Week 2

Question 1

The rate of elongation of a DNA strand in prokaryotes is __________ the rate in eukaryotes.

a) about the same speed as
much slower than
b) much faster than
c) The rates are not comparable because d) elongation only occurs in prokaryotes.
e) sometimes faster and sometimes slower than

Answer 1

b) much faster than

Question 2

Which of the following lists is in order from the entity with the smallest genome to the entity with the largest genome?

a) All the listed entities have about the same amount of DNA.
b) Virus, bacteria, eukaryote
c) Bacteria, virus, eukaryote
d) Bacteria, eukaryote, virus

Answer 2

b) Virus, bacteria, eukaryote

Question 2

The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called __________.

a) topoisomerase
b) primase
c) helicase
d) ligase
e) nuclease

Answer 2

a) topoisomerase

Question 3

A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have __________.

a) the protein and DNA of T2
b) the protein of T4 and the DNA of T2
c) a mixture of the DNA and proteins of both phages
d) the protein of T2 and the DNA of T4
e) the protein and DNA of T4

Answer 3

e) the protein and DNA of T4

Question 4

Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?
a) The helicase pushes the two strands so far apart that they have no chance of finding each other.
b) DNA polymerase follows the helicase so closely that there is no chance for the strands to come back together.
c) Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.
d) One of the strands is rapidly degraded, preventing the double helix from re-forming.
e) The helicase modifies the DNA in such a way as to eliminate the affinity between the two strands.

Answer 4

c) Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.

Question 5

Avery and his colleagues’ 1944 experiment showed that DNA __________.

a) has two strands held together with hydrogen bonds
b) was the substance that transformed the bacteria in Griffith’s experiment
c) consists of sugars, phosphate groups, and bases
d) contains adenine, guanine, thymine, and cytosine
e) uses three bases to code for one amino acid

Answer 5

b) was the substance that transformed the bacteria in Griffith’s experiment

Question 6

During Griffith’s experiments with Streptococcus pneumoniae in mice, material from __________ bacteria transformed __________ bacteria.

a) heat-killed virulent; living nonvirulent
b)living nonvirulent; heat-killed virulent
c) living virulent; heat-killed nonvirulent
d)living nonvirulent; living virulent
e) heat-killed nonvirulent; living virulent

Answer 6

a) heat-killed virulent; living nonvirulent

Question 7

The experiments of Meselson and Stahl showed that DNA __________.

a) is the genetic material
b) replicates in a semiconservative fashion
c) is composed of nucleotides
d) contains complementary base pairing
e) codes for the sequence of amino acids in protein

Answer 7

b) replicates in a semiconservative fashion

Question 8

The overall error rate in a completed DNA molecule is approximately __________.

a) one error per 100 nucleotides
b) one error per 1,000,000,000 nucleotides
c) one error per 1,000 nucleotides
d) one error per 10,000,000,000 nucleotides
e) one error per 1,000,000 nucleotides

Answer 8

d) one error per 10,000,000,000 nucleotides

Question 9

The incorporation of an incorrect base into a DNA molecule during replication __________.
a) is virtually impossible, as the accuracy of DNA polymerase is such that errors almost never occur
b) ends replication of the molecule
c) will almost certainly lead to the death of the cell
d) will catalyze additional mutations
e) can be repaired by the mismatch repair system

Answer 9

e) can be repaired by the mismatch repair system

Question 10

The two strands of a DNA double helix are antiparallel. This means that __________.
a) they both run in the 3’ to 5’ direction
b) one strand runs in the 5’ to 3’ direction and the other runs in the 3’ to 5’ direction
c) one strand is actually composed of RNA
d) only one of the two strands can be used as a template for replication because DNA polymerase only works in one direction
e) the two strands are mirror image

Answer 10

b) one strand runs in the 5’ to 3’ direction and the other runs in the 3’ to 5’ direction

Question 11

What enzyme joins Okazaki fragments?
a) Primase
b) Helicase
c) DNA ligase
d) Topoisomerase
e) nuclease

Answer 11

c) DNA ligase

Question 12

The role of DNA polymerases in DNA replication is to __________.

