Gene expression Flashcards
define gene expression
the process by which genetic information is used to produce RNA and proteins.
what are the two main stages of gene expression?
transcription
translation
what are the two types of transcription factors?
activators
repressors
what is the role of activators?
encourage binding of RNA polymerase to promoters
what is the role of repressors?
blocks binding between RNA polymerase to promoters
Where are enhancers situated?
far away from the gene
what is the role of enhancers?
activator proteins bind to enhancers to form a complex which binds RNA polymerase to promoters
what are operons?
genes with a shared promoter
which enzymes breaks down mRNA?
nucleases
what factors affect the life span of mRNA?
whether it has a 5’ end cap and 3’ end poly tail (makes it more stable)
stabilising proteins
level of nucleases
stress factors - heat and toxins
what is DNA methylation?
addition of methyl group to cytosine in the promoter region
what is histone acetylation?
The addition of an acetyl group (CH₃COO⁻) to the amino acids in histone tails.
what are the consequences of histone acetylation?
decreases overall charge of histones –> less electrostatic attraction between histones and DNA –> DNA becomes less tightly wrapped –> increases transcription
what is histone methylation?
the addition of a methyl group to histone tails
what are the consequences of histone methylation?
increases overall charge of histones –> higher electrostatic attraction between histones and DNA –> DNA becomes more tightly wrapped –> decreases transcription
