a certain RNA nucleotide?

A)d-Ribose,adenine
B)d-Ribose,guanine,phosphate
C)d-Ribose,thymine,phosphate
D)2-Deoxy-d-ribose,cytosine,phosphate
E)2-Deoxy-d-ribose,adenine

Question 17

Which heterocyclic base found in RNA does not occur in DNA?

A)Guanine
B)Thymine
C)Cytosine
D)Uracil
E)Adenine

Question 18

A genome is defined as:

A)the set of all genetic information coded by DNA in an organism.
B)the set of all genes present in the RNA in an organism.
C)the set of alleles coded by the DNA of an organism.
D)the gene that produces a protein in an organism.
E)the set of proteins elaborated by an organism.

Question 19

The following structure represents the less common (in DNA,at least)tautomeric form of ___.

A)Cytosine
B)Thymine
C)Adenine
D)Guanine
E)Uracil

Question 20

What are the monomeric units released upon mild degradation of a nucleotide?

A)A purine or pyrimidine base,a pentose and a phosphate ion.
B)A purine or pyrimidine base and a pentose.
C)A purine or pyrimidine,a hexose and a phosphate ion.
D)A purine or pyrimidine,a hexose and three phosphate ions.
E)A pyrimidine,a pentose and adenylic acid.

Question 21

Which is the predominant tautomeric form of guanine when it is present in DNA?

A)I
B)II
C)III
D)IV
E)V

Question 22

Supply the missing reagent in the following synthesis.

A)(CH₃)₂C=O
B)HOCH₂CH₂OH
C)CH₃CHOHCH₃
D)CH₃CCl₂CH₃
E)CH₃CHClCH₃

Question 23

Which is a correct statement concerning DNA structure?

A)The base and the phosphate units are linked by hydrogen bonds.
B)The sugar and the phosphate units are linked by phosphodiester bonds.
C)The base and the sugar units are linked by $\beta$ -N-glycosidic bonds.
D)Two of these statements are correct.
E)None of these statements are correct.

Question 24

Hydrolysis of DNA from various species gives which of the following results?

A)The mole percentage of adenine is approximately equal to that of thymine.
B)The mole percentage of cytosine is approximately equal to that of guanine.
C)The total mole percentage of purines is approximately equal to that of pyrimidines.
D)The mole percentage of adenine is approximately equal to that of cytosine.
E)More than one of these choices is correct.

Question 25

The synthesis of adenosine by the reaction shown below likely occurs by what reaction mechanism?

A)An S_N2 reaction
B)An S_NAr reaction
C)An elimination-addition reaction
D)An S_N1 reaction
E)An E₂ reaction

Question 26

Supply the missing reagent(s)in the synthesis below.

A)PO₄^3- and C₆H₅CH₂OH
B)PO₄^3- and C₆H₅CH₂Cl
C)
D)C₆H₅CH₃ + POCl₃
E)C₆H₅CH₂OH + H₃PO₄

Question 27

In DNA,adenine can be linked to ___.

A)Deoxyribose via $\beta$ -N-glycosidic bonds
B)Uracil via hydrogen bonds
C)Phosphate via phosphodiester bonds
D)Guanine via amide bonds
E)All of these choices.

Question 28

Which is an incorrect statement concerning the DNA double helix?

A)The sugar-phosphate backbone is on the inside of the helix and the base pairs are on the outside.
B)The two strands are identical but proceed in opposite directions.
C)The two strands are linked by glycosidic bonds.
D)Only purine-purine and pyrimidine-pyrimidine base pairs can be accommodated.
E)All of these statements are incorrect.

Question 29

The primary structure of DNA is given by

A)The sequence of nucleosides in the DNA strand.
B)The type of purine and pyrimidine bases along the DNA helix.
C)The sequence of nucleotides in the DNA strand.
D)The phosphate ester linkages in the DNA strand.
E)The 3'-OH of the ribose in connection to the 5'-OH of the subsequent nucleotide.

Question 30

In DNA,thymine can pair via hydrogen bonding to ___?

A)Cytosine
B)Uracil
C)Adenine
D)Guanine
E)Deoxyribose

Question 31

The base sequence of the DNA is known as:

A)Gene
B)Primary structure
C)Beta sheet structure
D)Tertiary structure
E)Secondary structure

Question 32

Which is an incorrect statement concerning DNA structure?

