Question 1

Which best describes the mechanism of OH--mediated denaturation of DNA?

Accepted Answer

A)  OH- disrupts the H-bonding between the nitrogenous bases of opposing DNA strands. 
B)  OH- hydrolyzes the phosphodiester linkages between nucleotides. 
C)  The hydroxyl ions attract the unpaired electrons of the amino groups attached to the nitrogenous bases. 
D)  Alkali tends to increase the melting temperature of DNA. 
A)  OH- disrupts the H-bonding between the nitrogenous bases of opposing DNA strands. 
B)  OH- hydrolyzes the phosphodiester linkages between nucleotides. 
C)  The hydroxyl ions attract the unpaired electrons of the amino groups attached to the nitrogenous bases. 
D)  Alkali tends to increase the melting temperature of DNA.

Question 2

In mammalian cells, rRNA

Accepted Answer

A)  accounts for of the total cellular RNA content. 
B)  is rapidly degraded during protein synthesis. 
C)  is composed of only two types - 2and 16S. 
D)  contains the codons for protein synthesis. 
E)  is composed of at least 4 different size classes of RNA. 
A)  accounts for of the total cellular RNA content. 
B)  is rapidly degraded during protein synthesis. 
C)  is composed of only two types - 2and 16S. 
D)  contains the codons for protein synthesis. 
E)  is composed of at least 4 different size classes of RNA.

Question 3

All of the following statements about histones are correct EXCEPT?

Accepted Answer

A)  They are reversibly modified after their assembly into nucleosomes. 
B)  Their amino acid sequences are highly conserved throughout evolution. 
C)  They account for approximately one_half the mass of a eukaryotic chromosome. 
D)  They bind DNA in a sequence specific fashion. 
A)  They are reversibly modified after their assembly into nucleosomes. 
B)  Their amino acid sequences are highly conserved throughout evolution. 
C)  They account for approximately one_half the mass of a eukaryotic chromosome. 
D)  They bind DNA in a sequence specific fashion.

Question 4

Which one of the facts about DNA in the sets listed below is INCORRECT?

Accepted Answer

A)  DNA contains equal amounts of A, T, G, and C on a molar basis. 
B)  The molar content of adenine in a two stranded DNA molecule is equal to the molar content of thymine. 
C)  The resistance of DNA to denaturation by heat can be directly related to the G + C content. 
D)  Denaturation of DNA is associated with an increase in ultraviolet absorption. 
E)  At neutral pH DNA has a large net negative charge. 
A)  DNA contains equal amounts of A, T, G, and C on a molar basis. 
B)  The molar content of adenine in a two stranded DNA molecule is equal to the molar content of thymine. 
C)  The resistance of DNA to denaturation by heat can be directly related to the G + C content. 
D)  Denaturation of DNA is associated with an increase in ultraviolet absorption. 
E)  At neutral pH DNA has a large net negative charge.

Question 5

Restriction endonucleases are enzymes that

Accepted Answer

A)  synthesize DNA from a RNA primer. 
B)  nick single strands of DNA. 
C)  cleave both strands of DNA at sequence specific sites. 
D)  add nucleotides to the end of DNA strands. 
E)  None of the other answers is correct. 
A)  synthesize DNA from a RNA primer. 
B)  nick single strands of DNA. 
C)  cleave both strands of DNA at sequence specific sites. 
D)  add nucleotides to the end of DNA strands. 
E)  None of the other answers is correct.

Question 6

All of the following are TRUE regarding restriction endonucleases EXCEPT

Accepted Answer

A)  they recognize specific palindromic sequences. 
B)  they may produce staggered ends when they cleave DNA into fragments. 
C)  they may produce flush ends when they cleave DNA into fragments. 
D)  they are used in gene cloning to cleave the single stranded regions of the cDNA produced by reverse transcriptase. 
E)  they are used to cleave plasmid DNA in specific places in gene cloning experiments. 
A)  they recognize specific palindromic sequences. 
B)  they may produce staggered ends when they cleave DNA into fragments. 
C)  they may produce flush ends when they cleave DNA into fragments. 
D)  they are used in gene cloning to cleave the single stranded regions of the cDNA produced by reverse transcriptase. 
E)  they are used to cleave plasmid DNA in specific places in gene cloning experiments.

