Ch. 9 - DNA Structure and Replication Flashcards
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 _____.
Transformation
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.
Tube B: All of the DNA in the half-heavy position
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.
Tube A: Half of the DNA in the light position, half in the heavy position
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.
Tube C: Half of the DNA in the light position, half in the half-heavy position
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.
Tube A: Half of the DNA in the light position, half in the heavy position
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.
Tube B: All of the DNA in the half-heavy position
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.
Tube D: Half of the DNA in the half-heavy position, half in the heavy position
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?
Tube E: All of the DNA in the heavy position
The copying of the information in DNA is straightforward because _____.
Each strand of a DNA molecule carries complementary information
Replication occurs at a _____.
Replication fork
The DNA double helix is separated into single strands by the enzyme _____.
DNA helicase
Short segments of RNA, called _____, are synthesized.
RNA primers
Newly-exposed, unreplicated DNA is protected by _____.
Binding proteins
The enzyme that synthesizes the short segments of RNA is called a _____.
Primase
New DNA is synthesized in the _____ direction.
5’ to 3’
The enzyme that catalyzes new DNA synthesis is _____.
DNA polymerase
Fragments of discontinuous DNA synthesis are called _____.
Okazaki fragments
Gaps in the sugar-phosphate backbone of DNA are closed by _____.
DNA ligase
What components are needed to perform PCR?
Target DNA, DNA primers, DNA nucleotides, and Taq1 Polymerase
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?
TTGTCAATG
Select next-generation sequencing techniques.
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
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?
DNA synthesis will occur until the polymerase reaches a thymine in the template strand, and then it will halt.
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?
DNA synthesis will occur until the polymerase reaches a thymine in the template strand, and then it will halt
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?
30%
