Chapter 10: DNA Synthesis Flashcards
A method of replication where each replicated DNA molecule would consist of one “old” and one “new” strand.
Semiconservative Replication of DNA
A method of replication where two newly created strands then come together, and the parental strands reassociate.
Conservative Replication
A method of replication where the parental strands are dispersed into two new double helices following replication.
Dispersive Replication
True or False. Conservative Replication is the most complex of the three possibilities and is therefore considered to be least likely to occur
False. Dispersive Replication
Samples are forced by centrifugation through a density gradient of a heavy metal salt, such as cesium chloride.
Sedimentation equilibrium centrifugation (Meselson-Stahl Experiment) - an experiment providing strong evidence that semiconservative replication is the mode used by bacterial cells to produce new DNA molecules.
Is a common technique that, when applied cytologically, pinpoints the location of a radioisotope in a cell.
Autoradiography
At each point along the chromosome where replication is occurring, the strands of the helix are unwound, creating what structure?
Replication Fork
Refers to the length of DNA that is replicated following one initiation event at a single origin.
Replicon
The region in E. coli DNA where replication is initiated
oriC
True or False. DNA synthesis in bacteriophages and bacteria originates at a single point, the entire chromosome constitutes one replicon.
True
True or False. Replication in bacteria and viruses is bidirectional, moving away from oriC in both directions
True
Terminal region in a replicating bacterial or viral DNA.
ter
A single polypeptide containing 928 amino acids initially isolated from E. coli that is able to direct DNA synthesis in a cell-free (in vitro) system.
DNA polymerase I
Two major requirements for in vitro DNA synthesis under the direction of DNA polymerase I:
- All four deoxyribonucleoside triphosphates (dNTPs)
2. template DNA
True or False. As the two terminal phosphates of the deoxyribonucleoside triphosphate precursor are cleaved during DNA synthesis, the remaining phosphate attached to the 5′-carbon is covalently linked to the 3′-OH group of the deoxyribose to which it is added.
True
A mutant strain of E. coli that was deficient in polymerase I activity.
polA1
An existing RNA strand that can be elongated by polymerases I, II, and III.
Primer
True or False. Polymerase I, II, and III can initiate chain synthesis.
False. They all can’t.
True or False. Polymerase I, II, and III exhibit 5’-3’ polymerization.
True
True or False. Polymerase I, II, and III do not exhibit 3′ to 5′ exonuclease activity.
False. They all exhibit 3′ to 5′ exonuclease activity.
True or False. Only Polymerase I exhibit 5’-3’ exonuclease activity.
True
Encoded by a gene whose transcription is activated by disruption of DNA synthesis at the replication fork.
Polymerase II
Are involved in various aspects of repair of DNA that has been damaged by external forces, such as ultraviolet light.
DNA polymerase II, IV and V
The active form of the DNA Polymerase III.
Holoenzyme