10| DNA REPLICATION, 2-2

Question 1

In Eukaryotes, DNA synthesis at the ends of chromosomes (telomers) pose a special problem - over come by a unique RNA containing enzyme, called

Answer 1

telomerase

Question 2

The Taylor-Woods experiment

Used ____ method to analyze length and number of fragments.

Used a technique, _________, using an x-ray film to visualize fragments that have been radioactively labeled with 3H-Thymadine to point to locations of radioactive isotopes within the cell

Answer 2

Electrophorisis

Autoradiography

Question 3

Experiment included sedimentation equilibrium centrifugation and concluded the mode was semiconservative

Answer 3

The Nelson-Stahl experiment.

N14N14 –> light color
N14N15 –> intermediate color
N15N15 –> heavy color

semiconservative = 1 old and 1 new strand (parent and template)

Question 4

DNA synthesis in Eukaryotes, three aspects

Answer 4

1. unidirectional
2. multiple orgins
3. in the nucleus of the cell

Question 5

DNA synthesis in bacteria, fouraspects

Answer 5

1. single origin
2. bidirectional
3. also semiconservative
4. involves 5 polymers

Question 6

This is what you call the length of the DNA that is replicated after one initiation event at a single origin

Answer 6

replicon

Question 7

His experiment isolated an enzyme from E.coli that was able to direct DNA synthesis in a cell-free in vitro synthesis

Answer 7

Kronberg

Question 8

1. In Kronbergs experiment he used PI as the way in which nucleiotides are added to the growing chain and not PIII, why?
2. What were the two major requirements of this synthesis experiment?

Answer 8

PI is more stable and abundent

• His experiment isolated an enzyme from E.coli that was able to direct DNA synthesis in a cell-free in vitro synthesis
  2. all four dNTPs substrates and template DNA

Question 9

During 5-3 synthesis, the -OH from the template strand cleaves the triphosphate bond and adds a deoxyribose. PIII attatches the 5-3 ends and the two terminal phosphates left over are…

Answer 9

cleaved

Question 10

name seven issues to be resolved during DNA replication

Answer 10

1. unwinding of the helix
2. reducing increased coiling tension
3. synthesis of a primer for initiation to being
4. Discontinuous synthesis of the 2nd strand
5. removal of RNA primers and filling in of gaps
6. joining of gap filling DNA to the adjacent strand
7. proofreading

Question 11

Unwinding and the DNA helix

1. protein that bind to origin of replication and responsible for initial steps of unwinding
2. further opens and destabilizes helix

Answer 11

1. Dna A

2. Dna B

Question 12

Unwinding and the DNA helix, __________ is produced from unwinding

Answer 12

supercoiling

Question 13

Relieves supercoiling and makes single or double stranded cuts to do so

Answer 13

Gryase

Question 14

Orgins in yeast cells consist consensus sequences and are called

Answer 14

autonomously replicating sequences

Question 15

eukaryotic genomes consist mostly of _____coding DNA sequences

Answer 15

eukaryotic genomes consist mostly of non coding DNA sequences

Question 16

how did kronberg asses the fidelity of DNA PI in copying a DNA template?

Answer 16

He discovered an enzyme, PI that could carry out in vitro system.

then compared nitrogenous bases to the daughter strand.

Question 17

PI, PII or PIII

1. initiation of chain synthesis
2. 5-3 polymerization
3. 5-3 exonuclease activity
4. 3-5 exonuclease activity
5. Primary roles during replication

Answer 17

1. none
2. 5-3 polymerization;all 3
3. 5-3 exonuclease activity; PI only
4. 3-5 exonuclease activity; all 3
5. PI = primer cleaving, repair and gap filling

pII = repair

PIII = polymerization and proofreading