Chapter Twenty: Epigenetics Flashcards
three techniques to monitor regulation of gene expression
- northern
- microarray
- RT-PCR
techniques to monitor gene expression depend on ___
hybridization
heritable alterations in gene expression that do not involve a mutation or change in base pairing
epigenetics
the DNA sequence in genes is not the only carrier of ___
genetic information
write the definition of epigenetics
heritable self-perpetuating changes in gene expression not caused by base pair sequence changes
epigenetics usually involves modified ___, ___, or ___
cytosine residues, histone tails, or small RNAs
epigenetic factors determine whether a gene is ___ or ___
on or off (expressed or not)
phenomenon in which expression of an allele depends on the parent that transmits it
genomic imprinting
about ___ imprinted genes have been identified
100
paternal allele is not transcribed
paternally imprinted
maternal allele is not transcribed
maternally imprinted
imprinted means ___
silenced
a methyl group is added to the cytosine base in a 5’ CpG 3’ dinucleotide by DNA methyltransferase
DNA methylation
regions with a high concentration of CpG dinucleotides
CpG islands
CpG islands are usually ___ and located near a ___
unmethylated
promoter
an ___ binds to unmethylated CpG islands, the chromatin is ___ and transcription is ___
activator
open
activated
DNA methylation at CpG islands ___ gene expression
silences
repressors called ___ bind to methylated CpG islands and close the chromatin structure
methyl-CpG-binding proteins (meCPs)
cytosine methylation pattern is ___ during DNA replication, so DNA methylation is ___ throughout cell division
copied
maintained
special ___ at the replication fork methylates the newly synthesized DNA strand
DNMT
sex-specific DNA methylation mediates ___
imprinting
imprinting occurs through these two mechanisms
- insulator mechanism
- ncRNA mechanism
epigenetic imprints remain throughout the ___ of an animal
life span
in germ cells, epigenetic imprints ___ each generation
reset
during meiosis, imprints are ___ and new ones are set based on the ___ of the organism
erased
sex
human ___ show imprinting
pedigrees
___ syndrome occurs when a deletion in chromosome 15 comes from the father, ___ syndrome occurs when it is inherited from the mother
prader-wili
angelmans
imprinting only occurs in ___
placental mammals
most imprinted genes control ___
prenatal growth
imprinting is ___ (100 genes identified so far)
rare
all cells in multicellular organisms have the same ___
genes
cell types are different because of ___ differences
gene expression
determines gene expression and potential fates of a cell, often a transcription factor
master regulator
cells “remember” their fate from cell generation to generation partly because histone modifications that repress transcription at master regulatory genes are ___
copied at the replication fork
drosophila Cox (homebox) genes encode transcription factors that set up animals ___
segmented body plan
highly compacted chromatin found in all cells
constitutive heterochromatin
constitutive heterochromatin is found at ___, which are enriched in ___; important to prevent ___
centromeres
transposable elements
TE mobilization
constitutive heterochromatin is also found at ___
telomeres
___ transcribed from centromeres initiates heterochromatin formation
ncRNA
ncRNA is converted to ___ which binds to ___
siRNA
argonaute (ago)
ago recruits ___ that results in heterochromatin formation
histone methyltransferases
plant heterochromatin is ___ after cell division
reformed
which base gets methylated in epigenetic control
cytosine
mammalian cells ___ which X chromosome was inactivated
remember
when an environmentally induced trait (not caused by a base pair mutation) appears in an individual’s descendants whose DNA was not directly exposed to the environmental trigger
transgenerational epigenetic inheritance
methylation marks are released during meiosis in ___ but not ___
animals
plants
piRNAs transmit memories of ___
TE invasion
organisms try to ___ TE mobilization to prevent mutations or chromosomal rearrangements
limit
why can TEs move with a minimal effect on phenotype in humans?
only 1% of the human genome codes for proteins that affect phenotype
environmentally induced trait that is displayed only in the child, or child and grandchild of an originally exposed female, or child of an exposed male
intergenerational epigenetic inheritance