Question 7

Restriction endonucleases

Accepted Answer

A)  digest DNA duplex molecules from the 5'-OH ends. 
B)  attack only single stranded DNA. 
C)  have base sequence specificity. 
D)  randomly digest double stranded DNA molecules. 
E)  are not produced by bacteria. 
A)  digest DNA duplex molecules from the 5'-OH ends. 
B)  attack only single stranded DNA. 
C)  have base sequence specificity. 
D)  randomly digest double stranded DNA molecules. 
E)  are not produced by bacteria.

Question 8

Which of the following determines the specificity of nucleic acid hybridization?

Accepted Answer

A)  base composition 
B)  A-T and G-C hydrogen bonds 
C)  sequence complexity 
D)  stacking interactions 
E)  wobble rules 
A)  base composition 
B)  A-T and G-C hydrogen bonds 
C)  sequence complexity 
D)  stacking interactions 
E)  wobble rules

Question 9

The Watson-Crick model of the DNA double-helix led to the prediction that DNA replication is semi-conservative because

Accepted Answer

A)  the phosphate backbones could be easily broken and rejoined. 
B)  the double-helix can assume either B-form or Z-form higher order structure before DNA replication. 
C)  each strand could serve as a template for daughter strand synthesis producing pairs of identical molecules. 
D)  the hydrogen bonds would stabilize important intermediates that arise during synthesis. 
E)  it would position the reactive OH favorably for formation of the phosphodiester bond. 
A)  the phosphate backbones could be easily broken and rejoined. 
B)  the double-helix can assume either B-form or Z-form higher order structure before DNA replication. 
C)  each strand could serve as a template for daughter strand synthesis producing pairs of identical molecules. 
D)  the hydrogen bonds would stabilize important intermediates that arise during synthesis. 
E)  it would position the reactive OH favorably for formation of the phosphodiester bond.

Question 10

In the double helical structure of DNA, adenine is hydrogen bonded to

Accepted Answer

A)  uridine. 
B)  cytosine. 
C)  guanine. 
D)  thymine. 
A)  uridine. 
B)  cytosine. 
C)  guanine. 
D)  thymine.

Question 11

Which one of the following statements is true? In chromatin folding, the structure called a solenoid:

Accepted Answer

A)  is the most compact form of DNA. 
B)  requires the presence of histone H1. 
C)  is a good template for transcription. 
D)  consists of eight histone molecules around which DNA is wrapped. 
E)  is the most extended form of DNA. 
A)  is the most compact form of DNA. 
B)  requires the presence of histone H1. 
C)  is a good template for transcription. 
D)  consists of eight histone molecules around which DNA is wrapped. 
E)  is the most extended form of DNA.

Question 12

The stem-loop structure of tRNA is associated with which of the following important functional regions?

Accepted Answer

A)  the anti-codon site 
B)  the amino acid attachment site 
C)  the 5' cap site 
D)  the polyadenylation site 
E)  the intron 
A)  the anti-codon site 
B)  the amino acid attachment site 
C)  the 5' cap site 
D)  the polyadenylation site 
E)  the intron

