MBBS · Biochemistry

DNA replication and repair

DNA replication uses complementary base pairing to copy genetic information. Replication is semiconservative: daughter double helices typically contain one original and one newly synthesized strand.

Open interactive lesson & self-check ↗

DNA replication fork

Original conceptual SVG · scalable
Fork progression →Leading strandLagging fragments5′3′3′5′Original template strands are shown in blue

Concept schematic: each new strand grows 5′ to 3′. Leading is more continuous; lagging is synthesized in fragments.

Concept 01

Understand direction

DNA polymerases extend a nascent DNA strand in the 5′ to 3′ direction using a template read in the opposite direction.

Concept 02

Contrast strands

The leading strand is synthesized relatively continuously in the direction of fork progression; the lagging strand is synthesized in short Okazaki fragments.

Concept 03

Include quality control

Proofreading and DNA repair pathways reduce replication errors, but no process is absolutely error-free.

Education / safety note: The image is a conceptual fork. It omits primase, helicase complexes, topoisomerases, sliding clamps and repair machinery.

Reference and next reading

Explore the original curriculum and publisher-hosted resources for full-depth reading; this note is an original schematic introduction, not an exhaustive chapter.

Official / publisher source: NMC official CBME Curriculum 2024 and current regulations index ↗Official / publisher source: OpenStax Anatomy and Physiology 2e (read on publisher site) ↗Official / publisher source: PubMed ↗