DNA replication

4 articles
1 video
When you make a copy of something, how perfect does the copy need to be? If that something is your DNA, the answer is, pretty perfect! Errors during DNA copying can lead to cancer and other health conditions. Learn how cells use a group of different enzymes to accurately copy their DNA, and how they detect and repair copying errors and DNA damage.

Mode of DNA replication: Meselson-Stahl experiment

ARTICLE
A key historical experiment that demonstrated the basic mechanism of DNA replication. Semi-conservative, conservative, and dispersive models of replication. Techniques including isotopic labeling and density gradient centrifugation.

DNA replication and RNA transcription and translation

VIDEO 15:24 minutes
What genes and alleles really are at the molecular level. A gene as a stretch of DNA on a chromosome, and alleles as different versions (sequence variants) of a gene.

Molecular mechanism of DNA replication

ARTICLE
Molecular details of DNA replication. Roles of DNA polymerase III, DNA polymerase I, helicase, ligase, primase, topoisomerase, and single-stranded binding proteins. Leading and lagging strands and Okazaki fragments. Trombone model of DNA ...

DNA proofreading and repair

ARTICLE
Mechanisms to correct errors during DNA replication and to repair DNA damage sustained over the cell's lifetime. Covers proofreading polymerases, mismatch repair, and various forms of DNA damage repair.

Telomeres and telomerase

ARTICLE
Telomeres are protective "caps" found on the tips of eukaryotic chromosomes. Learn why telomeres shorten in each round of DNA replication, and how some cells lengthen their telomeres using the enzyme telomerase.