A)The base and the phosphate units are linked by phosphodiester bonds.
B)The sugar and the phosphate units are linked by hydrogen bonds.
C)The base and the sugar units are linked by $\beta$ -N-glycosidic bonds.
D)Two of these statements are incorrect.
E)All of these statements are incorrect.

Question 33

Acyclovir is a nucleoside that is highly effective in treating

A)leukemia in children
B)certain type of herpes viruses
C)gout
D)skin cancer
E)several type of tumors

Question 34

In DNA,cytosine can pair via hydrogen bonding to ___?

A)Deoxyribose
B)Uracil
C)Adenine
D)Guanine
E)All of these choices.

Question 35

The analytical data for DNA samples which led to generalizations such as (%G + %A) $\approx$ (%C + %T)came from the research of what individual?

A)James Watson
B)Francis Crick
C)Erwin Chargaff
D)Arthur Kornberg
E)Maurice Wilkins

Question 36

In the synthesis of cytidine (Bz protected),the amino group at position 4 (N⁴)of cytosine is protected with a benzoyl protecting group because

A)the primary amino group would react faster than the secondary N¹.
B)The cytosine reagent would not be soluble in the reaction medium.
C)Cytosine needs to be activated with the benzoyl protecting group.
D)The amino group needs to remain protected after hydrolysis of benzoyl groups.
E)The activation of the primary is needed for the reaction with the d-ribose.

Question 37

What is the secondary structure of DNA?

A)An alpha-helix
B)A pleated sheet
C)A flat sheet
D)A double helix
E)A random coil

Question 38

Complete hydrolysis of adenylic acid would yield which of these?

A)Adenosine and a phosphate ion
B)Adenine,d-ribose,and a phosphate ion
C)Adenine and d-ribose
D)Adenine and 2-deoxy-d-ribose
E)A pyrimidine,a pentose,and a phosphate ion

Question 39

Which bases pair in DNA by hydrogen bonding?

A)Cytosine and thymine
B)Cytosine and uracil
C)Adenine and guanine
D)Adenine and thymine
E)Adenine and uracil

Question 40

Which is an incorrect statement concerning the DNA double helix?

A)The sugar-phosphate backbone is on the outside of the helix and the base pairs are on the inside.
B)The two strands are identical but proceed in opposite directions.
C)Hydrogen bonding holds together the two strands.
D)Only purine-pyrimidine base pairs can be accommodated.
E)The sugar-phosphate backbone is completely regular.

Question 41

Consideration of tautomerism in guanine suggests that it can exist in lactam and lactim forms.The form that is typically found in DNA is ___,typically pairs with ___,while the other form is likely to pair with ___,leading to the possible spontaneous mutations.

A)lactam,cytosine,thymine
B)lactam,cytosine,adenine
C)lactim,cytosine,thymine
D)lactam,uracil,cytosine
E)lactim,cytosine,uracil

Question 42

What is the transfer RNA anticodon for the messenger RNA codon,G-C-A?

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

Question 43

What is a correct statement?

A)A gene contains a number of introns and exons.
B)Introns are portions of the genes that are expressed.
C)The exons are portions of the gene that are cut off during expression.
D)Introns and exons can express independent from each other.
E)Introns are spliced together after removal of exons.

Question 44

The codon is part of

A)mRNA
B)rRNA
C)tRNA
D)DNA
E)None of these choices.

Question 45

The formation of a new DNA molecule which is an exact copy of a pre-existing one is designated by what term?

A)Duplication
B)Transcription
C)Translation
D)Replication
E)Reproduction

Question 46

Which is the predominant tautomeric form of cytosine when it is present in DNA?

A)I
B)II
C)III
D)None of these choices.
E)I,II and III are present in approximately equal amounts.

Question 47

Which of these has the smallest molecular weight?

A)rRNA
B)mRNA
C)DNA
D)tRNA

Question 48

Concerning the genetic code,which of the following is an incorrect statement?

A)Not all codons specify amino acids.
B)There are a total of 64 different triplets.
C)For each amino acid there are the same number of codons.
D)The triplet codons are incorporated in messenger RNA.
E)The triplet AUG is a "start" codon.

