Thermostable DNA Polymerases are Used in PCR Because They

Question

Thermostable DNA polymerases are used in PCR because they
A) bind DNA more efficiently than thermolabile DNA polymerases.
B) do not have a proof-reading activity.
C) are less expensive than E. coli DNA Pol III.
D) can survive at the high temperatures used to denature DNA.
E) are water soluble.

Accepted Answer

Thermostable DNA polymerases are used in PCR because they can survive at the high temperatures used to denature DNA (typically around 95°C). This allows for repeated cycles of denaturation, annealing, and extension of the DNA template during PCR without the need for frequent enzyme additions. Thermostable DNA polymerases also tend to have higher processivity (ability to incorporate multiple nucleotides without dissociation) and less error-prone replication than thermolabile DNA polymerases.