Ch. 9 - DNA Structure and Replication

Question 1

Griffith (1928) mixed heat-killed ‘S’ bacteria with ‘R’ bacteria and injected a mouse with both types of bacteria. As a result, the mouse died, and Griffith obtained living ‘S’ bacteria from the dead mouse. He called this process _____.

Answer 1

Transformation

Question 2

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is semi-conservative, and the culture was grown in light media for 1 generation.

Answer 2

Tube B: All of the DNA in the half-heavy position

Question 3

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is conservative, and the culture was grown in light media for 1 generation.

Answer 3

Tube A: Half of the DNA in the light position, half in the heavy position

Question 4

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is semi-conservative, and the culture was grown in light media for 2 generations.

Answer 4

Tube C: Half of the DNA in the light position, half in the half-heavy position

Question 5

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is conservative, and the culture was grown in light media for 2 generations.

Answer 5

Tube A: Half of the DNA in the light position, half in the heavy position

Question 6

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is dispersive, and the culture was grown in light media for 1 generation.

Answer 6

Tube B: All of the DNA in the half-heavy position

Question 7

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

DNA replication is semi-conservative, and the culture was grown in light media for 1 generation, then shifted back to heavy media for 1 more generation.

Answer 7

Tube D: Half of the DNA in the half-heavy position, half in the heavy position

Question 8

Imagine 5 centrifuge tubes subjected to the Meselson-Stahl experiment. DNA can migrate in a ‘light’ position (toward the top of the tube), a ‘heavy’ position toward the bottom of the tube, or a ‘half-heavy’ position in between the ‘light’ and ‘heavy’ bands. ‘Heavy’ is DNA in which both strands carry the heavy isotope of nitrogen (15N), ‘Light’ is DNA that consists of all light isotope of nitrogen (14N), and ‘Half-heavy’ is DNA in which one strand carries 14N and the other carries 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations.

Which tube represents the position expected if the bacteria were never shifted to light media at all?

Answer 8

Tube E: All of the DNA in the heavy position

Question 9

The copying of the information in DNA is straightforward because _____.

Answer 9

Each strand of a DNA molecule carries complementary information

Question 10

Replication occurs at a _____.

Answer 10

Replication fork

Question 11

The DNA double helix is separated into single strands by the enzyme _____.

Answer 11

DNA helicase

Question 12

Short segments of RNA, called _____, are synthesized.

Answer 12

RNA primers

Question 13

Newly-exposed, unreplicated DNA is protected by _____.

Answer 13

Binding proteins

Question 14

The enzyme that synthesizes the short segments of RNA is called a _____.

Answer 14

Primase

Question 15

New DNA is synthesized in the _____ direction.

Answer 15

5’ to 3’

Question 16

The enzyme that catalyzes new DNA synthesis is _____.

Answer 16

DNA polymerase

Question 17

Fragments of discontinuous DNA synthesis are called _____.

Answer 17

Okazaki fragments

Question 18

Gaps in the sugar-phosphate backbone of DNA are closed by _____.

Answer 18

DNA ligase

Question 19

What components are needed to perform PCR?

Answer 19

Target DNA, DNA primers, DNA nucleotides, and Taq1 Polymerase

Question 20

A sequencing reaction generates the following DNA fragments: GTTAC, TTAC, CAGTTAC, AACAGTTAC, C, AC, ACAGTTAC, AGTTAC, and TAC. What was the template sequence of interest for this reaction?

Answer 20

TTGTCAATG

Question 21

Select next-generation sequencing techniques.

Answer 21

Attaching short DNA pieces in a flow cell for sequencing

Adding DNA to tiny beads and using a laser to read the synthesized sequence

Using grapheme to measure how each base disrupts an electrical field

Question 22

You are performing PCR for the first time in the lab. You have all your reagents ready, but you forgot to add adenine. What will be the result of your reaction?

Answer 22

DNA synthesis will occur until the polymerase reaches a thymine in the template strand, and then it will halt.

Question 23

You are performing PCR for the first time in the lab. You have all your reagents ready, but you forgot to add adenine. What will be the result of your reaction?

Answer 23

DNA synthesis will occur until the polymerase reaches a thymine in the template strand, and then it will halt

Question 24

You are working with a novel organism with double stranded DNA and you discover that this organism has 20% adenine in its DNA. What percentage of cytosine do you expect that this organism has in its DNA?

Answer 24

30%

Question 25

What is the complementary DNA strand to the following strand: 5’ - AGGCGGATCGACCGTAC - 3’?

Answer 25

3’ - TCCGCCTAGCTGGCATG - 5’

Question 26

If the DNA fragments below were run on a sequencing gel, which fragment would run nearest to the bottom of the gel?

Answer 26

CC

Question 27

The next-generation sequencing technique in which genome fragments are captured onto a solid surface, and then a copy of each fragment is made and read one base at a time is called _____.

Answer 27

Sequencing by synthesis

Question 28

What type of structure do purines have?

Answer 28

Two-ring

Question 29

Frederick Griffith was a microbiologist who observed that _____.

Answer 29

Nonvirulent bacteria become virulent when mixed with heat-killed virulent bacteria

Question 30

Miescher discovered phosphorus in DNA taken from _____.

Answer 30

Soiled bandages

Question 31

Which of the following were part of the experiments of Hershey and Chase?

Answer 31

E. coli bacteria were infected with virus labeled with radioactive phosphorus

Question 32

Which chemical is not a part of DNA?

Answer 32

Ribose

Question 33

In a DNA molecule, the base pairs provide information, and the sugar-phosphate backbone does not, because _____.

Answer 33

The bases form a sequence, and the sugar-phosphate backbone does not

Question 34

DNA entwined around an octet of proteins is called a(n) _____.

Answer 34

Nucleosome

Question 35

Human DNA can be replicated quickly because it has many _____.

Answer 35

Replication forks

Question 36

Meselson and Stahl’s experiment followed _____.

Answer 36

The distribution of different-weighted DNA over multiple generations of bacteria

Question 37

In a eukaryotic genome, DNA replication starts at _____.

Answer 37

Multiple sites along the length of each chromosome

Question 38

In chain termination sequencing, DNA replication halts in a polymerase chain reaction, owing to the incorporation of a chemically altered base into a growing DNA chain. When this occurs, a _____ results.

Answer 38

Partial DNA molecule