L3 - Epigenetic control of gene expression in eukaryotes Flashcards
Define genome
The entirety of the genetic sequences in an organism
Define proteome
The complete range of proteins the cell can produce
Define epigenome
A record of the chemical changes to the DNA and histone proteins of an organism. Can be passed down the generations
Define epigenetics
Epigenetics involves heritable changes in gene function, without changes to the base sequence of DNA
The chemicals which cover the DNA & histones are referred to as ____ and form part of the _______
Epigenetic tags, which form part of the epigenome
Tight winding =
Gene switched OFF, as RNA polymerase cannot access the genes
Loose winding =
Gene switched ON, as RNA polymerase can access the genes
Increased methylation of DNA =
Decreased transcription
Increased acetylation of histones =
Increased transcription
During DNA methylation, a methyl group is added to _____ __ of a _________ base.
During DNA methylation, a methyl group is added to CARBON 5 of a CYTOSINE base.
Where does DNA methylation occur?
Where a cytosine nucleotide is linked by a phosphodiester bond to a guanine nucleotide, creating a cytosine-guanine sequence which is represented as CpG (cytosine-phosphodiester bond-guanine)
Repeated CpG sequences are common in DNA near…
Gene promoters
The presence of repeated methylated CpG sequences prevents:
This inhibits ______
Therefore the affected gene cannot be transcribed, it is ______
Transcription factors from binding to the promoter
This inhibits RNA polymerase
It has now been ‘silenced’
Histone molecules contain side branches called ‘____’
Tails
What amino acid do the histone tails contain?
Lysine