Question 49

Where is the sequence of bases termed an "anticodon" found?

A)mRNA
B)tRNA
C)rRNA
D)DNA
E)Polysomes

Question 50

The suggested mechanism of catalysis for the peptide bond formation during protein synthesis involves

A)a guanine group that produces acid-base catalysis in the attack of the amino group of one amino acid to the carboxylic acid function of the other.
B)an acid-base catalysis effected by a glutamic acid in the RNA during the nucleophilic attack of the amino group on the acyl carbon of the peptide.
C)A tetrahedral intermediate formed by the attack of a base from the tRNA on the $\alpha$ -amino group of the incoming amino acid.
D)a total or partial removal of a proton on the $\alpha$ -amino group of an amino acid facilitating the attack on the acyl carbon of the growing peptide on the tRNA.
E)a nucleophilic attack of an adenine on the $\alpha$ -amino group of the incoming amino acid.

Question 51

Nitrous acid (HNO₂)is a suspected mutagen because of its reaction with:

A)amine groups.
B)ribose.
C)phosphates.
D)alcohols.
E)ketones.

Question 52

What statement is false?

A)mRNA migrates into the cytoplasm after the introns are removed in the nucleus.
B)The ribosomes are formed by approximately two-thirds RNA and one-third protein.
C)The 30S subunit of the ribosome carries catalytic activity for translation.
D)The 30S and 50S subunits are components of the ribosomal RNA.
E)The 50S subunit joins one amino acid to the next by an amide bond.

Question 53

During translation,the segment on the mRNA that corresponds to the base sequence C-G-A along a gene segment of DNA,would bind to the anticodon ___ on a tRNA.

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

Question 54

The anticodon is part of

A)mRNA
B)tRNA
C)rRNA
D)DNA
E)None of these choices.

Question 55

The action of nitrous acid (HNO₂)on 5-methylcytosine produces which nitrogen base?

A)Adenine
B)Guanine
C)Cytosine
D)Thymine
E)Uracil

Question 56

Consider the effect of nitrous acid on the adenine residue of a DNA strand.The product now resembles ___,and is likely to pair with ___,instead of with ___,leading to the possible mutations.

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

Question 57

In DNA,the lactim form of guanine will pair with which base?

A)Cytosine
B)Adenine
C)Uracil
D)Thymine
E)No pairing is possible.

Question 58

If an mRNA codon is GUC,what was the original base sequence in DNA?

A)GUC
B)GTC
C)CAG
D)GAC
E)CTG

Question 59

Which is the messenger codon which calls for the initiation of protein synthesis?

A)AUG
B)GUA
C)UAG
D)AUC
E)CAC

Question 60

Which is the predominant tautomeric form of adenine when it is present in DNA?

A)I
B)II
C)III
D)IV
E)V

Question 61

What is the order of the three main synthetic steps used for the laboratory synthesis of oligonucleotides?

A)Demethylation,coupling,hydrolysis
B)Protecting group removal,coupling,oxidation
C)Coupling,activation,detritylation
D)Detritylation of monomer,activation,coupling,oxidation,hydrolysis
E)Coupling,oxidation,detritylation

Question 62

The codon consists of a sequence of three

A)bases
B)amino acids
C)three purines
D)pyrimidines
E)lipids

Question 63

Specific amino acids attach to the arm of a tRNA that ends in ___,via a(n)___ bond.

A)CCG,ester
B)ACG,ether
C)CCA,glycosidic
D)ACA,amide
E)CCA,ester

Question 64

If the base sequence along a segment of DNA were G-C-C-A-T,what would be the base sequence of messenger RNA synthesized from this sequence?

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

Question 65

If you start a PCR amplification with one molecule of double stranded DNA,how many double stranded copies will you obtain after 10 cycles?

A)2
B)8
C)20
D)1024
E)512

Question 66

Relatively short synthetic strands of DNA complementary to certain portions of a gene are known as:

A)antisense oligonucleotides.
B)templates.
C)palindromes.
D)endonucleases.
E)polymerases.

Question 67

If the base sequence along a segment of DNA were G-C-C-A-T,what would be the base sequence of messenger RNA synthesized from this sequence?

