Epigenetics Flashcards
The changes in gene expression or phenotype that are potentially heritable without altering the underlying DNA base sequence is called
Epigenetics
what coined the term epigenetics
Conrad Waddington
what molecular process lead to epigenetic changes
1.changes in chromatin structure altering gene expression
2. molecular mechanisms that alter chromatin structure.
what is the addition of methyl groups to nucleotide bases
DNA methylation
what is the most common methylation
methylation of cytosine to produce 5-methylcytosine
methylation occurs in single or both DNA strands
both DNA strands
what is a common epigenetic modification of chromatin
DNA methylation
what is responsible for the differences in the phenotypes of honeybee queens and workers
Epigenetics in DNA methylation
histone modification are on the tails or head that interact with DNA
tails
histone modification affect
chromatin structure and gene transcription.
the post-translational modification of histones are called
epigenetic marks / histone code
Post translational modifications inludes
addition of phosphates, methyl groups, acetyl groups, ubiquitin
Acetylation of histones destabilizes the chromatin which affects transcription in what way
increased transcription
deacylation affects transcription in what way
decreases transcription
what histones are associated with active transcription
H3 K4 Me3 AND H3 K36 Me3
what histones are associated with transcriptional repression
H3 K9 Me3 and H4 K20 Me3
effect of hypoacetylated lysine on transcription
repression
effect of acetylated lysine on transcription
activated
effect of methylated lysine on transcription
activation, elongation, repression
effect of methylated arginine on transcription
activation
effect of ubiquitinylated lysine on transcription
activation, repression
do single histone modifications individually determine the transcriptional activity of a gene. true/false
false, it is the combined presence of a multiple epigenetic marks
explain crosstalk
cross talk between epigenetics such that one histone mark may affect whether additional marks occur nearby and how they finction
why do crosstalks occur?
because epigenetic marks recruit enzymes and protein that modify other histone
Epigenetic effects by
RNA molecules
an interaction between two alleles that leads to a heritable change in expression of one of the alleles
Paramutation
explain paramutation in corn
a copy of the B’ allele converts the B-I allele to B’*, which has the same phenotype as B’
pigmentation of b1 corn locus
B-I B-I produces a pigmented plant
B’ B’ and B’ B* lightly pigmented
paramutation in Kit locus in mice
a cross between kit+Kit+ and kit+kit t produces some kit+kit+ with phenotypes of Kit+ kit+ and kit+kit t
life experiences, especially early in life having long-lasting effects on behavior is called
bahvioral epigenetics
Effects of epigenetics
behavioral epigenetics
changes induced by maternal behavior
early stress in humans
in cognition
environmental chemicals
licking and grooming of offsprings in rodents affects
DNA methylation
childhood abuse leads to
more methylation of glucocorticoid receptor gene
histone acetylation in mice improved
learning and memory in mice with a Alzheimer like disorder
what is the effect of maternal behavior in mice
alters the expression of stress-response genes which makes them less fearful as adult
what fungicide acts as an endocrine disruptot increasing DNA methylation in sperm
vinclozin (prevented sperm production in treated animals)
the offsprings of males on the low protein diet has
increased expression of genes involved in lipid and cholesterol metabolism and differences in DNA methylation
explain epigenetic effects in monozygotic twins
methylation and acetylation patterns were similar in early life but older twins are different in gene expression
how is X inactivation a type of epigenetics
x inactivation results in a stabel change in gene expression that is passed on to daughter cells
X-inactivation starts at
X inactivation center and spreads to the remainder of the X chromosome
what gene on the inactive X produces an long noncoding RNA that coats the inactive X chromosome and suppress transcription
Xist gene
what gene inhibits transcription of Xist on active chromosome
Tsix
what gene stimulates trasncription of Xist on inactive X chromosome
Jpx
what gene sustains Tsix exoression on active X, which inhibits Xist and maintains transcription
Xite
stem cells are undifferentiatec cells that can generate every cell type in an organism, this property is called
Pluripotency
gene expression profile during cell differentiation is
increasingly fixed
the transcription factors that induce pluripotency causes
extensive epigenetic reprogramming which alters patterns of DNA methylation and histone modifications
effect of reprogramming differentiated adult cells forms
induced pluripotent stem cells (iPCSs)
epigenetics in genomic imprinting
the expression of an allele depends on whether it is inherited from male or female parents
what is the overall pattern of chromatin modification possessed by each individual organism
Epigenome
what are used to detect DNA methylation
restriction endonucleases
bisulfate sequencing
waht is used to detect histone modifications
ChIP
what can be used to determine the locations of 5-methylcytosines
bisulfate sequencing
