Question 1

Which one of the following terms best describes the complete structure of a nitrogenous base with oxygens at positions 2 and 4 and ribose at position 1?

Accepted Answer

A)  Thymine 
B)  Uracil 
C)  Thymine ribonucleoside 
D)  Uridine 
E)  Cytidine 
A)  Thymine 
B)  Uracil 
C)  Thymine ribonucleoside 
D)  Uridine 
E)  Cytidine

Question 2

If the tetranucleotide 5' -pGpCpUpA-were treated with a phosphodiesterase which cleaves each phosphodiester bond on the side attached to a carbon, which of the following would be among the products?

Accepted Answer

A)  5' -GMP 
B)  -GMP 
C)  5' -GDP 
D)  adenosine 
E)  -UMP 
A)  5' -GMP 
B)  -GMP 
C)  5' -GDP 
D)  adenosine 
E)  -UMP

Question 3

Which of the following are found in the 60S ribosomal subunit?

Accepted Answer

A)  5S rRNA 
B)  l8S rRNA 
C)  28S rRNA 
D)  Both A and B 
E)  Both A and C 
A)  5S rRNA 
B)  l8S rRNA 
C)  28S rRNA 
D)  Both A and B 
E)  Both A and C

Question 4

Each of the following statements concerning DNA structure is true EXCEPT which one?

Accepted Answer

A)  [A] + [T] = [G] + [C] in normal double stranded DNA. 
B)  [A] + [G] = [T] + [C] in normal double stranded DNA. 
C)  [Purines] = [pyrimidines] in normal double stranded DNA. 
D)  the specificity of base pairing is due to the arrangement of H-bonds found between bases and the dimensions of the base pairs. 
E)  the 5 position on thymine bears a methyl group. 
A)  [A] + [T] = [G] + [C] in normal double stranded DNA. 
B)  [A] + [G] = [T] + [C] in normal double stranded DNA. 
C)  [Purines] = [pyrimidines] in normal double stranded DNA. 
D)  the specificity of base pairing is due to the arrangement of H-bonds found between bases and the dimensions of the base pairs. 
E)  the 5 position on thymine bears a methyl group.

Question 5

What is the difference between ribozymes that are considered "true" catalysts and those that are not?

Accepted Answer

A)  "Non-true" catalysts are found only in prokaryotes 
B)  "Non-true" catalysts do not employ any of the accepted mechanisms of rate enhancement 
C)  "Non-true" catalysts do not recognize a specific site on the substrate 
D)  "True" catalysts are the same at the end of the reaction as at the beginning 
E)  "True" catalysts require a protein component 
A)  "Non-true" catalysts are found only in prokaryotes 
B)  "Non-true" catalysts do not employ any of the accepted mechanisms of rate enhancement 
C)  "Non-true" catalysts do not recognize a specific site on the substrate 
D)  "True" catalysts are the same at the end of the reaction as at the beginning 
E)  "True" catalysts require a protein component

Question 6

The conversion of B_DNA to Z_DNA is facilitated by

Accepted Answer

A)  sequences rich in A-T base pairs. 
B)  increasing NaCl concentration. 
C)  negative supercoiling. 
D)  histone acetylation. 
A)  sequences rich in A-T base pairs. 
B)  increasing NaCl concentration. 
C)  negative supercoiling. 
D)  histone acetylation.

Question 7

Which is not true of the structure of DNA

Accepted Answer

A)  The B form of DNA is anti_parallel 
B)  The Z form of DNA is parallel 
C)  Stacking forces stabilize the Z form of DNA 
D)  DNA RNA hybrids are in the A form 
E)  Hydrophobic interactions provide the negative free energy in base pairing 
A)  The B form of DNA is anti_parallel 
B)  The Z form of DNA is parallel 
C)  Stacking forces stabilize the Z form of DNA 
D)  DNA RNA hybrids are in the A form 
E)  Hydrophobic interactions provide the negative free energy in base pairing

Question 8

Spontaneous conversion of adenine and cytosine from the amino to the imino forms of these bases within DNA results in

Accepted Answer

A)  cleavage of the glycosidic bond and loss of the base. 
B)  cleavage of the 3', 5' phosphodiester DNA backbone. 
C)  alteration of the hydrogen bonding of the bases. 
D)  formation of guanine and thymine. 
A)  cleavage of the glycosidic bond and loss of the base. 
B)  cleavage of the 3', 5' phosphodiester DNA backbone. 
C)  alteration of the hydrogen bonding of the bases. 
D)  formation of guanine and thymine.

Question 9

Each of the following statements concerning the complementary strands of DNA is true EXCEPT which one?

