chapter 12 Flashcards
TATA box
binding site for TBP/TFIID, in promoter region
promoter proximal elements
GG box and CCAAT box,
present upstream of most genes, binding site of the broadly expressed transcription factors
cis acting DNA sequence elements
enhancers, proximal elements, and core promoter
trans-acting proteins
transcription factors
mutation on promoter proximal elements ____ transcription rate
decreases
enhancers/silencers
lead to differences in gene expression, binding sites are very cell and condition specific
Gal4 (what does it do)
regulates Gal, Gal2, Gal7, and Gal10 when they’re needed for glycolysis
Gal4 activity is regulated by…
Gal80 and Gal3
Gal4 binds to what and recruits what
binds to specific DNA sequence (UAS)
recruits transcriptional machinery
enhancesome
synergistic complex formed by multiple transcription factors responsible for interaction between enhancer and promoter region
epigenetic regulation mechanisms (2)
- modification of chromatin structure
- modification of DNA (methylation)
how is eukaryotic genomic DNA packed
packaged into chromatin, the DNA wraps around histone to form nucleosome
euchromatin
allows gene expression
heterochromatin
silenced (super tightly packed)
constitutive heterochromatin
always highly condensed (centromeres and telomeres), mostly repetitive sequences and few genes
euchromatic heterochromatin
can change to heterochromatin (falculative heterochromatin)
chromatin remodelling
can change nucleosome position to permit transcription
cis regulatory: elements inaccessible
exposed: elements accessible
modification of histone tails…
affects chromatin structure
modifications of amino acids…
affect histone-DNA interaction and nucleosome packaging, can attract activators or repressors
acytelation of histone tails
promotes OPEN chromatin structure and transcription
deacytelation of histone tails
promotes chromatin condensing and silencing
regulation of B interferon
transcription factors, histone modifications, and chromatin remodeling JOIN FORCES
architecture proteins
bend DNA to facilitate interactions between transcription factors and enhancesome
architecture protein steps
- enhancesome binds with GCN5 which adds acytl
- GCN5 recruits CBP (more acytl), swl-SNF (nudges nuc2) and RNA polymerase II
- TBP (TATA binding protiens) bind to TATA and starts transcription
methylation
maintains chromatin condensation
mehtylation steps
- usually on cytosine in a GC dinucleotide, they’re hypermethylated
- CpG islands: clusters of unmethylated CF
- when CpG island near the promoter is methylated, gene expression is inhibited
imprinting
allele inherited is inactive (always the same parent)
maternal imprinting
maternal allele is inactive
paternal imprinting
paternal allele is inactive
DNA binding domain
essential for transcription factors activity (for Gal4, it’s essential in activating the transcription pathway