a) attach free nucleotides to the new DNA strand
b) link together short strands of DNA
c) All of the listed responses are correct.
d) separate the two strands of DNA
e) synthesize an RNA primer to initiate DNA strand synthesis

Answer 12

a) attach free nucleotides to the new DNA strand

Question 13

What technique was most helpful to Watson and Crick in developing their model for the structure of DNA?

a) X-ray crystallography
b) Transgenic animals
c) Cloned DNA
d) Gel electrophoresis

Answer 13

a) X-ray crystallography

Question 14

The type of mutation responsible for sickle-cell anemia is __________.

a) a nucleotide-pair insertion
b) a silent mutation
c) both a point mutation and a nucleotide-pair substitution
d) a point mutation
e) a nucleotide-pair substitution

Answer 14

c) both a point mutation and a nucleotide-pair substitution

Question 15

RNA polymerase __________.

a) is the molecule of which ribosomes are constructed
b) is a ribozyme
c) moves along the template strand of DNA, elongating an RNA molecule in a 5′ → 3′ direction
d) is the enzyme that catalyzes the joining of each amino acid to the right tRNA
e) is the enzyme that transcribes exons but does not transcribe introns

Answer 15

c) moves along the template strand of DNA, elongating an RNA molecule in a 5′ → 3′ direction

Question 16

Why were many of the early experiments on DNA carried out on viruses and bacteria?

a) They can interact with each other.
b) All of the listed responses are correct.
c)They have short generation times.
d)Their chromosomes have a simpler structure.
e) They have relatively small genomes

Answer 16

b) All of the listed responses are correct.

Question 17

There are how many types of bacterial RNA polymerase?

a) Zero
b) Five
c) Hundreds
d) Three
e) One

Answer 17

e) One

Question 18

he backbone of a double-stranded DNA molecule consists of which of the following?

a) hydrogen bonds
b) antiparallel sugar-phosphate polymers
c) purine-pyrimidine base-pairs
d) Van der Waals interactions
e) polysaccharide polymers

Answer 18

a) hydrogen bonds

Question 19

Who conducted the X-ray diffraction studies that were the key to the discovery of the structure of DNA?

a) Levene
b) Avery
c) Griffith
d) Franklin
e) Chargaff

Answer 19

d) Franklin

Question 20

Which of the following statements concerning the structure of DNA is correct?
a) Adenine forms three covalent bonds with thymine; guanine forms two covalent bonds with cytosine.
b) Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine.
c) Adenine forms three hydrogen bonds with thymine; guanine forms two hydrogen bonds with cytosine.
d) Adenine forms two covalent bonds with thymine; guanine forms three covalent bonds
e) Adenine forms two hydrogen bonds with guanine; thymine forms three hydrogen bonds with cytosine.

Answer 20

b) Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine.

Question 21

Suppose a double-stranded DNA molecule was shown to have 20% adenine bases. What would be the expected percentage of cytosine bases in that molecule?

a) 35%
b) not enough information
c) 70%
d) 30%
e) 15%

Answer 21

d) 30%

Question 22

Eukaryotic DNA replication overall has very high fidelity. Which of the following phenomena or processes contributes to this high fidelity?

a) relatively slow speed of replication
b) proofreading
c) mismatch repair
d) all of the above
e) base pairing

Answer 22

d) all of the above

Question 23

Who is credited with discovering the structure of the DNA double helix?

a) Jacob and Monod
b) Avery, McCarty, and MacLeod
c) Watson and Crick
d) Hershey and Chase
e) Griffith

Answer 23

c) Watson and Crick

Question 24

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules? a) A=G b) C=T c) A+G=C+T d) A=C e) A+T=G+C

Answer 24

c) A+G=C+T

Question 25

The elongation of the leading strand during DNA synthesis a) occurs in 5’->3’ direction b) progresses away from the replication fork c) occurs in the 3’->5’ direction d) produces Okazaki fragments e) does not depend on the action of DNA polymerase

