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DNA

Replication Through Dance

Isabella, JT, & Lidia

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Assumptions &

Acknowledgements

This lesson assumes some background knowledge of biology.
For digestibility, this lesson omits some key details. This lesson should be supplemented with a follow up lecture including the omitted details

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DNA Structure Review

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DNA is a double helix

Two complementary strands are weakly bonded to each other via hydrogen bonds

Antiparallel: one strand goes 5’->3’, the other 3’->5’

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Introducing the Proteins

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Helicase

Breaks hydrogen bonds between DNA strands, effectively “unzipping” them

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DNA Polymerase

Builds growing DNA strand by binding free nucleotides to complementary strand in the 5’->3’ direction

Problem: DNA polymerase can’t start the strand, only build to an ongoing one

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Primase

Places small initial strand of RNA to give DNA polymerase a place to launch off of

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Ligase

Binds fragments together to make DNA strand continuous

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Steps

Helicase Unwinds

01

Primer Lays Primers

02

Polymerase Builds

03

Ligase Joins Fragments

04

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01: Helicase “unzips” DNA strands

SSB proteins bind to the strands, keeping them from coming back together

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Can we start copying DNA now?

NO!

Remember, DNA polymerase can’t create new strands, only build ongoing ones!

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02: Primase lays RNA primers to give polymerase a start point

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03: Polymerase adds nucleotides

(Adenine pairs with Thymine, Cytosine with Guanine)

Primers are removed as DNA polymerase builds

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Leading and Lagging Strand

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04: Ligase Joins Fragment

The helix has rejoined and is duplicated!!

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Time To Dance!

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Image Credits

Molnar, C., & Gair, J. (2015). Concepts of Biology: 1st Canadian Edition. BCcampus.

Images from Pressbooks: https://pressbooks.bccampus.ca

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Thank You!

Lidia Prokopovych

JT Toler

Isabella Quan