Multiple Choice
In agarose gel electrophoresis, the separation (analysis) of DNA fragments is primarily based on which property?
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18. Molecular Genetic Tools
Methods for Analyzing DNA
Multiple Choice
In the polymerase chain reaction (PCR), which enzyme synthesizes (builds) the new DNA strands during the extension step?
A
DNA ligase
B
A thermostable DNA polymerase (e.g., Taq DNA polymerase)
C
RNA polymerase
D
A restriction endonuclease (restriction enzyme)
Verified step by step guidance1
Understand the role of each enzyme listed in the context of DNA processes: DNA ligase joins DNA fragments, RNA polymerase synthesizes RNA from a DNA template, and restriction endonucleases cut DNA at specific sequences.
Recall the steps of PCR: denaturation (separating DNA strands), annealing (binding primers), and extension (synthesizing new DNA strands).
Identify which enzyme is responsible for synthesizing new DNA strands during the extension step of PCR.
Recognize that the enzyme must be thermostable to withstand the high temperatures used in PCR cycles.
Conclude that the enzyme synthesizing new DNA strands during PCR extension is a thermostable DNA polymerase, such as Taq DNA polymerase.
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