Trans-acting proteins that influence transcription are commonly referred to as
transcription factors
broadly used term for proteins that influence ability of RNA polymerase to transcribe a given gene by helping it bind to core promoter
trans-acting elements = DNA sequences containing a gene
cis-acting elements = do NOT code for prot
_______________ is used to describe a situation in which a gene's expression pattern is dependent upon the parent from whom it was inherited.
Genomic imprinting
Modifies cytosines in CG dinucleotides, often resulting in transcriptional silencing
Post-translationally modifies proteins by phosphorylating specific amino acids
Functions in association with other proteins to control gene expression by regulating chrom
DNA methyltransferase (transfers CH3 to C-G)
Protein kinase A (kinase=Phos)
SWI-SNF-family (remodels nucleosomes using ATP = ATP-dependent chromatin remodeling)
Histone deacetylase
DNA translocase (catalytic ATPase subunit that moves the protein complexes
Which of the following is not true of enhancer DNA sequences?
They contain the TATA box regulatory element
enhancer DNA = sequence that an activator (transcription factor/protein) binds to
TATA box is found in the core promoter DNA
enhancer DNA CANNOT be promoter DNA = cannot contain TATA box
Which of the following is a region in DNA that binds to a steroid receptor?
GRE
Glucocorticoid Response Element (DNA seq)
contains two consensus sequences found next to many genes and acts as enhancer
glucocorticoid = steroid
Hypercondensation of heterochromatin results in
transcriptional silencing
any condensing of DNA tends to silence it
Methylated CpG islands
Decrease transcription
anything methylated is not available for RNA
Histone H10
histone variant of H1
represses genes/compacts chromatin
descreases transcription
Acetylated histones
increase transcription
if histones are acetylated, not as tightly bound to DNA, DNA is more available for transcription
Phosphorylated CREB
Increase transcription
CREB protein = cAMP response element binding protein
Protein Kinase A phosphorylates it =
activation --> promotes CBP protein dimer to bind to it, which activates transcription
MacroH2A
Decreases transcription
histone variant
core histone; chromatin compaction
The ChIP technique can be used to identify putative DNA binding sites for various transcription factors since it
identifies DNA sequences bound to specific proteins
Chromatin immunoprecipitation (ChiP) tech =
1) cells treated with formaldehyde to covalently link proteins to DNA
2) cells broken open, chromatin exposed to high conc. of MNase that digests DNA
3) MNase
Which of the following would be suggested by a DNAse hypersensitive site?
The chromatin is in an open state and available for transcription
hypersensitive sites = sites where chromatin is sensitive to cleavage by DNAse I enzyme
this means the chromatin must be de-condensed
Which of the following would also work as an enhancer for the following bi-directional enhancer? 5' GTTC 3' 3' CAAG 5'
5' GAAC 3' 3' CTTG 5'
because it is flipped around, exact mirror of the original sequence = same enhancer
The association of DNA with histones to form chromatin affects transcription by
decreasing basal transcription rates
Zinc-finger peptide motifs are responsible for what aspect of protein function?
DNA binding
zinc finger = one alpha helix + 2 beta sheets + zinc ion
recognizes DNA sequences within the major groove of the double helix