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

Question 68

During the laboratory synthesis of oligonucleotides

A)A phosphite triester is oxidized to a phosphate triester with iodine.
B)A phosphate triester is reduced to a phosphite triester with iodine.
C)A phosphate triester is reduced to a phosphite triester with tetrazole.
D)A phosphite triester is oxidized to a phosphate triester with tetrazole.
E)A phosphite triester is oxidized to a phosphate triester with NH₄OH.

Question 69

Which of the following statements about the polymerase chain reaction are true?

A)It generates a large number of copies of DNA.
B)It polymerizes the short oligonucleotide strands formed during biosynthesis.
C)It catalyzes the formation of mRNA.
D)It needs a minuscule sample of DNA.
E)Two of these choices.

Question 70

The time required to synthesize a protein depends on the number of amino acid residues it contains.A rough estimate is that each ribosome can cause ___ peptide bonds to be formed per minute.

A)30
B)50
C)100
D)150
E)200

Question 71

What is the antisense nucleotide sequence of ACC GTG CAA GAT

A)TGG CAC CTT GTA
B)ACC GTG CAA GAT
C)UCC CTC GTT CTU
D)TGG CAC GTT CTA
E)ATC TTG CAC GGT

Question 72

The synthesis of proteins according to "the central dogma of molecular genetics" would require:

A)replication then translation.
B)translation then replication.
C)replication then transcription.
D)transcription then translation.
E)Any of these choices.

Question 73

The antisense oligonucleotide G-A-C-T-C,could be synthesized via a ___ template on ___?

A)T-C-A-G-A ,RNA
B)C-T-G-A-G,DNA
C)C-T-G-A-G,RNA
D)G-A-C-T-U,DNA
E)A-G-T-C-T,RNA

Question 74

Which is the initial N-terminal amino acid in the developing polypeptide in bacteria?

A)Cysteine
B)Methionine
C)N-Formylmethionine
D)Glycine
E)Alanine

Question 75

If the base sequence along a segment of DNA were T-C-G-T-A,what would be the antisense oligonucleotide synthesized from this sequence?

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

Question 76

The automated synthesis of oligonucleotides

A)Uses dimethoxytrityl resin as solid phase.
B)Is done in solution phase; the precipitated product is isolated by filtration.
C)Is done in solid phase using an exchange resin and phosphoramidite monomers.
D)Uses controlled pore glass as solid phase and phosphoramidite monomers.
E)Is done in solution phase on a type of glass container that catalyzes the reaction.

Question 77

In DNA sequencing,what is used to convert DNA molecules into smaller,more manageable fragments?

A)DNA polymerase
B)Dilute HCl
C)Trypsin
D)Chymotrypsin
E)Restriction endonucleases

Question 78

Separation of the fragments produced in the chemical sequencing of a DNA segment is achieved by the use of which of these techniques?

A)Column chromatography
B)Fractional distillation
C)Thin layer chromatography
D)Gas chromatography
E)Gel electrophoresis

Question 79

Dimethoxytrityl is used as a protecting group on the 5'-OH of the carbohydrate in the synthesis of DNA.What is the species formed upon cleavage with acid? What factors contribute to its stability?

A)A dimethoxymethyl cation is formed.The cation is stabilized by hyperconjugation and by the donor effect of the OCH₃ groups.
B)A carbanion is formed and this is stabilized by resonance of the benzene rings and by the inductive effect of the OCH₃ groups.
C)A carbocation is formed and this stabilized by inductive effect of the OCH₃ groups as well as by resonance of the negative charge on the benzene ring.
D)A dimethoxytrityl cation is formed.The cation is stabilized by resonance of the benzene rings and by the donor effect of the OCH₃ groups.
E)A neutral dimethoxytrityl is formed.The lack of charge contributes to the easy of hydrolysis and the stability of the species released.

Question 80

What is the acid-labile protecting group used for the carbohydrate during the laboratory synthesis of oligonucleotides.

A)" $\beta$ -Cyanoethyl"
B)"Dimethoxyisopropylamine"
C)"Dimethoxytrityl"
D)"Dimethoxytriptamine"
E)"Phosphoramidite"