Accepted Answer

A)  The pyrimidine content of each strand is the same. 
B)  The sum of the G and C content in one strand equals the sum of the G and C content in the other strand. 
C)  The percent purines in one strand must equal the percent pyrimidines in the other strand. 
D)  If one strand contains the sequence pGpApApTpTpC, the other strand must contain the same sequence. 
E)  If one strand contains thymine, the other strand must contain adenine. 
A)  The pyrimidine content of each strand is the same. 
B)  The sum of the G and C content in one strand equals the sum of the G and C content in the other strand. 
C)  The percent purines in one strand must equal the percent pyrimidines in the other strand. 
D)  If one strand contains the sequence pGpApApTpTpC, the other strand must contain the same sequence. 
E)  If one strand contains thymine, the other strand must contain adenine.

Question 10

All of the following statements regarding the Watson-Crick B form of DNA are true EXCEPT

Accepted Answer

A)  two chains are coiled around a common axis forming a right-handed helix. 
B)  there are 10 base pairs per turn. 
C)  the bases are found on the outside of the helix and the sugar phosphate backbone on the inside. 
D)  the two chains run in opposite directions. 
E)  adenine is always paired with thymine, guanine with cytosine. 
A)  two chains are coiled around a common axis forming a right-handed helix. 
B)  there are 10 base pairs per turn. 
C)  the bases are found on the outside of the helix and the sugar phosphate backbone on the inside. 
D)  the two chains run in opposite directions. 
E)  adenine is always paired with thymine, guanine with cytosine.

Question 11

Heterochromatin is

Accepted Answer

A)  metabolically inactive regions of chromatin. 
B)  found in the centromere region of the chromosome. 
C)  DNA in the process of being replicated. 
D)  A and B above. 
E)  B and C above. 
A)  metabolically inactive regions of chromatin. 
B)  found in the centromere region of the chromosome. 
C)  DNA in the process of being replicated. 
D)  A and B above. 
E)  B and C above.

Question 12

Posttranslational modification of histone proteins by phosphorylation or acetylation results in

Accepted Answer

A)  dissociation of the histone octamer proteins. 
B)  higher affinity binding between histones and DNA. 
C)  repression of transcription. 
D)  reduction of the overall positive charge of the histones. 
A)  dissociation of the histone octamer proteins. 
B)  higher affinity binding between histones and DNA. 
C)  repression of transcription. 
D)  reduction of the overall positive charge of the histones.

Question 13

Which of the following statements is incorrect concerning the function of chromatin:

Accepted Answer

A)  chromatin condenses the DNA 
B)  chromatin plays a role in the regulation of gene expression 
C)  chromatin allows for the tight packaging of DNA into sperm heads 
D)  chromatin compacts DNA in a manner that allows regulatory sequences to be exposed 
E)  none of the above 
A)  chromatin condenses the DNA 
B)  chromatin plays a role in the regulation of gene expression 
C)  chromatin allows for the tight packaging of DNA into sperm heads 
D)  chromatin compacts DNA in a manner that allows regulatory sequences to be exposed 
E)  none of the above

Question 14

What is the PRINCIPAL force holding the two strands of the double helix together?

Accepted Answer

A)  base pairing 
B)  covalent bonding 
C)  hydrophobic interactions 
D)  stacking forces 
A)  base pairing 
B)  covalent bonding 
C)  hydrophobic interactions 
D)  stacking forces

Question 15

In a plot of temperature versus absorbance of light at 260 nm by DNA, on what does Tm depend?

Accepted Answer

A)  Equilibrium between denatured and renatured species 
B)  Kcat of denaturation 
C)  Length of DNA 
D)  Molecular weight of DNA 
E)  Percent of guanine and adenine bases 
A)  Equilibrium between denatured and renatured species 
B)  Kcat of denaturation 
C)  Length of DNA 
D)  Molecular weight of DNA 
E)  Percent of guanine and adenine bases

Question 16

Which of the following statements is correct concerning native DNA?

Accepted Answer

A)  The two strands are the same in base sequence. 
B)  The sugar-phosphate backbones contain the five carbon sugar ribulose. 
C)  The analysis A = G and C = T is expected. 
D)  The structure can be disrupted by high salt. 
E)  None of the above. 
A)  The two strands are the same in base sequence. 
B)  The sugar-phosphate backbones contain the five carbon sugar ribulose. 
C)  The analysis A = G and C = T is expected. 
D)  The structure can be disrupted by high salt. 
E)  None of the above.

Question 17

What is the nature of the usual linkage between nucleic acids and proteins in nucleoproteins?

