Lecture 12 Flashcards
(26 cards)
In _______ state:
Transcription factors and RNA polymerase can access the regulatory regions and
transcribe the gene
euchromatin
In _________ state:
Transcription factors and RNA polymerase are unable to access the regulatory
regions and transcribe the gene
heterochromatin
_________ – causing phenotypic changes by modifying how a gene is expressed,
rather than modifying the DNA sequence itself
Epigenetics
epigentic control alters __________
chromatin accessibility
what are the two ways epigentic modification can modulate access to genes?
modifications to histones
modifications to DNA
histone modification (epigenetics): ____________
Control gene expression by modifying histone tails
_________ add acetyl
groups to histone tails
Histone acetyltransferases
how does Histone acetyltransferases change the chromatin state? to which kind does it change to?
destabilizes the tight
packaging of nucleosomes, leading to a
more euchromatic chromatin state
Histone methylation involves adding methyl groups to histone tails by __________
histone methyltransferases
where does DNA methylation occur?
on cytosine bases
why does the covalent addition of methyl groups
generally turn off transcription?
blocks proteins from accessing the DNA sequence they need
true/false: Epigenetic modifications are heritable
true! The epigenetic modifications on the parent DNA strand can be copied to the daughter DNA strand
as it is synthesized
true/false: Environmental factors can influence epigenetic modifications -diet, stress, and exposure to toxins
true
which organ is most sensitive to epigenetic changes?
the brain
how do we generate different cell types?
A transcription regulator switches on its own gene
and other genes unique to the cell type
(Combinations of just a few transcription
regulators can give rise to numerous cell
types during development)
Regulatory ___ control the expression of
thousands of genes
RNAs
________ direct the destruction of target mRNAs
MicroRNAs
The mature miRNA (~22 nucleotides) is packaged with specialized proteins to form
an ________
RNA-induced silencing complex (RISC)
Once base pairing with a complementary mRNA sequence is established, a ___
in the RISC complex degrades the mRNA
nuclease
what kind of match do you need to rapidly degrade an mRNA with the nuclease in the RISC?
an extensive match
what kind of match do you need to eventually (slowly) degrade an mRNA with nucleases in the cytosol?
a less extensive match, partial match
_______: Protect cells from infections
small interfering RNAs, siRNA
Long double-stranded RNA is rarely produced by normal
genes; instead, it is typically intermediates in the life cycles
of _______
viruses
siRNAs are used in cells to…
Infected cell effectively turns the foreign RNA against itself
