conrtol of expression 2 Flashcards
what do transacting TFs bind to?
cis-acting DNA sequences in chromatin
what is chromatin?
complex of DNA and proteins
what are the building blocks of chromatin?
necleosome (2 turns of DNA wrpped round histone)
what is problem with chromatin
makes is difficult for Tfs to find target genes
what are solutions for TFs finding target genes?
covalent modification of DNA an histone (flags)
chromatin remodelling factors
how are nucelosomes fixed into position?
by linker histone H1
what does chromatin remodelling factor do?
displace linker histone and core histones from DNA
what does acylation of lycine do?
act as flag to recruit chromatin remodellers - open up chromatin + transcription activators
where does methylation of DNA occur and what does it signify?
on cytosine bases - inactivates chromatin
what are epigenetic changes?
changes in chromatin structure that effect gene expression in chromatin but unalter the nucleotide sequence
what is rna splicing?
removal of introns +ligation of exons
what controls sex determination in drosophila?
RNA splicing - binding of proteins to exon-intron boundaries
what is 5’ cap strcutre?
signal requires for translation initiated of polyadenylated mRNAs (poly A tail)
what does free iron conc regulate?
regulates translation of mRNA coding for the iron storage protein (ferritin)
what happens at high and low free iron conentrations
high - aconitase dissociateds from ferratin mRNA so tranlation of ferritin occurs
low- aconitase binds to ferritin mRNA so translation is inhibited
