1-41 Epigenetics Flashcards
imprinting
results in?
typically controlled by?
differential modification of maternal/paternal genetic contributions to the zygote.
results in differental expression of parental alleles
methylation - a downregulatory modification
do you pass down imprinting patterns?
generally no. these patterns are reset in the germline at meiosis
prader-willi syndryome
imprinting issue
paternal chromosome 15 has female imprinting pattern
OR(female imprinting or 2 female copies)
individual is isodisomic for chromosome 15 from mother
or portion of fathers chromsone deleted, only expressing mothers
overweight, always incredibly hungry
angelman syndrome
an individuals maternal chromosome 15 has a male impriting pattern
man - male pattern
OR (male imprinting or two male copies)
individual is isodisomic for chromosome 15 from father
or deletion on maternal chromosome, leading only for paternal chromosome to be expresed
imprinting follows what kind of pattern?
tend to follow certain patterns depending on if an individual is male or female
imprinting failure
when germline cells in an individual fail to be imprinted properly for their gender
example) a man’s maternal chromosomes remain imprinted with female pattern after meiosis.
associated with - PWS and AS
disomy
a state of having a pair of given chromosomes. The normal state for chromosomes to be in 2N cells.
isodisomy
type of..
having inherited 2 copies of same chromosome homologue from one parents
type of uniparental disomy (UPD)
heterodisomy
having 2 unique homogloes in a pair from the same parent
a type of UPD
two types of UPD
having inherited 2 copies of the SAME chromosome homologue from one parent
or
a state of having two UNIQUE homologues in a chromosomal pair from the same parent
PWS individuals tend to…
gain weight rapidly, have developmental delay, bad temper
AS individuals tend to be..
mentally retarded, hyperactive, seizes, happy/friendly demeanor
what are epigenetics
categories?
study of heritble changes in gene function not caused by changes in DNA sequence
DNA methylation, histone modification, and chromatin remodeling
hypomethylation
in an oncogene?
can result in a gene being over expressed, as methylation is ussually a down regulator.
if an oncogene is hypomethylated, cancer can ensue
hypermethylation
in tumor supressor gene?
can result in gene being underexpressed
in tumor suppressor gene, gene is under expressed, can lead to cancer
transcription factors are also part of _____
epigenetics
Rett syndrome
neurodevelopmental disorder caused by a failure of MECP2 trancription factor to function. Lack of MECP2 that normally recognizes methylated DNA and ussually helps repress gene expression
down regulation of certain miRNAs
due to?
can cause?
due to hypermethylation at their promotor regions
has been reported in a number of tumors
offspring of women living in famine during pregnancy?
schizophrenia
what determines differentiation?
Genes in all cells are the same, repertoire of which genes expressed or not expressed determines differentiation
one genome for..
many different epigenomes
what is an epigenome?
the globel epigenetic patterns that distinguish or are variable between cell types.
DNA is typically modified by the..
methylation of C-G’s in promotors or body of DNA
when promotor gets methylated, it gets turned off
describe chromatin
dynamic polymer. able to open up when a gene needs to get expressed, close down when it is not
half of the gene sequence are
repeats. all being expressed would overwhelm the cell. the cell has mechanisms to turn off repeats so not constantly creating mRNAS - heterochromatin
HPTMs
histone post-translational modifications - acetylation, phosporylation, methylation
histone modification is important in (4)
transcriptional regulation, DNA replication, alternative splicing, chromsome condensation
ncRNA can do what?
2 examples?
non-coding RNA - can guide specialized regions of the genome into more compacted chromatin states
- imprinting
- x inactivation
microRNA’s - purpose?
product?
short non coding RNA’s, bind to 3’UTR to regulate
product is not a protein, it is RNA that seeks out genes and turns over a gamut of targets.
by expressing miRNA, we can turn off or on a repertoire of genes
the peptide bond (w) between the c=o of one aa and the N of another aa has what type of character?
partial double bond character due to delocalization of electrons. It therefor cannot turn.
the phi and psi bonds can rotate
+180 to -180
ramachandron plot analysis
dark colors - bond angles easily allowed
lighter color - allowed
lightest color - difficult
no color - impossible
