Question 1

Which arrow(s)point(s)to the location of helicase in the diagram shown? 
A)A
B)B
C)C
D)A and E
E)B and D

Accepted Answer

E

Question 2

What is the difference between a nucleotide and a nucleoside?
A)Nucleotides are found in DNA, while nucleosides are found in RNA.
B)Nucleotides are involved in eukaryotic DNA replication, while nucleosides are used in bacterial DNA replication.
C)Nucleosides contain only deoxyribose sugars.
D)A nucleoside with a phosphate ester linked to the sugar is a nucleotide.
E)Nucleosides are purines, while nucleotides are pyrimidines.

Accepted Answer

A nucleoside consists of a nitrogenous base (either a purine or a pyrimidine) attached to a pentose sugar (either ribose or deoxyribose) via a glycosidic bond. A nucleotide, on the other hand, consists of a nucleoside with one or more phosphate groups esterified to the 5'-carbon of the sugar. Hence, a nucleoside with a phosphate ester linked to the sugar is a nucleotide.

Question 3

In 1928, Griffith found that injecting which strains of Pneumococcus caused the mouse to die?
A)living type RII
B)heat-killed type SIII
C)heat-killed type RII
D)heat-killed type SIII and living type RII
E)heat-killed type RII and living type RII

Accepted Answer

Griffith found that injecting heat-killed type SIII and living type RII strains of Pneumococcus caused the mouse to die, while injecting only living type RII or heat-killed type RII did not have fatal effects. This experiment led to the discovery of bacterial transformation and the identification of DNA as the genetic material.

Question 4

Which of the following are classified as pyrimidines?
A)adenine and thymine
B)guanine and cytosine
C)adenine and guanine
D)thymine and cytosine
E)adenine and uracil

Accepted Answer

Pyrimidines are nitrogenous bases that have a single-ring structure. Thymine and cytosine are pyrimidines, while adenine and guanine are purines (double-ring structure). Uracil is also a pyrimidine, but it is not given as one of the answer choices.

Question 5

A portion of one strand of DNA has the sequence 5′ AATGGCTTA 3′. If this strand is used as a template for DNA replication, which of the following correctly depicts the sequence of the newly synthesized strand in the direction in which it will be synthesized?
A)3′ TTACCGAAT 5′
B)5′ TAAGCCATT 3′
C)3′ AATGGCTTA 5′
D)5′ AATGGCTTA 3′

Accepted Answer

During DNA replication, the newly synthesized strand will have the complementary nucleotides to the template strand. Adenine pairs with thymine and guanine pairs with cytosine. Therefore, the sequence of the newly synthesized strand will be 3′ TTACCGAAT 5′, which is the complementary sequence to the template strand 5′ AATGGCTTA 3′. Choice B correctly depicts this sequence.

Question 6

What type of bond is formed between the hydroxyl group of one nucleotide and the phosphate group of an adjacent nucleotide, forming the sugar-phosphate backbone of DNA?
A)glycosidic bond
B)phosphodiester bond
C)ester linkage
D)hydrogen bond
E)ionic bond

Accepted Answer

The bond formed between the hydroxyl group of one nucleotide and the phosphate group of an adjacent nucleotide is a phosphodiester bond. This bond forms the sugar-phosphate backbone of DNA.

Question 7

What is one difference between DNA replication in bacteria versus eukaryotes?
A)Eukaryotic chromosomes are replicated bidirectionally, while bacterial chromosomes are replicated in one direction.
B)Eukaryotic chromosomes have many origins of replication and replicate bidirectionally, while bacteria have only one origin of replication and replicate unidirectionally.
C)Bacterial chromosomes are replicated bidirectionally, while eukaryotic chromosomes are replicated in one direction.
D)Eukaryotic chromosomes have many origins of replication, while bacteria have only one origin of replication.
E)The process is identical in bacterial and eukaryotic DNA replication.

Accepted Answer

Eukaryotic chromosomes have multiple origins of replication to efficiently replicate their larger genomes, while bacterial chromosomes typically have a single origin of replication. Both replicate bidirectionally.

Question 8

The following represents a DNA strand in the process of replication. The bottom sequence is that of the DNA strand with polarity indicated and the top sequence represents the RNA primer. GGGGCCUUU
5′ AAATCCCCGGAAACTAAAC 3′
Which of the following will be the first DNA nucleotide added to the primer?
A)A
B)G
C)C
D)T
E)U

Accepted Answer

The RNA primer ends with a U, which pairs with A in DNA. Therefore, the first DNA nucleotide added will be A.

