IB Biology Topic D1.3.4 Causes of Gene Mutation Revision Notes (SL/HL)

IB Biology Topic D1.3.4 Causes of Gene Mutation Revision Notes (SL/HL) | RevisionDojo

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Mutations Arise From Internal Errors And External Mutagens

A gene mutation is a change in the DNA sequence that can alter how a gene works.
Mutations arise in two broad ways:
1. Errors during DNA replication or repair.
2. Damage from external agents called mutagens.

Errors In DNA Replication

During replication, DNA polymerase occasionally adds the wrong nucleotide, giving a mismatched base pair.
Proofreading corrects most of these, but a small fraction escape and become permanent mutations.

Example

Instead of pairing adenine (A) with thymine (T), the polymerase might pair adenine with cytosine (C).

Errors In DNA Repair

DNA is constantly damaged by metabolic byproducts and environmental factors.
Repair systems such as base excision repair and nucleotide excision repair fix most of this damage.
If repair fails or introduces errors, the mutation remains.
1. For example, faulty repair of double-strand breaks can cause deletions, duplications, or chromosomal rearrangements.

Common Mistake

Not all mutations come from radiation or chemicals.
Many arise naturally from errors in DNA replication or repair.

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Mutations Arise From Internal Errors And External Mutagens

A gene mutation is a change in the DNA sequence that can alter how a gene works.
Mutations arise in two broad ways:
1. Errors during DNA replication or repair.
2. Damage from external agents called mutagens.

Errors In DNA Replication

During replication, DNA polymerase occasionally adds the wrong nucleotide, giving a mismatched base pair.
Proofreading corrects most of these, but a small fraction escape and become permanent mutations.

Example

Instead of pairing adenine (A) with thymine (T), the polymerase might pair adenine with cytosine (C).

Errors In DNA Repair

DNA is constantly damaged by metabolic byproducts and environmental factors.
Repair systems such as base excision repair and nucleotide excision repair fix most of this damage.
If repair fails or introduces errors, the mutation remains.
1. For example, faulty repair of double-strand breaks can cause deletions, duplications, or chromosomal rearrangements.

Common Mistake

Not all mutations come from radiation or chemicals.
Many arise naturally from errors in DNA replication or repair.

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

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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.

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A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D1.3.4: Causes of Gene Mutation Notes

Mutations Arise From Internal Errors And External Mutagens

Errors In DNA Replication

Errors In DNA Repair

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Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Mutations Arise From Internal Errors And External Mutagens

Errors In DNA Replication

Errors In DNA Repair

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics