ch 10 Flashcards
Lyon hypothesis/ dosage compensation
ermmmm extra XS and shit
Barr body
randomly turns off an X chromosome
x chromo inactivation controlled by
-upregulation expression of XIST and Jpx (2 lincRNA)
-down regualating Six
-histone mods
how x chromo deactivation works
XIST coast histone/ proteins to make it tight
poly II is excluded
is there mono allelic expression of all x linked gene
no
psudoautosomal regions expressed and maybe outside of this one too (25%)
transposable elements
move about the genome
a lot in bacteria plants and animals
selfish DNA
prevents transposition
methylated cytosine
barbara mcclintock
mobile genetic elements in corn
retrotransposons and types
RNA intermediate
LTR (long terminal repeat) and Non LTR
DNA transposons
DNA intermediate
DNA transposons moves by
cut and paste, need diverted terminal repeats, transposase
leaves a little DNA behind
retrotransposon I moves by
copy and paste,
LTR at both ends
non LTR- has poly A sequence at 3’ end
non LTR retrotransposons include
LINEs
SINEs(short)- nonautonomous, 21% of human genome, active ALU
LINEs
long, autonomous, 21% of human genome, L1 element, seconds RNA binding protein, encodes endonuclease and reverse transcriptase
SINEs
(short)- nonautonomous, 21% of human genome, active ALU, does no make enzymes
silencing transposons
methylation, heterochromatin formation mediated by RNAi and RNA directed DNA methylation, PIWI interacting RNA
epigenetic
heritable chasing in gene expression that occur with out a change in the primary DNA sequence of an organism
epigenome
chemical modification of genome. DNA mod and post translation mods of histones
epigenetic change causes
aging, development, behavior, environment, infection, cancer
intergeneration epigenetic inheritance caused by
mom nutrition, behavior during/before pregnancy, fathers nutrition/ behavior
epigenetic markers
modifications of chromatin structure (DNA methylation), histone modifications
major DNA mod in plants and animals
methylation of cytosine
major type of DNA modification in bacteria
methylation of adenine
methylation
blocks proteins that attach to DNA, silences
CpG in mammals
70-80%
most common methylation location
in transposable elements or repetitive sequences
most common methylation location exceptions
CpG islands
CpG islands
in promoters of housekeeper genes, near 5’ end of gene, to protect from methylation
deamination
mutations of 5-methylcytosine
gene dosage
number of cops of a gene in genome
monoallelic expression
gene transcribed preferentially form a single allele in each cell
random monallelic expression examples
immune system and olfactory nurons
genomic imprinting
selection of active allele based on parent origin
how many imprinted genes are in mammals
200
imprinted gene defects are associated with
defects
imprinting control region
methylation/ not methylated single or a group of imprinted genes
epigenetic methods
- DNA Methylation
- Histone Modifications
- Non-coding RNAs
epigenetic purpose
- Gene Expression Control
- Monoallelic expression
- Gene Imprinting
- X-inactivation – Dosage compensation
- Stop transposable element movement
Barbara McClintock’s contributio
corn lady, discovered the shit
Silencing Transposons
methylation, Histone modifications, RNA interference (RNAi)
– Heterochromatic small interfering RNA (siRNA)‐
– PIWI-interacting RNA (piRNA)