Question 9

What types of bonds are formed between complementary DNA bases?
A)glycosidic bonds
B)phosphodiester bonds
C)covalent bonds
D)hydrogen bonds
E)ionic bonds

Accepted Answer

Complementary DNA bases are held together by hydrogen bonds.

Question 10

If there is 24% guanine in a DNA molecule, then there is _____ cytosine.
A)24%
B)26%
C)48%
D)52%
E)impossible to determine

Accepted Answer

In DNA, guanine pairs with cytosine, so the percentage of cytosine will be equal to the percentage of guanine, which is 24%.

Question 11

Based on the following replication bubble, which of these statements is true? 
A)X and Y are leading strands, W and Z are lagging strands
B)X and Z are leading strands, W and Y are lagging strands
C)X and W are leading strands, Y and Z are lagging strands
D)W and Z are leading strands, X and Y are lagging strands
E)W and Y are leading strands, X and Z are lagging strands

Accepted Answer

The answer of Based on the following replication bubble, which...

Question 12

If SSB is not present during DNA replication, what would you expect to see?
A)The replisome complex would not assemble on the oriC region.
B)The DNA cannot bend, so hydrogen bonds in the 13-mer region of oriC remain intact.
C)Helicase activity is inhibited, so DNA strands cannot be separated.
D)SSB carries the helicase protein to the open region of DNA, so hydrolysis and strand separation will not occur.
E)SSB prevents reannealing of the separated strands, so strands would quickly reanneal and DNA replication cannot proceed.

Accepted Answer

SSB (Single-Strand Binding protein) prevents the reannealing of separated DNA strands during replication. Without SSB, the strands would quickly reanneal, hindering replication.

Question 13

During DNA replication in E. coli, what is the role of DnaA?
A)DnaA is a region of DNA recognized by the replisome where replication is initiated.
B)DnaA bends DNA, hydrolyzing the hydrogen bonds in the 13-mer region of oriC and creating an open complex.
C)DnaA is a helicase that uses ATP to hydrolyze hydrogen bonds and separate DNA strands.
D)DnaA carries the helicase protein to the open region of DNA where hydrolysis and strand separation will occur.
E)DnaA prevents reannealing of the separated strands so replication can proceed.

Accepted Answer

DnaA binds to specific sequences in the oriC region and forms a complex that bends the DNA and creates an open complex by hydrolyzing the hydrogen bonds in the 13-mer region of oriC. This allows other proteins, such as helicases and polymerases, to access the separated strands for replication.

Question 14

Avery, Macleod, and McCarty expanded on Griffith's experiment to prove that DNA is the hereditary molecule required for transformation. What treatment of the heat-killed SIII bacteria extract resulted in the mouse living?
A)destroying type SIII lipids and polysaccharides
B)destroying type SIII DNA with DNase
C)destroying type SIII RNA with RNase
D)destroying type SIII proteins with protease
E)the control group (null treatment), in which all components are intact

Accepted Answer

If DNA is the hereditary molecule required for transformation, then destroying the type SIII DNA with DNase should prevent transformation and the mouse should live. The other choices would not have a significant impact on transformation because they do not target the DNA molecule. The control group is important for comparing the results of the experimental groups, but it does not provide information about the role of DNA in transformation.

Question 15

In their famous experiment, which of the following would Meselson and Stahl have observed after one cycle of replication in ¹⁴N medium if DNA replication was conservative? A)DNA molecules containing one strand of ¹⁵N-DNA and one strand of ¹⁴N-DNA B)DNA molecules containing two ¹⁵N-DNA strands only C)DNA molecules containing two ¹⁴N-DNA strands only D)An equal number of DNA molecules containing two ¹⁵N-DNA strands and DNA molecules containing two ¹⁴N-DNA strands. E)A mix of DNA molecules corresponding to A and B.

Accepted Answer

In conservative replication, the original DNA molecule remains intact, and a completely new molecule is synthesized. After one cycle in ¹⁴N medium, there would be original DNA with two ¹⁵N strands and new DNA with two ¹⁴N strands.

Question 16

DNA helicase inhibitors are well studied as potential drug targets. What would you expect to see if DNA helicase activity is inhibited?
A)The replisome complex would not assemble on the oriC region.
B)The DNA cannot bend, so hydrogen bonds in the 13-mer region of oriC remain intact.
C)Helicase catalyzes ATP hydrolysis and DNA strands separation, so the helix cannot be unwound and strands will not separate.
D)Helicase carries the SSB protein to the open region of DNA, so hydrolysis and strand separation will not occur.
E)Helicase prevents reannealing of the separated strands, so strands would quickly reanneal and DNA replication cannot proceed.

