If a mutation prevented synthesis of the beta subunit of DNA pol III, which would be most affected?

Question

A.  DNA unwinding
B.  formation of RNA primers
C.  formation of the replication fork
D.  processivity
E.  removal of RNA primers

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain?

Gather Content
· What do you already know about DNA polymerase?
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  processivity

Clarify Question
· What is the key concept addressed by the question?
    o This question addresses the function of DNA polymerase.
· What type of thinking is required?
    o You need to Analyze the information given, using logic, to dissect the problem and determine the answer.
· What key words does the question contain?
    o DNA pol III is the abbreviation for DNA Polymerase III. One particular protein subunit is the beta (b) subunit.

Gather Content
· What do you already know about DNA polymerase?
    o DNA polymerase III is responsible for the bulk of DNA synthesis in E. coli.
    o The beta subunit is known as a “sliding clamp”. It forms a ring that can slide along the DNA.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
    o DNA pol III is a DNA polymerase – it synthesizes DNA, not RNA. So it is unrelated to the formation of RNA primers.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
    o The beta subunit forms a ring that slides along the DNA. Its role is to keep the polymerase attached to the DNA. As long as the polymerase stays on the DNA, it can continue to synthesize DNA on the leading strand.
    o The continuous synthesis of DNA is called processivity. Thus, if the beta subunit sliding clamp was missing, the polymerase would fall off the DNA and lack processivity.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
    o This question required you to Analyze the information given, using logic, to dissect the problem and determine the answer.
    o Did you remember that the beta subunit is shaped like a ring – a sliding clamp?
    o Did you recognize that if the beta subunit was missing, the polymerase would fall off the DNA more often?
    o Did you remember that the quality of continuing to synthesize DNA is called processivity?