Control of gene expression Flashcards
exam 1
cell types are determined by
differential gene expression resulting in different proteins
basic functions for cell sustenance
Housekeeping
example of a housekeeping gene
ribosomal proteins
formed as DNA wraps around a histone octamer
nuclesome
nucleosomes are not accessible to ______ when compared to free DNA
DNase I
trasncriptionally inactive
heterochromatin
transcriptionally active
euchromatin
accessible to limiting amounts of DNase I
euchromatin
not accessible to limiting amounts of DNAse I
heterochromatin
requires chromatin structure rearrangement so that RNA polymerase may bind
Gene activation
regulate chromatin organization over chromosomal domains
Locus control regions
LCR example
all globin genes
can alter chromatin structures
protein complexes
protein complexes that can alter chromatin structure example
SWI-SNF
Protein Complexes are thought to act globally to ____ mobility of ________ throughout the genome but some may target specific genes
Protein Complexes are thought to act globally to increase mobility of nucleosomes throughout the genome but some may target specific genes
leads to unfolding of chromatin leading to transcritptional activation
histone acetylation
histone acetylation happens in
lysine residues
Many transcriptional “activators” have histone ____________ activity
acetyltransferase (HAT)
Many transcriptional “repressors” are histone _________
deacetylases (HDAC)
diminished gene expression
presence of methyl groups in promoter regions
gene activity associated with
absence of methylation
key mediator of X-inactivation
CpG
____ _________ adds a methyl group to the _____carbons atom of some, but not all, cytosine residues in ____ ________
DNA methyltranserase adds a methyl group to the fifth carbon atom of some, but not all, cytosine residues in CpG dinucleotides
CpG dinucleotides sequences are _______ for mutations because ______ of 5-methyl cytosine forms _____ and _____ _____ will not register this as a mutation
CpG dinucleotides sequences are hotspots for mutations because deamination of 5- methyl cytosine forms thymine and repair machinery will not register this as a mutation