DNA polymerase III is the main DNA-synthesizing enzyme in bacteria. Describe how it carries out its role of elongating a strand of DNA.

Verified step by step guidance

1. DNA polymerase III adds nucleotides to the 3' end of a growing DNA strand, using the existing strand as a template.
2. The enzyme requires a primer with a free 3'-OH group to initiate DNA synthesis.
3. DNA polymerase III reads the template strand in the 3' to 5' direction and synthesizes the new strand in the 5' to 3' direction.
4. The enzyme ensures high fidelity in DNA replication by proofreading each nucleotide it adds, using its 3' to 5' exonuclease activity to remove incorrectly paired bases.
5. DNA polymerase III works in conjunction with other proteins in the replisome complex to efficiently replicate the bacterial genome.

Key Concepts

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA, ensuring that each daughter cell receives an identical copy. This process involves unwinding the double helix and synthesizing new strands complementary to the original templates. DNA polymerase III plays a crucial role in this process by adding nucleotides to the growing DNA strand during elongation.

Enzyme Function

Enzymes are biological catalysts that speed up chemical reactions in cells. DNA polymerase III functions by catalyzing the formation of phosphodiester bonds between nucleotides, which are the building blocks of DNA. This enzyme requires a primer to initiate synthesis and can only add nucleotides to the 3' end of a growing DNA strand, ensuring the correct directionality of elongation.

Leading and Lagging Strands

During DNA replication, the two strands of the double helix are oriented in opposite directions, leading to the formation of leading and lagging strands. The leading strand is synthesized continuously in the direction of the replication fork, while the lagging strand is synthesized in short segments called Okazaki fragments, which are later joined together. DNA polymerase III is responsible for synthesizing both strands, but its activity differs based on the strand's orientation.