Accepted Answer

A)  Hydrogen bonding. 
B)  Covalent ester formation between phosphoric acid of nucleic acids and basic amino acids of proteins. 
C)  Ionic linkages between phosphoric acid of nucleic acids and basic amino acids of proteins. 
D)  Van der Waals interactions between bases of nucleic acids and side chains of amino acids of protein. 
E)  A mixture of covalent linkages and hydrogen bonding. 
A)  Hydrogen bonding. 
B)  Covalent ester formation between phosphoric acid of nucleic acids and basic amino acids of proteins. 
C)  Ionic linkages between phosphoric acid of nucleic acids and basic amino acids of proteins. 
D)  Van der Waals interactions between bases of nucleic acids and side chains of amino acids of protein. 
E)  A mixture of covalent linkages and hydrogen bonding.

Question 18

Histones are

Accepted Answer

A)  found primarily in prokaryotic cells and not in mammalian cells. 
B)  believed to bind with rRNA in the formation of ribosomes. 
C)  acidic proteins containing a high proportion of glutamic and aspartic acid. 
D)  basic proteins containing a high proportion of lysine and arginine. 
E)  proteins that control the rate of translation of mRNA into a protein molecule. 
A)  found primarily in prokaryotic cells and not in mammalian cells. 
B)  believed to bind with rRNA in the formation of ribosomes. 
C)  acidic proteins containing a high proportion of glutamic and aspartic acid. 
D)  basic proteins containing a high proportion of lysine and arginine. 
E)  proteins that control the rate of translation of mRNA into a protein molecule.

Question 19

All of the following statements are correct with regard to chromatin EXCEPT

Accepted Answer

A)  Nonhistone chromosomal proteins are believed to comprise at least several hundred different protein species. 
B)  Histones are proteins which have been conserved during evolution and are rich in basic amino acids. 
C)  The nucleosome is a basic structural subunit of chromatin, consisting of a core of 8 histone molecules and about 140base pairs of DNA. 
D)  Histones are synthesized throughout the cell cycle and turnover occurs during cell growth. 
E)  Most DNA, as it exists in the nucleus, is complexed with proteins. 
A)  Nonhistone chromosomal proteins are believed to comprise at least several hundred different protein species. 
B)  Histones are proteins which have been conserved during evolution and are rich in basic amino acids. 
C)  The nucleosome is a basic structural subunit of chromatin, consisting of a core of 8 histone molecules and about 140base pairs of DNA. 
D)  Histones are synthesized throughout the cell cycle and turnover occurs during cell growth. 
E)  Most DNA, as it exists in the nucleus, is complexed with proteins.

Question 20

DNA sequencing by the Sanger technique makes use of dideoxynucleotides for which of the following reasons?

Accepted Answer

A)  To ensure that DNA is synthesized from only one of the two DNA strands 
B)  To terminate DNA synthesis at every nucleotide 
C)  To promote base-pairing between the newly synthesized strand and the template strand 
D)  To provide sites at which DNA cleavage will occur 
A)  To ensure that DNA is synthesized from only one of the two DNA strands 
B)  To terminate DNA synthesis at every nucleotide 
C)  To promote base-pairing between the newly synthesized strand and the template strand 
D)  To provide sites at which DNA cleavage will occur

Exam 2: DNA and RNA: Composition and Structure

Which one of the following terms best describes the complete structure of a nitrogenous base with oxygens at positions 2 and 4 and ribose at position 1?

If the tetranucleotide 5' -pGpCpUpA-were treated with a phosphodiesterase which cleaves each phosphodiester bond on the side attached to a carbon, which of the following would be among the products?

Which of the following are found in the 60S ribosomal subunit?

Each of the following statements concerning DNA structure is true EXCEPT which one?

What is the difference between ribozymes that are considered "true" catalysts and those that are not?

The conversion of B_DNA to Z_DNA is facilitated by

Which is not true of the structure of DNA

Spontaneous conversion of adenine and cytosine from the amino to the imino forms of these bases within DNA results in

Each of the following statements concerning the complementary strands of DNA is true EXCEPT which one?

All of the following statements regarding the Watson-Crick B form of DNA are true EXCEPT

Heterochromatin is

Posttranslational modification of histone proteins by phosphorylation or acetylation results in

Which of the following statements is incorrect concerning the function of chromatin:

What is the PRINCIPAL force holding the two strands of the double helix together?

In a plot of temperature versus absorbance of light at 260 nm by DNA, on what does Tm depend?

Which of the following statements is correct concerning native DNA?

What is the nature of the usual linkage between nucleic acids and proteins in nucleoproteins?

Histones are

All of the following statements are correct with regard to chromatin EXCEPT

DNA sequencing by the Sanger technique makes use of dideoxynucleotides for which of the following reasons?

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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