Accepted Answer

Helicase catalyzes ATP hydrolysis and DNA strands separation. Therefore, if DNA helicase activity is inhibited, the helix cannot be unwound, and strands will not separate.

Question 17

In the Hershey-Chase experiment, what was labeled by growing bacteriophage in ³²P-containing medium? A)ghost phage particles B)proteins C)lipids D)DNA E)RNA

Accepted Answer

In the Hershey-Chase experiment, the bacteriophage was grown in a medium containing ³²P, which labeled only the DNA of the phage with radioactive phosphorus-32 (32P). The proteins were labeled with radioactive sulfur-35 (35S), but were not used in this experiment. Therefore, the best choice is D - DNA was labeled in the experiment.

Question 18

The process by which Pneumococcus transfers DNA between living type RII and heat-killed type SIII cells is known as __________.
A)transformation
B)replication
C)transduction
D)ligation
E)conjugation

Accepted Answer

The process described involves the transfer of DNA from one bacterial strain (heat-killed type SIII) to another (living type RII) through direct uptake of genetic material, which is characteristic of transformation. Replication refers to the copying of existing DNA molecules, transduction involves DNA transfer through viruses, ligation involves joining two DNA fragments together, and conjugation involves transfer of DNA through physical contact between cells.

Question 19

What fraction of the nucleotides in a double-stranded DNA molecule are cytosine and thymine (% C and % T added together)?
A)25 %
B)50 %
C)75 %
D)100%
E)It depends on the DNA sequence

Accepted Answer

The base pairing rules of DNA state that cytosine (C) pairs with guanine (G) and adenine (A) pairs with thymine (T). Therefore, in a double-stranded DNA molecule, the amount of C and G added together will be the same as the amount of A and T added together. Since there are only four nucleotides in DNA (C, G, A, and T), the maximum percentage of C and T added together is 50%. Therefore, the best answer is B) 50%.

Question 20

If complementary DNA strands were arranged in a parallel manner, what would you expect to see?
A)Complementary nucleotides would be attracted to each other, forming ionic bonds that would make the helix stable but not uniform in width.
B)Charges of complementary nucleotides would repel and no hydrogen bonds would form.
C)Complementary nucleotides would line up properly; but fewer hydrogen bonds would form, so the strands could be more easily pulled apart.
D)Purines would pair with both purines and pyrimidines due to the closer alignment of the parallel strands.
E)There would be no discernable difference between DNA strands aligned in a parallel versus an antiparallel manner.

Accepted Answer

The answer of If complementary DNA strands were arranged in...

Quiz 7: Dna Structure and Replication

Which arrow(s) point(s) to the location of helicase in the diagram shown?

What is the difference between a nucleotide and a nucleoside?

In 1928, Griffith found that injecting which strains of Pneumococcus caused the mouse to die?

Which of the following are classified as pyrimidines?

A portion of one strand of DNA has the sequence 5′ AATGGCTTA 3′. If this strand is used as a template for DNA replication, which of the following correctly depicts the sequence of the newly synthesized strand in the direction in which it will be synthesized?

What type of bond is formed between the hydroxyl group of one nucleotide and the phosphate group of an adjacent nucleotide, forming the sugar-phosphate backbone of DNA?

What is one difference between DNA replication in bacteria versus eukaryotes?

What types of bonds are formed between complementary DNA bases?

If there is 24% guanine in a DNA molecule, then there is _____ cytosine.

Based on the following replication bubble, which of these statements is true?

If SSB is not present during DNA replication, what would you expect to see?

During DNA replication in E. coli, what is the role of DnaA?

Avery, Macleod, and McCarty expanded on Griffith's experiment to prove that DNA is the hereditary molecule required for transformation. What treatment of the heat-killed SIII bacteria extract resulted in the mouse living?

In their famous experiment, which of the following would Meselson and Stahl have observed after one cycle of replication in ¹⁴N medium if DNA replication was conservative?

DNA helicase inhibitors are well studied as potential drug targets. What would you expect to see if DNA helicase activity is inhibited?

In the Hershey-Chase experiment, what was labeled by growing bacteriophage in ³²P-containing medium?

The process by which Pneumococcus transfers DNA between living type RII and heat-killed type SIII cells is known as __________.

What fraction of the nucleotides in a double-stranded DNA molecule are cytosine and thymine (% C and % T added together) ?

If complementary DNA strands were arranged in a parallel manner, what would you expect to see?