regulation of transcription and translation Flashcards
how can transcription of target genes be inhibited or stimulated
specific transcription factors move from cyctoplasm to nucleus
what does controlling gene expression make cells
specilaised
what do transcritpion factors do
move from cyctoplasm to nucleus
bind to DNA in promoter region/operator region and therefore initiates/inhibits transcription therefore trnalsation of the protein
if TF arent present
genes turned off
role of oestrogen
oestorgen enters cytoplasm through pbl as lipid soluble
binds to receptor site on TF
changes tert structure of TF
inhibitor molecule from surface of TF released
TF now complimentary to and can bind to promoter region of DNA , itiated transcription
epigeneitcs
environmnetal changes that cause heritbale chmages in gene function without changing DNA base sequnce
epigentic contorlled mediated by chemical tags: epigenome
effect of increased methylation of DNA
methyl groups added to DNA at cytosine bases
attracts proteins that condense chromatin
chromatin condenses
prevents TF binding to promoter region
inhibits transcription, RNA polymerase cant bind
chromatin
DNA histone complex
effect of decreased acetlyation
histones become more + charged
attract phosphate groups on DNA
chromatin condenses
transcription factors and RNA polymerase cant bind
how can epigenetic lead to cancer
increased metyhlation and decreased acetylation of tumour supressor genes
decreased methlation and increased acetylation of proto- onocogens
how can epigenetics stop cancer
increased methaltion and decreased acetylation of proto-oncogens
decreased ethylation and increased acetlyation of tumour supressor genes
how can trwatment stop diseases
drugs can be given to prevent changes
RNA interefrnce
transaltion form mRNA of target genes can be inhibited by RNAi,
mRNA destroyed before transaltion
two types: siRNA
miRNA
siRNA
enzyme cuts large double stranded molecules of RNA into siRNA (double stranded)
one strand combines with enzyme
siRNA molecule guides enzyme to mRNA molecule by pairing up its complimentary bases with section of the mRNA
enzyme cuts the mRNA into smaller sections
mRNA can no longer be translated
gene not expressed
what is siRNA
specific, only binds to one type on mRNA
