Student Center
|
Instructor Center
|
Information Center
|
Home
Web Links
Lecture PowerPoints
Image PowerPoints
Choose a Chapter
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Chapter 13
Chapter 14
Chapter 15
Chapter 16
Chapter 17
Chapter 18
Chapter 19
Chapter 20
Chapter 21
Chapter 22
Chapter 23
Chapter 24
Action of DNA Gyrase
Bidirectional DNA Replication
Direct Repair
DNA Replication (E. coli)
DNA Replication Fork
How Nucleotides Ar...
Meselson and Stahl Experiment
Methyl-directed Mi...
Nucleotide Excision Repair
Proofreading Funct...
Rolling Circle Mec...
Thymine Dimers For...
Feedback
Help Center
Molecular Biology, 4/e
Robert F. Weaver
DNA Replication I: Basic Mechanism and Enzymology
Proofreading Function of DNA Polymerase
How does DNA polymerase use the structure of DNA to catch errors?
DNA polymerase moves along a single strand of DNA, building the complementary strand as it goes. The two stranded molecule passes through the DNA polymerase molecule after synthesis is complete. If the wrong base is inserted then the bond is unstable. Because the double strand is passing through the DNA polymerase the missing base can be detected and replaced. The replacement is done by a different part of the enzyme. If DNA polymerase did use single stranded DNA as a template and the completed double strand did not continue to interact with the enzyme after synthesis then the number of errors in DNA replication would be much higher.
View the animation below, then complete the quiz to test your knowledge of the concept.
1
The proofreading function of DNA polymerase reduces the error rate from about one in a million basepairs to about one in a ________ basepairs.
A)
hundred thousand
B)
ten thousand
C)
thousand
D)
ten million
E)
hundred million
2
DNA polymerases use their ________ activity to remove a mismatched basepair.
A)
3’ -> 5’ exonuclease
B)
5’ -> 3’ exonuclease
C)
RNase
D)
protease
E)
mismatchase
3
Proofreading by DNA polymerase involves the removal of
A)
only the mismatched base on the old strand of DNA.
B)
only the mismatched base on the newly-synthesized strand of DNA.
C)
the mismatched basepair on both strands of DNA.
D)
several bases on the newly-synthesized strand of DNA.
E)
several bases on the old strand of DNA.
4
Improper base-pairing during DNA replication causes a pause in chain elongation.
A)
True
B)
False
5
Following base removal, DNA polymerase can add nucleotides in the 5’ to 3’ direction.
A)
True
B)
False
2008 McGraw-Hill Higher Education
Any use is subject to the
Terms of Use
and
Privacy Policy
.
McGraw-Hill Higher Education
is one of the many fine businesses of
The McGraw-Hill Companies
.