🧬Understand DNA Replication Step by Step
Meet the enzymes of DNA replication one at a time, then draw a working replication fork from memory with leading and lagging strands correctly labeled.
Phase 1Meeting the Replication Fork
Watch helicase unzip DNA and meet the fork
Your cells copy 3 billion letters in eight hours
6 minYour cells copy 3 billion letters in eight hours
Helicase unzips the helix — and that's all it does
5 minHelicase unzips the helix — and that's all it does
Unzipping a twisted rope snarls the far end
6 minUnzipping a twisted rope snarls the far end
Bare single-stranded DNA is suicidal
6 minBare single-stranded DNA is suicidal
Phase 2One Enzyme, One Job
Name each enzyme and describe its one job
DNA polymerase can't start from nothing
6 minDNA polymerase can't start from nothing
The copyist reads 3' to 5', writes 5' to 3'
7 minThe copyist reads 3' to 5', writes 5' to 3'
One strand gets the easy life
6 minOne strand gets the easy life
The backwards strand is built in tiny chunks
7 minThe backwards strand is built in tiny chunks
Ligase welds the fragments into one strand
6 minLigase welds the fragments into one strand
Phase 3When Copying Goes Wrong
Link replication errors to mutation and cancer
A lab tech who double-checks every letter
7 minA lab tech who double-checks every letter
The error that slipped past proofreading
7 minThe error that slipped past proofreading
The typos that built you
7 minThe typos that built you
The fork that couldn't finish
8 minThe fork that couldn't finish
Phase 4Draw the Fork From Memory
Draw a replication fork from memory, fully labeled
Draw the replication fork from scratch, fully labeled
18 minDraw the replication fork from scratch, fully labeled
Frequently asked questions
- Why does the lagging strand exist if both strands are copied?
- This is covered in the “Understand DNA Replication Step by Step” learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
- What is the difference between helicase and topoisomerase?
- This is covered in the “Understand DNA Replication Step by Step” learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
- Why does DNA replication need an RNA primer at all?
- This is covered in the “Understand DNA Replication Step by Step” learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
- How do DNA polymerase proofreading errors become cancer?
- This is covered in the “Understand DNA Replication Step by Step” learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
- What are Okazaki fragments and why are they named after someone?
- This is covered in the “Understand DNA Replication Step by Step” learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
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