IB Biology Topic D2.2.6 Methylation of the Promoter and Histones in Nucleosomes as Examples of Epigenetic Tags Revision Notes (HL)

IB Biology Topic D2.2.6 Methylation of the Promoter and Histones in Nucleosomes as Examples of Epigenetic Tags Revision Notes (HL) | RevisionDojo

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Epigenetic Tags Control Gene Expression by Methylating Promoters and Histones

Gene expression depends not just on the DNA sequence but on how that sequence is regulated.
This regulation is influenced by epigenetic tags, chemical modifications that alter gene activity without changing the DNA sequence itself.
The two key examples are methylation of the promoter and modification of histones in nucleosomes.

Methylation of a Promoter Represses Transcription of Its Gene

Definition

DNA methylation

DNA methylation involves the addition of a methyl group (–CH₃) to a cytosine base in DNA.

DNA methylation adds a methyl group to cytosine bases in the DNA.
It often occurs in CpG islands, regions rich in cytosine-guanine pairs that are frequently found in promoters.

A methylated promoter represses transcription in two ways.

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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 ullamco laboris.
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Epigenetic Tags Control Gene Expression by Methylating Promoters and Histones

Gene expression depends not just on the DNA sequence but on how that sequence is regulated.
This regulation is influenced by epigenetic tags, chemical modifications that alter gene activity without changing the DNA sequence itself.
The two key examples are methylation of the promoter and modification of histones in nucleosomes.

Methylation of a Promoter Represses Transcription of Its Gene

Definition

DNA methylation

DNA methylation involves the addition of a methyl group (–CH₃) to a cytosine base in DNA.

DNA methylation adds a methyl group to cytosine bases in the DNA.
It often occurs in CpG islands, regions rich in cytosine-guanine pairs that are frequently found in promoters.

A methylated promoter represses transcription in two ways.

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 D2.2.6: Methylation of the Promoter and Histones in Nucleosomes as Examples of Epigenetic Tags Notes

Epigenetic Tags Control Gene Expression by Methylating Promoters and Histones

Methylation of a Promoter Represses Transcription of Its Gene

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

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Epigenetic Tags Control Gene Expression by Methylating Promoters and Histones

Methylation of a Promoter Represses Transcription of Its Gene

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