A LITTLE LIGHTBULB MOMENT
Genetics and molecular biology
Semiconservative DNA replication
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Each daughter helix keeps one old strand like a borrowed shoe.
The idea behind the cue
DNA replication is semiconservative. Each daughter duplex contains one parental strand and one newly synthesized strand. The Meselson-Stahl experiment supported this model.
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Short & simple
Each daughter helix keeps one old strand like a borrowed shoe.
Acronym
PNM — Purple Narwhals Mumble.
Story
A zipper splits; each half becomes a guide for a new matching zipper half, so every finished molecule has one veteran strand and one rookie strand.
Connect the pieces
- P (Purple) → Parental: Each daughter DNA duplex keeps one original strand.
- N (Narwhals) → New: Each daughter duplex also gets one newly synthesized strand.
- M (Mumble) → Meselson-Stahl: Their experiment supported the semiconservative model of DNA replication.
- Purple · Parental: Each daughter DNA duplex keeps one original strand.
- Narwhals · New: Each daughter duplex also gets one newly synthesized strand.
- Mumble · Meselson-Stahl: Their experiment supported the semiconservative model of DNA replication.
Know the limits
Describes cellular DNA replication; conservative and dispersive models are not correct.
Further reading · OpenStax science textbooks ↗Check your understanding
After one round of DNA replication, what is true of each daughter molecule?
A. Two new strands
B. Random mixed patches of old and new strand segments
C. One old strand and one new strand
D. Two old strands
Reveal explanation
One old strand and one new strand
Semiconservative replication preserves one original strand in each daughter DNA molecule.