DNA Replication Enzymes

Key Enzymes

• DNA Polymerase III

  • Catalyzes the addition of new nucleotides.
  • Synthesizes DNA in the 5' to 3' direction.
  • Requires a 3' hydroxyl (O) group to begin synthesis.
  • Adds to the growing DNA strand.

• DNA G Primase

  • Provides the necessary 3' hydroxyl group for DNA Polymerase III.
  • Lays down an RNA primer of 10-12 nucleotides.
  • RNA primer is complementary to the DNA strand.
  • Does not require a primer to begin its function.

RNA vs. DNA Nucleotides

• RNA Nucleotides

  • Uracil (U) pairs with Adenine (A) instead of Thymine (T).
  • Ribonucleotides like GTP, GDP, GMP are associated with RNA.

• DNA Nucleotides

  • Deoxyribonucleotides like dGTP, dGDP, dGMP are associated with DNA.
  • Contain a deoxy group (deoxyribose sugar).

DNA Replication Process

• Leading Strand

  • Continuous replication in the 5' to 3' direction.

• Lagging Strand

  • Discontinuous replication (to be discussed further).

Additional Notes

• The function and interaction of these enzymes are crucial for DNA replication.
• DNA G Primase is essential for initializing the process by providing the RNA primer.
• The role of modified nucleotides in distinguishing between RNA and DNA is noteworthy and will be explored further in lectures.