Updated: 5/6/2017

DNA Replication

0%
Topic
Review Topic
0
0
N/A
N/A
Questions
5 5
0
0
0%
0%
Evidence
1 1
0
0
 
Overview 
  • Function
    • replicate cell genome in a manner that is highly accurate
  • Process 
    • DNA melted to expose single strand to expose origin of replication
    • single stranded binding proteins (SSBs) bind and stabilize melted DNA
    • RNA primer added in 5' → 3' direction by primase
    • DNA polymerase adds adds nucleotides in a 5' → 3'
      • DNA polymerase III in prokaryotes
      • DNA polymerase α and δ in eukaryotes
      • can edit mistakes with a 3' → 5' exonuclease activity
      • adds continuously on the leading strand
      • adds discontinuous Okazaki fragments on the lagging strand because it must synthesize in a 5' → 3' direction
    • DNA gyrase (topoisomerase II) breaks the DNA to prevent coiling
    • RNA primer removed
      • by RNAase H in eukaryotes and filled by a DNA polymerase
      • by DNA polymerase I in prokaryotes and can fill simultaneously
    • DNA ligase seals the nick between fragments
  • Differences between prokaryotes eukaryotes
    • prokaryotes
      • single origin of replication
    • eukaryotes
      • multiple origins of replication
  • Clinical importance
    • antibiotics
      • quinolones, fluoroquinolones block bacterial topoisomerase
        • used to treat aerobic gram negatives in UTIs and gonorrhea
        • e.g. drugs ending in -floxacin
    • cancer chemotherapy
      • etoposide, teniposide block eukaryotic topoisomerase
 

Please rate topic.

Average 4.5 of 13 Ratings

Questions (5)

(M1.BC.17.4707) A 55-year-old male with a 60 pack-year smoking history presents to his oncologist for ongoing management of his recently diagnosed small cell lung cancer. His oncologist discusses several options and decides to start the chemotherapeutic medication, etoposide. The patient is warned that one side effect of this drug is myelosuppression so he should be vigilant for development of any infectious symptoms. The beneficial effect of this drug in treating cancer is most likely due to which of the following effects? Tested Concept

QID: 108444
1

Alkylation of DNA

18%

(43/242)

2

Crosslinking of DNA

13%

(32/242)

3

DNA intercalation

13%

(32/242)

4

Inhibition of supercoil relaxation

41%

(99/242)

5

Stabilization of microtubules

11%

(26/242)

M 1 C

Select Answer to see Preferred Response

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.BC.15.73) A mutant stem cell was created by using an inducible RNAi system, such that when doxycycline is added, the siRNA targeting DNA helicase is expressed, effectively knocking down the gene for DNA helicase. Which of the following will occur during DNA replication? Tested Concept

QID: 106556
1

DNA is not unwound

74%

(164/223)

2

DNA supercoiling is not relieved

13%

(30/223)

3

The two melted DNA strands reanneal

5%

(11/223)

4

The RNA primer is not created

2%

(4/223)

5

Newly synthesized DNA fragments are not ligated

5%

(11/223)

M 1 E

Select Answer to see Preferred Response

(M1.BC.13.11) Although nucleotide addition during DNA replication in prokaryotes proceeds approximately 20-times faster than in eukaryotes, why can much larger amounts of DNA be replicated in eukaryotes in a time-effective manner? Tested Concept

QID: 100076
1

Eukaryotes have less genetic material to transcribe

0%

(0/27)

2

Eukaryotes have fewer polymerase types

4%

(1/27)

3

Eukaryotes have helicase which can more easily unwind DNA strands

7%

(2/27)

4

Eukaryotes have multiple origins of replication

89%

(24/27)

5

Eukaryotes do not have exons

0%

(0/27)

M 1 E

Select Answer to see Preferred Response

Evidence (1)
Topic COMMENTS (37)
Private Note