Biology Practice Flashcards

  • DNA Replication: Semi-conservative process; each original strand serves as a template:

    • Base-Pairing:

    • Adenine (A) pairs with Thymine (T)

    • Guanine (G) pairs with Cytosine (C)

    • Structure:

    • Double helix, strands are antiparallel (one runs 5' to 3', the other 3' to 5').

    • Leading strand (continuously replicated), Lagging strand (replicated in Okazaki fragments).

  • Replication Process:

    1. DNA Helicase: Unzips DNA by breaking hydrogen bonds, forming a replication fork.

    2. SSBPs: Keep strands apart.

    3. Topoisomerase: Relieves tension from unwinding.

    4. RNA Primase: Adds RNA primer to start replication.

    5. DNA Polymerase III: Adds nucleotides in 5' to 3' direction, stays attached via Sliding Clamp.

    6. DNA Polymerase I: Proofreads and replaces RNA primers with DNA.

    7. DNA Ligase: Joins Okazaki fragments on the lagging strand.

  • Key Enzyme Order: DNA Polymerase III (first), DNA Polymerase I (follows).