Answer 25

a) occurs in 5’->3’ direction

Question 26

In his work with pneumonia-causing bacteria and mice, Griffith found that a) the protein coat from pathogenic cells was able to transform nonpathogenic cells b) the polysaccharide coat of bacteria caused pneumonia c) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic d) none of the above e) heat-killed pathogenic cells caused pneumonia

Answer 26

c) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic

Question 27

The nontemplate DNA strand of a portion of a gene reads 5’ AGGTCCG-3’. What is the complimentary matching template DNA sequence? a) 5’-TCCAGGC-5’ b) 3’-GCCAGGC-5’ c) none of the above d) 3’-TCCAGGC-5’ e) 5’-GCCAGGC-3’

Answer 27

d) 3’-TCCAGGC-5’

Question 28

What is the major difference between bacterial chromosomes and eukaryotic chromosomes? a) The DNA of bacterial chromosomes has a slightly different structure. b) Bacterial chromosomes have much more protein associated with the DNA than eukaryotes. c) Bacteria have a single circular chromosome, whereas eukaryotes have several linear chromosomes. d) Eukaryotes have a single circular chromosome, whereas bacteria have several linear chromosomes. e) There is no difference between bacterial and eukaryotic chromosomes.

Answer 28

c) Bacteria have a single circular chromosome, whereas eukaryotes have several linear chromosomes.

Question 29

Which description of DNA replication is correct? a) The two strands of DNA separate, and restriction enzymes cut up one strand. Then, the DNA polymerase synthesizes two new strands out of the old ones. b) The two strands separate, and each one receives a complementary strand of RNA. Then this RNA serves as a template for the assembly of many new strands of DNA. c) Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates. d) Ligase separates the two strands of the DNA double helix. Then, DNA polymerase synthesizes the leading strand and primase synthesizes the lagging strand. e) Ligase assembles single-stranded codons, then polymerase knits these codons together into a DNA strand.

Answer 29

c) Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.

Question 30

In what way(s) is our traditional representation of DNA polymerase molecules moving like locomotives along a track inaccurate? a) The proteins involved in replication do not move; instead, DNA is drawn through the complex. b) Like a train on a track, DNA polymerase must add nucleotides sequentially. It cannot jump around. c) DNA polymerase acts as part of a large complex of proteins, not like a single locomotive. d) Both the first and second answers are correct. e) DNA polymerase completes replication of one strand and then begins the other.

Answer 30

d) Both the first and second answers are correct.

Question 31

Which set of enzymes is involved in nucleotide excision repair? a) nuclease, DNA polymerase, primase b) DNA polymerase, helicase, primase c) nuclease, DNA polymerase, and ligase d) ligase, nuclease, and primase e) hydrolase, nuclease, and ligase

Answer 31

c) nuclease, DNA polymerase, and ligase

Question 31

The alpha helix and beta pleated sheet are examples of which level of protein structure? a) Primary structure b) Secondary structure c) Beta-turn structure d) Quaternary structure e) None of the listed choices is correct.

Answer 31

b) Secondary structure

Question 32

How many peptide bonds are present in a polypeptide chain that contains 12 amino acids? a) 11 b) 22 c) None of the listed choices is correct. d) 0 e) 6

Answer 32

a) 11

Question 33

Assuming each turn of an alpha helix contains 3.6 amino acids, how many turns of the helix will a segment of 18 amino acids form? a) 5 b) 2.5 c) 10 d) 0

Answer 33

a) 5

Question 34

Which structural level of proteins is characterized by the sequence of amino acids? a) Primary structure b) Tertiary structure c) Quaternary structure d) Secondary structure e) Alpha-helix structure

Answer 34

a) Primary structure

Question 35

A protein loses its three-dimensional structure and becomes inactive. This process is known as: a) Denaturation b) None of the listed choices is correct. c) Renaturation d) Phosphorylation e) Enzymatic

Answer 35

a) Denaturation

Question 36

Which of the following is a feature/features of the tertiary structure of a protein? a) Amino acid sequence b) Hydrophobic interactions, Disulfide bridges c) Disulfide bridges d) Hydrophobic interactions e) Peptide bonds

Answer 36

b) Hydrophobic interactions, Disulfide bridges

Question 37

If you were given a sample of a polysaccharide and told that the only subunit was glucose, what would you have? A. glycogen B. starch C. cellulose D. amylopectin E. You cannot know from the information given.

