3.8.2.2 Regulation of Transcription and Translation Flashcards
What is epigenetics?
The study of markers on DNA
This allows us to understand what switches on genes
What is the epigenome?
All of the epigenetic markers in a cell or organism
What happens if a gene is not expressed?
No protein is made
What is chromatin?
The DNA molecule wrapped around histones
What determines whether the genes are expressed?
The interaction between DNA molecules and histones
What does the epigenome determine?
The shape of the DNA - histone complex
What is epigenetic silencing?
A tightly packed arrangement of the DNA-histone complex which makes a gene inactive
What is the addition of methyl groups called?
Methylation
What is the addition of acetyl groups called?
Acetylation
How do you express an addition or removal of methyl of acetyl groups?
Hyper- = more Hypo- = less
What are the environmental factors which affect the epigenome?
Stress and diet affect the epigenome which affects whether genes are expressed or not
What is the process of methylation?
Methyl group attaches to cytosine
This prevents the binding of transcriptional factors to the DNA
This attracts proteins to the gene which removes acetyl groups from the histones
Histones become more positively charged
DNA is negative
Association is stronger
This makes DNA become more tightly wrapped around the histone
This stops transcription because it is too tightly wound to reach the DNA
What does decreased acetylation cause?
A more condensed DNA histone complex
Chromatin: heterochromatin
No access for transcriptional factors
The gene becomes inactive
