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
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 positive charge of histones > higher attraction between histones and the negative DNA –> DNA becomes more tightly wrapped –> RNA polymerase has less access to the DNA thus transcription is inhibited.
what is heterochromatin?
tightly packed DNA
what is euchromatin?
loosely packed DNA
why does tightly packed DNA reduce transcription?
makes the promoter regions less accessible to RNA polymerase
what is epigenetic inheritance?
inheritance of non-genetic info that can influence gene expression.
what is Phenotypic Plasticity?
changes in the gene expression due to the environment
give one example of phenotypic plasticity?
mice exposed to a high folic acid diet > increased methylation of specific genes related to coat colour > phenotype changed in offsprings