Question 13

All of the following statements regarding ribosomes are CORRECT EXCEPT

Accepted Answer

A)  prokaryotic ribosomes are LESS complex than eukaryotic ribosomes. 
B)  the prokaryotic small ribosomal subunit contains a single rRNA molecule. 
C)  prokaryotic ribosomes resemble mitochondrial ribosomes. 
D)  prokaryotic and eukaryotic LARGE ribosomal subunits each contain different rRNA species. 
E)  prokaryotic small ribosomal subunits contain a nucleotide sequence in rRNA which is complementary to a sequence in mRNA. 
A)  prokaryotic ribosomes are LESS complex than eukaryotic ribosomes. 
B)  the prokaryotic small ribosomal subunit contains a single rRNA molecule. 
C)  prokaryotic ribosomes resemble mitochondrial ribosomes. 
D)  prokaryotic and eukaryotic LARGE ribosomal subunits each contain different rRNA species. 
E)  prokaryotic small ribosomal subunits contain a nucleotide sequence in rRNA which is complementary to a sequence in mRNA.

Question 14

Histones

Accepted Answer

A)  account for 1/4 the mass of the eukaryotic chromosome. 
B)  complex with RNA to form spliceosomes. 
C)  are bound to DNA in the transcriptional units of both active and inactive genes. 
D)  are small Glu+Asp- rich proteins that facilitate compaction of eukaryotic DNA in the nucleus. 
E)  are a highly conserved class of proteins with the most conserved being the linker histone Hl. 
A)  account for 1/4 the mass of the eukaryotic chromosome. 
B)  complex with RNA to form spliceosomes. 
C)  are bound to DNA in the transcriptional units of both active and inactive genes. 
D)  are small Glu+Asp- rich proteins that facilitate compaction of eukaryotic DNA in the nucleus. 
E)  are a highly conserved class of proteins with the most conserved being the linker histone Hl.

Question 15

The structural stability of the double helix of DNA is ascribed in part to

Accepted Answer

A)  hydrogen bonding between adjacent purine bases. 
B)  ionic bonding between stacked purine and pyrimidine nuclei. 
C)  hydrogen bonding between adjacent pyrimidine bases. 
D)  the helical structure of the molecule. 
E)  hydrogen bonding between purine and pyrimidine bases. 
A)  hydrogen bonding between adjacent purine bases. 
B)  ionic bonding between stacked purine and pyrimidine nuclei. 
C)  hydrogen bonding between adjacent pyrimidine bases. 
D)  the helical structure of the molecule. 
E)  hydrogen bonding between purine and pyrimidine bases.

Question 16

By which of the following means are the nucleosides linked to one another in RNA and DNA molecules?

Accepted Answer

A)  They are linked together by alpha-glycosidic bonds. 
B)  They are linked together by beta-glycosidic bonds. 
C)  They are linked together by 5' phosphodiester bridges. 
D)  They are linked together by 2',5' phosphodiester bridges. 
E)  None of the other answers is correct. 
A)  They are linked together by alpha-glycosidic bonds. 
B)  They are linked together by beta-glycosidic bonds. 
C)  They are linked together by 5' phosphodiester bridges. 
D)  They are linked together by 2',5' phosphodiester bridges. 
E)  None of the other answers is correct.

Question 17

Which of these statements is not true regarding the three classes of RNA, ribosomal RNA, mRNA and tRNA?

Accepted Answer

A)  All three classes are involved in protein synthesis. 
B)  Ribosomal RNA is cleaved from a large precursor RNA species. 
C)  tRNA and ribosomal RNA contain methylated bases. 
D)  A single amino acyl tRNA synthetase can attach different amino acids to -C-C-A-OH end of tRNA molecules. 
A)  All three classes are involved in protein synthesis. 
B)  Ribosomal RNA is cleaved from a large precursor RNA species. 
C)  tRNA and ribosomal RNA contain methylated bases. 
D)  A single amino acyl tRNA synthetase can attach different amino acids to -C-C-A-OH end of tRNA molecules.

Question 18

Denaturation of double_stranded DNA with heat or alkali results in all of the following EXCEPT

Accepted Answer

A)  decreased absorbance of the DNA at 260 nm. 
B)  loss of base stacking. 
C)  formation of single_stranded DNA. 
D)  disruption of hydrogen bonding. 
E)  a helix_to_coil transition. 
A)  decreased absorbance of the DNA at 260 nm. 
B)  loss of base stacking. 
C)  formation of single_stranded DNA. 
D)  disruption of hydrogen bonding. 
E)  a helix_to_coil transition.

