Question

Which exonuclease or exonucleases of DNA polymerase cause the release of 32P from DNA? 5'-3' exonuclease 3' 5' exonuclease Which exonuclease activity of DNA polymerase is inhibited by deoxyribonucleotide triphosphates (dNTPs)?

3'-5' exonuclease 5' 3' exonuclease What is the effect of pyrophosphate on the 3'-5' exonuclease activity of DNA polymerase?

Answer 1

DNA polymerase I is the exonuclease that causes the release of 32P from DNA, while deoxyribonucleotide triphosphates (dNTPs) inhibit the 3' -> 5' exonuclease activity of DNA polymerase. Pyrophosphate stimulates and enhances the 3' -> 5' exonuclease activity of DNA polymerase by acting as a competitive inhibitor.

Step-by-step explanation:

DNA polymerase I is the exonuclease that causes the release of 32P from DNA. This enzyme possess the 5' -> 3' exonuclease activity, which removes the RNA primer at the terminal end. On the other hand, the 3' -> 5' exonuclease activity of DNA polymerase is inhibited by deoxyribonucleotide triphosphates (dNTPs).

The effect of pyrophosphate on the 3' -> 5' exonuclease activity of DNA polymerase is that it stimulates and enhances this activity. Pyrophosphate functions as a competitive inhibitor of the exonuclease activity, preventing the hydrolysis of the phosphodiester bond and allowing DNA synthesis to continue.

Answer 2

The 5'-3' exonuclease activity of DNA polymerase I is involved in primer removal, while the 3'-5' exonuclease activity is responsible for proofreading and is inhibited by both deoxyribonucleotide triphosphates and pyrophosphate.

Step-by-step explanation:

The exonucleases of DNA polymerase are responsible for removing incorrect nucleotides. The 5'-3' exonuclease activity, which is associated with DNA polymerase I in prokaryotes, is known for removing RNA primer at the terminal end of the DNA strand. On the other hand, the 3'-5' exonuclease activity of DNA polymerase plays a crucial role in the proofreading function during DNA replication. The latter's exonuclease activity is inhibited by the presence of deoxyribonucleotide triphosphates (dNTPs), which are the building blocks of DNA synthesis.

When the 3'-5' exonuclease activity is functioning, incorrect nucleotides may be removed. However, the presence of pyrophosphate, the byproduct of the polymerization reaction where dNTPs are joined to form the growing DNA strand, can inhibit this proofreading function.