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29 Cards in this Set

  • Front
  • Back
does chromatin condensation or decondensation lead to activation of gene transcription? Repression of gene transcription?
decondensation; condensation
what defines euchromatin? Heterochromatin?
less condensed chromatin; more condensed chromatin
what is constitutive heterochromatin? Give 2 examples.
regions of chromatin that are always highly condensed; centromeres or telomeres
what is facultative heterochromatin?
euchromatic regions that can assume a more condensed chromatin organization
what is CpG?
a cytosine nucleotide following in sequence by a G nucleotide (note: they are NOT base paired but rather connected by a phosphodiester bond)
what is the role of de novo methyltransferases?
covalently attach a methyl group to cytosine residues of CpG dinucleotides devoid of methyl moieties to generate hemi-methylated CpG's
what is the role of maintenance methyltranferases?
methylate hemi-methylated CpG's to generate fully methylated DNA (both strands)
does DNA methylation generally correspond to transcriptional repression or activation?
is the pattern of histone modifications inherited during mitotic cell division?
yes, faithfully
to what does the 'histone code' refer?
overall pattern of all histone modifications
for what does HAT stand? What do HAT's do?
histone acetyltransferase; covalently attach an acetyl group to the amino group of the side chain of lysine residues in the tails of histones 2A, 2B, 3, and 4
for what does HDAC stand? What do they do?
histone deacetylase; remove the acetyl hroups of acetylated lysine residues
in general does histone acetylation correspond to active gene transcription or inactive gene transcription? Histone deacetylation?
active; inactive
for what does HMT stand? What do HMT's do?
histone methyltransferase; covalently attach a methyl group to the amino group of the side chain of lysine and arginine residues in the tails of histones 3 and 4
does methylation at arginine residues correspons to active gene transcription or repression? Lysine residues?
transcription; either
what is the role of chromatin remodeling complexes?
to remodel chromatin by breaking and re-forming histone-DNA contacts thereby causing mobilization of nucleosome on chromosome
which part of the chromatin remodeling subunit is the catalyst?
ATPase subunit
do nucleosomes promote or inhibit gene activation?
does the activity of chromatin remodeling complexes normally result in the repression or activation of gene transcription?
it can result in either depending on the gene and promoter
can histone modifications, chromatin remodeling complexes, and DNA methylation interact?
are Barr bodies normally composed of euchromatin or heterochromatin?
what term is used to describe the expression of X-linked genes in women?
what is the name for the region in which the Xist gene is found on X chromosomes?
X chromosomes inactivation center (XIC)
what is the product of the Xist gene?
RNA molecule which coats the future inactive X chromosome which is the first step in X inactivation
following X inactivation, which other processes help to inactivate the X chromosomes in Barr bodies?
histone modification and DNA methylation
what is the name for the process in mamallian gametogenesis where about 70 genes become silenced in germ cells in a sex-specific manner?
genomic imprinting
what is the name for genes on female gametes that are silenced during genomic imprinting? Male gametes?
maternally imprinted; paternally imprinted
what is the consequence of genetic imprinting?
after fertilization, imprinted genes are expressed as if there were only one copy of the gene present in the zygote genome even though two copies are present
which techniques are responsible for turning genes required transiently during development or in termially differentiated cells on or off? What is often the first step in the establishment of these genetic marks?
histone modifications and DNA methylation; recruitment of HDAC's or HAT's through transcriptional repressors or activators