DNA Replication
Start with the big picture
Replication produces daughter DNA molecules, each with one parental strand and one newly synthesized strand, during S phase. DNA polymerases extend from a free 3′-OH and synthesize DNA 5′→3′ while reading the template 3′→5′. Initiation and fork progression depend on coordinated unwinding, strand stabilization, primer synthesis, and polymerase activity. Because the two templates are oriented differently, one strand is made continuously and the other in Okazaki fragments that are joined by ligase. The lesson also introduces proofreading and mismatch repair, replication licensing and checkpoints, and telomerase’s role in extending chromosome ends. These principles provide context for understanding selected drugs and genetic disorders that affect replication or genome stability.
What you'll learn
- Describe the semiconservative outcome and cell-cycle timing of DNA replication.
- Explain DNA synthesis directionality and the requirement for a primer with a free 3′-OH.
- Distinguish leading- and lagging-strand synthesis at the replication fork.
- Identify key enzymes involved in initiation, elongation, primer removal, and fragment joining.
- Summarize how replication fidelity, telomeres, and clinical examples relate to DNA replication.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