Answer 37

E. You cannot know from the information given. Glucose is the subunit for all of the polysaccharides listed

Question 38

a small protein insulin is 51 amino acids long but plays a very important role. Many diabetics are insulin deficient/resistant! How many ways in which it can be arranged? A. 20^ 51 ways B. 51^20 ways C. 2^51 ways D. 5^21 ways E. None of the above

Answer 38

A. 20^ 51 ways

Question 39

All of the following pairs are correct matches for polymer/monomer, EXCEPT A. Cellulose/glucose B. Protein/amino acids C. DNA/nucleotides D. Lipid/fatty acids E. RNA/nucleotides

Answer 39

D. Lipid/fatty acids Lipids are not true polymers

Question 40

The backbone of a double-stranded DNA molecule consists of which of the following? A. Van der Waals interactions B. hydrogen bonds C. purine-pyrimidine base-pairs D. antiparallel sugar-phosphate polymers

Answer 40

D. antiparallel sugar-phosphate polymers

Question 41

What is a complimentary matching DNA sequence to 5’- AGCTATC- 3’? A. 3’- UCGAUAG -5’ B. 3’ -TCGATAG - 5’ C. 5’- TCGATAG - 3’ D. None of the above

Answer 41

B. 3’ -TCGATAG - 5’

Question 42

After the formation of a replication bubble, which of the following is the correct sequence of enzymes used for the synthesis of the lagging DNA strand? a) helicases, primase, DNA polymerases, ligase b) helicases, primase, ligase, DNA polymerases c) primase, helicases, DNA polymerases, ligase d) helicases, DNA polymerases, primase, ligase e) ligase, primase, DNA polymerases, helicases

Answer 42

a) helicases, primase, DNA polymerases, ligase

Question 43

Which of the following best describes the arrangement of genetic information in a DNA molecule? a) By analyzing the linear order of amino acids in a polypeptide, the exact order of the three-nucleotide words of a gene arranged on the template strand of DNA can be determined. b) By overlapping the three-nucleotide words of a gene, the amount of information a DNA molecule can hold is maximized. c) The three-nucleotide words of a gene are arranged in a non-overlapping series on the DNA template strand. d) The three-nucleotide words of a gene are serially arranged on both strands of DNA at a specific locus. e) A gene is composed of overlapping, three-nucleotide words on a template strand of DNA

Answer 43

c) The three-nucleotide words of a gene are arranged in a non-overlapping series on the DNA template strand.

Question 44

Monomers for the synthesis of DNA are called __________. a) nucleotides b) fatty acids c)amino acids d) monosaccharides e) disaccharides

Answer 44

a) nucleotides

Question 45

The "primary structure" of a protein refers to __________. a) the weak aggregation of two or more polypeptide chains into one functional macromolecule b) the sequence of amino acids c) interactions among the side chains or R groups of the amino acids d) coiling due to hydrogen bonding between amino acids e) the alpha helix or beta pleated sheets

Answer 45

b) the sequence of amino acids interactions among the side

Question 46

The peptide bond is __________. a) a covalent bond joining nucleotides together to form a nucleic acid b) a covalent bond joining amino acids together to form a polypeptide c) a hydrogen bond joining nucleotides together to form a nucleic acid d) a hydrogen bond joining amino acids together to form a polypeptide e) a covalent bond joining simple sugars together to form a polypeptide

Answer 46

b) a covalent bond joining amino acids together to form a polypeptide

Question 47

At each end of a DNA replication bubble is __________. a) an origin of replication b) a replication fork c) a gene d) a telomere e) a ribosome

Answer 47

b) a replication fork

Question 48

The overall three-dimensional shape of a single polypeptide is called the __________. a) primary structure b) tertiary structure c) quaternary structure d) double helix e) secondary structure

