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Epigenetics - Coggle Diagram
Epigenetics
Definition
- study of heritable modifications of genome
(changes in gene expression)
- that do not involve changes in DNA base sequence
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DNA Methylation
- chemical group methyl (CH3)
added to nucleotide base CYTOSINE
(when followed by G base)
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- many CpG sequences grouped
together on coding strand
forms CpG islands
- if critical no. of islands methylated
- DNA switched off in region
- prevents attachment of RNA polymerase
- transcription cannot take place
- Methylated DNA is switch at
the start of the gene
(rather than coding sequence)
-
when methylated cell undergoes mitosis
- methylated gene passed from cell to cell
- and onto subsequent generations of individuals
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Histone Modification
- DNA is wrapped around
bundles of 8 histone proteins
- histones be modified by adding
chemical groups to them
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-
complex
- different groups
- attach to different areas
- each having a different effect
examples
- some make DNA more accessible to transcription
- some prevent transcriptions
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Plants
plants adapted to grow in dim environments
- increased gene expression in genes = harvesting light
- decreased gene expression in genes = reproduction
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