Jack Westin MCAT Podcast MCAT DNA Replication Explained: Semi-Conservative Copying, Okazaki Fragments, & Mutation Repair
Oct 21, 2025
This discussion dives into the intricate world of DNA replication, highlighting its semi-conservative nature where each new double helix contains one old and one new strand. Key enzymes like helicase and DNA polymerase are introduced as they unwound and synthesize DNA. The hosts elaborate on Okazaki fragments, mutation types, and various repair mechanisms such as nucleotide excision repair. They also explore the implications of mutations on cancer and the revolutionary potential of CRISPR in gene editing. It's a captivating journey through genetics and cell biology!
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Semi-Conservative Replication Explained
- DNA replication is semi-conservative: each daughter helix contains one old and one new strand.
- Complementarity ensures both daughters are identical despite each getting only one original strand.
Unwinding Requires Multiple Enzymes
- Helicase unwinds the helix while SSB proteins stabilize separated strands to prevent reannealing.
- Topoisomerase relieves supercoiling by cutting and rejoining DNA to prevent tension and breaks.
Always Start With An RNA Primer
- Use an RNA primer before DNA polymerase III can synthesize a new strand because DNA polymerase cannot start de novo.
- Always synthesize DNA 5'→3', so polymerase reads the template 3'→5'.