Taq DNA polymerase, which is commonly used for PCR, is a thermostable DNA polyme

Question

Taq DNA polymerase, which is commonly used for PCR, is a thermostable DNA polymerase that lacks proofreading activity. Other DNA polymerases, such as Vent, have proofreading activity. What advantages are there to using a DNA polymerase for PCR that has proofreading activity? Although some DNA polymerases am more accurate than others, all DNA polymerases used in PCR introduce errors at a low rate. Why are errors introduced in the first few cycles of a PCR amplification more problematic than errors introduced in the last few cycles of the PCR amplification?

Explanation / Answer

a)

Advantages

1. Proofreading Taq Polymerase (PTP) generated PCR fragments will have fewer errors than Taq-generated PCR inserts.

2. Mismatched ends extended poorly and may cause early termination of extension. Thus, PTP will amplify long sequences successfully upto 25 kb than Taq polymerase

3. Unlike Taq DNA polymerase which creates poly A overhang,  PTP create blunt-ended PCR products, which are ideal for cloning into blunt-ended vectors.

4. Proofreading is crucial for applications such as mutagenesis, when it’s important to know the exact sequence of your PCR product.

b)

During each cycle PCR copies and multiplies the errors committed in the earlier cycles; as a result, errors keep on accumulating during PCR. Thus, it is very important that less errors are introduced during first few cycles of PCR.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.