IB Biology Topic D2.2.7: Epigenetic Inheritance Through Heritable Changes to Gene Expression Notes

Epigenetic Tags Are Heritable, So Patterns of Gene Expression Can Be Passed On

Genes are like books in a library, and epigenetic tags decide which are open to read and which are locked away.

These tags change gene expression without altering the DNA sequence.

The key point of this topic is that these tags are heritable, so a pattern of gene expression can be copied to new cells and, in limited cases, to offspring.

Definition

Epigenetic tag

An epigenetic tag is a chemical modification to DNA or histone proteins that regulates gene expression without altering the underlying DNA sequence.

Note

Two tag types set gene expression: DNA methylation of cytosine bases tends to silence genes.
Histone modifications such as acetylation loosen or tighten chromatin to activate or repress genes.
The detailed mechanism of these tags belongs to D2.2.6, so here the focus is how they are inherited.

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Definition

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IB Biology Topic D2.2.7: Epigenetic Inheritance Through Heritable Changes to Gene Expression Notes

Epigenetic Tags Are Heritable, So Patterns of Gene Expression Can Be Passed On

Mitosis Copies Epigenetic Tags So Specialised Cells Keep Their Identity

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Epigenetic Tags Are Heritable, So Patterns of Gene Expression Can Be Passed On

Mitosis Copies Epigenetic Tags So Specialised Cells Keep Their Identity

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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 D2.2.7: Epigenetic Inheritance Through Heritable Changes to Gene Expression Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Epigenetic Tags Are Heritable, So Patterns of Gene Expression Can Be Passed On

Mitosis Copies Epigenetic Tags So Specialised Cells Keep Their Identity

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

Epigenetic Tags Are Heritable, So Patterns of Gene Expression Can Be Passed On

Mitosis Copies Epigenetic Tags So Specialised Cells Keep Their Identity

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