Question 19

Histones are

Accepted Answer

A)  basic proteins associated with RNA. 
B)  basic proteins associated with DNA. 
C)  acidic proteins which bind chromosomal nucleoprotein. 
D)  proteins exclusively found in the nucleolus. 
E)  proteins which are tissue specific. 
A)  basic proteins associated with RNA. 
B)  basic proteins associated with DNA. 
C)  acidic proteins which bind chromosomal nucleoprotein. 
D)  proteins exclusively found in the nucleolus. 
E)  proteins which are tissue specific.

Question 20

The term denaturation, when used in connection with nucleic acids or proteins refers to a change in structural characteristics due to

Accepted Answer

A)  the disruption of covalent bonds. 
B)  the disruption of non-covalent bonds. 
C)  the binding of toxic compounds. 
D)  changes in primary structure. 
E)  changes in the state of aggregation. 
A)  the disruption of covalent bonds. 
B)  the disruption of non-covalent bonds. 
C)  the binding of toxic compounds. 
D)  changes in primary structure. 
E)  changes in the state of aggregation.

Exam 2: DNA and RNA: Composition and Structure

Which best describes the mechanism of OH--mediated denaturation of DNA?

In mammalian cells, rRNA

All of the following statements about histones are correct EXCEPT?

Which one of the facts about DNA in the sets listed below is INCORRECT?

Restriction endonucleases are enzymes that

All of the following are TRUE regarding restriction endonucleases EXCEPT

Restriction endonucleases

Which of the following determines the specificity of nucleic acid hybridization?

The Watson-Crick model of the DNA double-helix led to the prediction that DNA replication is semi-conservative because

In the double helical structure of DNA, adenine is hydrogen bonded to

Which one of the following statements is true? In chromatin folding, the structure called a solenoid:

The stem-loop structure of tRNA is associated with which of the following important functional regions?

All of the following statements regarding ribosomes are CORRECT EXCEPT

Histones

The structural stability of the double helix of DNA is ascribed in part to

By which of the following means are the nucleosides linked to one another in RNA and DNA molecules?

Which of these statements is not true regarding the three classes of RNA, ribosomal RNA, mRNA and tRNA?

Denaturation of double_stranded DNA with heat or alkali results in all of the following EXCEPT

Histones are

The term denaturation, when used in connection with nucleic acids or proteins refers to a change in structural characteristics due to

Eukaryotic Cell Structure

Protein I: Composition and Structure

DNA Replication, Recombination, and Repair

RNA: Transcription and Rna Processing

Protein Synthesis: Translation and Posttranslational Modifications

Recombinant Dna and Biotechnology

Regulation of Gene Expression

Protein II: Structure-Function Relationships in Protein Families

Enzymes: Classification, Kinetics, and Control

The Cytochromes P450 and Nitric Oxide Synthases

Biological Membranes: Structure and Membrane Transport

Fundamentals of Signal Transduction

Bioenergetics and Oxidative Metabolism

Carbohydrate Metabolism I: Major Metabolic Pathways and Their Control

Carbohydrate Metabolism II: Special Pathways and Glycoconjugates

Lipid Metabolism I: Synthesis, Storage, and Utilization of Fatty Acids and Triacylglycerols

Lipid Metabolism II: Pathways of Metabolism of Special Lipids

Amino Acid Metabolism

Purine and Pyrimidine Nucleotide Metabolism

Metabolic Interrelationships

Biochemistry of Hormones

Molecular Cell Biology

Cell Cycle, Programmed Cell Death, and Cancer

Digestion and Absorption of Basic Nutritional Constituents

Digestion and Absorption of Basic Nutritional Constituents

Principles of Nutrition I and II

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