Genetics Quiz 2: Epigenetics and DNA methylation

there are over 20-_____ genes in human genome and over _____ distinct cell types. thus

20-25,000 genes over 200 distinct cell types THUS each cell must select some genes to turn on or silence.

A beta cleavage followed by gamma cleavage generates

A-beta peptide fragments

what is the viable yellow agouti allele

A^vy

what is mouse color from

Agouti gene

DNA methylation at promoters of BACE1 and PSEN1 is low in

Alzheimer's neurons basically in normal cells, there's more methylation at the promoters in the CpG island in BACE1 and PSEN1 and so the gene gets silenced.

Alzheimers disease is characterized by inappropriate cleavage of

Amyloid precursor protein (APP) cleaved wrong leading to beta-amyloid plaques

Beta cleavage is facilitated by

BACE1

many CpG sites next to each other can be called a

CpG island

in DNA methylation, cytosine can be methylated at

CpG sites

what methylates CpG sites

DMNT

expression of A^vy can be modulated by

DNA methylation

the phenotype of mice directly reflects the amount of

DNA methylation at the pseudo-exon

what is DNA and histones like in euchromatin

DNA unmethylated histones acetylated

main thing used in treatments for these disorders

HDAC inhibitors

Gamma cleavage is facilitated by

PSEN1

even tho the Avy gene comes in to make the a allele come out more and cover up the A agouti, what can turn it the other way

The Avy comes with a CpG island!!! This means it can be methylated and deactivated this leads to a "pseudoagouti" which is almost agouti but not quite because the yellow got silenced again

how does agouti transcription work in hair follicles

begins at an alternative TSS in Exon 2 produces the appropriate amount of gene product basically exon 2 controls the gene expression

Gene transcription can be regulated thru interaction of

cis-acting elements (promoters, enhancer and silencer sequences) and DNA binding proteins like transcription factors

epigenetic modifications can integrate developmental events and environmental cues as well as contribute to

disease progression

examples of abnormal epigenetic landscapes

diseases like cancer and neurodegenerative diseases

what does A^vy do

ectotopic (inappropriate) expression of the "a" gene. overexpresses the a allele, makes it yellow even if A is present.

how are methylation patterns inherited

epigenetic imprinting

what is it called when u modify histones, chromatin state, or DNA

epigenetic regulation because it shows heritable effects without changing DNA sequence itself

A allele causes

eumelanin (dark pigment) Agouti usually dominant

when is the level of methylation established

fetal development by the nutritional state of the mother

when the CpG island on the promoter is unmethylated then what

gene can be transcribed NO METHYL = CAN BE TRANSCRIBED

all cells have the same ____ but different _____

genome epigenomes

healthy mom =

healthy babies

highly methylated health and diet

healthy weight supplemented diet (folate, b12, etc.)

DNA methylation stimulates

heterochromatin

epigenetics

how diff cell types use the same genome

inheritance of traits not coded for in the DNA sequence can be referred to as

imprinting

where are CpG sites normally

in or near promoter regions and participate in gene silencing

what is A^vy from

insertion of a pseudo exon before the actual exon 2.

after DMNT starts methylating,

methyl binding proteins (MBD) recognize the modification and recruit HDACs to begin deacetylating nearby histones

besides cis acting elements what else can provide more regulation

modifying histones, chromatin state, and chemical alterations to DNA

unmethylated health and nutritition

obesity control diet aka ectotopic expression

a allele causes

phaeomelanin (yellow)

methylated Avy phenotype

pseudoagouti Avy is there but it got deactivated by the methylation

as development happens, cells become differentiated and programs of gene expression become more and more

restricted

methylation at CpG islands in or near promoters can

silence gene expression

When a promoter is methylated (with the CpG in it) what happens to the gene

silenced

what does the HDAC trigge r

stimulates heterochromatin around CpG islands

methylation at the pseudo-exon can

suppress phenotypes and improve health

what makes it hard for transcription factors to find their binding sites

the methyl groups protrude into the major groove of the helix making it hard for transcription factors to find their sites

Avy mothers frequently pass on this allele along with the same methylation state to

their pups Avy yellow (unmethylated) make Avy yellow (unmethylated babies)

what happens when these fragments come together

they make harmful amyloid plaques

what is special about CpG

this is where methylation can happen can silence genes

unmethylated phenotype Avy

yellow Avy doing its work without any interference. Masks the agouti