IB Biology Topic D1.1.8 DNA Primase, DNA Polymerase I, DNA Polymerase III and DNA Ligase in Replication Revision Notes (HL)

IB Biology Topic D1.1.8 DNA Primase, DNA Polymerase I, DNA Polymerase III and DNA Ligase in Replication Revision Notes (HL) | RevisionDojo

Written by official IB examiners

Four Enzymes Work Together to Copy DNA

DNA replication is a highly coordinated process, and each enzyme has a specific role.

Note

This section focuses on the prokaryotic system, where replication is simpler but follows the same principles as in eukaryotes.

DNA Primase: Laying the Foundation

Definition

Primase

Primase is an enzyme that synthesizes a short RNA primer to provide a starting point for DNA polymerase III during replication.

DNA polymerases cannot start a new strand on their own.
They need a starting point, a short segment of RNA called a primer.

Key Functions of DNA Primase

Synthesizes RNA primers
1. It makes a short RNA primer (about 10 nucleotides) on the template strand.
Provides a 3′-OH group
1. The primer gives a free 3′-OH group, which DNA polymerase III needs to start adding DNA nucleotides.
Adds primers on the lagging strand
1. It adds a new primer for each Okazaki fragment.

Tip

DNA polymerases can only extend a strand, not start one from scratch, which is why primase is essential.

DNA Polymerase III: The Main Builder

DNA polymerase III is the workhorse of replication, building most of the new DNA strand.
It is the main enzyme that synthesizes new DNA in prokaryotes.

Key Functions of DNA Polymerase III

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Unlock the rest of this chapter with a free account

Four Enzymes Work Together to Copy DNA

DNA replication is a highly coordinated process, and each enzyme has a specific role.

Note

This section focuses on the prokaryotic system, where replication is simpler but follows the same principles as in eukaryotes.

DNA Primase: Laying the Foundation

Definition

Primase

Primase is an enzyme that synthesizes a short RNA primer to provide a starting point for DNA polymerase III during replication.

DNA polymerases cannot start a new strand on their own.
They need a starting point, a short segment of RNA called a primer.

Key Functions of DNA Primase

Synthesizes RNA primers
1. It makes a short RNA primer (about 10 nucleotides) on the template strand.
Provides a 3′-OH group
1. The primer gives a free 3′-OH group, which DNA polymerase III needs to start adding DNA nucleotides.
Adds primers on the lagging strand
1. It adds a new primer for each Okazaki fragment.

Tip

DNA polymerases can only extend a strand, not start one from scratch, which is why primase is essential.

DNA Polymerase III: The Main Builder

DNA polymerase III is the workhorse of replication, building most of the new DNA strand.
It is the main enzyme that synthesizes new DNA in prokaryotes.

Key Functions of DNA Polymerase III

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D1.1.8: DNA Primase, DNA Polymerase I, DNA Polymerase III and DNA Ligase in Replication Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Four Enzymes Work Together to Copy DNA

DNA Primase: Laying the Foundation

Key Functions of DNA Primase

DNA Polymerase III: The Main Builder

Key Functions of DNA Polymerase III

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Four Enzymes Work Together to Copy DNA

DNA Primase: Laying the Foundation

Key Functions of DNA Primase

DNA Polymerase III: The Main Builder

Key Functions of DNA Polymerase III

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account