Answer 48

b) tertiary structure

Question 49

During the replication of DNA, __________. a) the reaction does not require any enzymes b) only one strand of the molecule acts as a template c) the reaction is catalyzed by RNA polymerase d) both strands of a molecule act as templates e) errors never occur

Answer 49

d) both strands of a molecule act as templates

Question 50

Which of the following functional groups is present in all amino acids? a)-NH2 b) -OH c) =C=O d) All of the listed responses are correct e)-SH

Answer 50

a)-NH2

Question 51

In a eukaryotic cell, transcription takes place __________. a) on free ribosomes b) in the cytoplasm c) in the rough endoplasmic reticulum d) in the nucleus e)on the cell membrane

Answer 51

d) in the nucleus

Question 52

How is the template strand for a particular gene determined? a) It is established by the presence of the promoter. b) It doesn’t matter which strand is the template because they are complementary and will produce the same mRNA. d) It is the DNA strand that runs from the 5′ → 3′ direction. e) It is signaled by a polyadenylation signal sequence.

Answer 52

a) It is established by the presence of the promoter.

Question 53

One strand of a DNA molecule has the following sequence: 3'-AGTACAAACTATCCACCGTC-5'. In order for transcription to occur in that strand, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated. a) AUG codon b) centromere c) intron d) promoter e) exon

Answer 53

d) promoter

Question 54

To what does the term polypeptide refer? a) A complex carbohydrate b) None of the listed responses are correct. c) Monomers linked by glycosidic linkages d) Amino acids linked by hydrolysis e) Carbohydrates with a hydrogen bond holding them together

Answer 54

b) None of the listed responses are correct.

Question 55

The information in DNA is contained in __________. a) the sequence of nucleotides along the length of the two strands of the DNA molecule b) All of the listed responses are correct. c) the variation in the structure of nucleotides that make up the DNA molecule d) the types of sugars used in making the DNA molecule the e) the sequence of amino acids that makes up the DNA molecule

Answer 55

b) All of the listed responses are correct.

Question 56

Protein molecules are polymers (chains) of __________. a) sucrose molecules b) DNA molecules c) purines and pyrimidines d) fatty acid molecules e) amino acid molecules

Answer 56

e) amino acid molecules

Question 57

What do neurodegenerative diseases such as Alzheimer’s and Parkinson’s have in common? a) They all cause the misfolding of nucleic acids in brain cells. b) All are associated with the buildup of lipids in brain cells due to faulty lysosome activity. c) They all associated with plaque buildup in arteries (atherosclerosis). d) None of the responses is correct. e) All have been associated with the buildup of misfolded proteins

Answer 57

e) All have been associated with the buildup of misfolded proteins

Question 58

At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred __________. a) in a double-stranded DNA molecule b) during transcription c) when an mRNA codon paired with a tRNA anticodon d) It is impossible to say, given this information. e)during translation

Answer 58

b) during transcription

Question 59

What is a key difference in gene expression between eukaryotic and prokaryotic cells? a) RNA polymerases are involved only in initiation in eukaryotes. b) Prokaryotes do not contain ribosomes. c) In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing. d) In prokaryotes, proteins are assembled directly from DNA. e) In eukaryotic cells, transcribed RNA sequences function as termination signals.

Answer 59

c) In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing.

Question 60

Generally speaking, how many genetic codes are there?

Answer 60

one

Question 61

The R group of amino acids is always attached to a a) None of the above. b) hydrogen atom c) carbon atom d) oxygen atom e) nitrogen atoms

Answer 61

c) carbon atom

Question 62

What is DNA? a) The substance of heredity b) A component of chromosomes c) A code for protein synthesis d) A double helix made of four types of nucleotides e) All of the listed responses are correct.

Answer 62

e) All of the listed responses are correct.

Question 63

DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments). a) 5' end … 5' end b) 3' end … 5' end c) 3' end … 3' end d) sugar group … phosphate group e)5' end … 3' end

Answer 63

c) 3' end … 3' end

Question 64

When RNA is being made, the RNA base __________ always pairs with the base __________ in DNA. a) A … U b) U … T c) T … A d) T … G e) U … A

Answer 64

e) U … A