1-41 Epigenetics

Question 1

imprinting

results in?

typically controlled by?

Answer 1

differential modification of maternal/paternal genetic contributions to the zygote.

results in differental expression of parental alleles

methylation - a downregulatory modification

Question 2

do you pass down imprinting patterns?

Answer 2

generally no. these patterns are reset in the germline at meiosis

Question 3

prader-willi syndryome

Answer 3

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

Question 4

angelman syndrome

Answer 4

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

Question 5

imprinting follows what kind of pattern?

Answer 5

tend to follow certain patterns depending on if an individual is male or female

Question 6

imprinting failure

Answer 6

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

Question 7

disomy

Answer 7

a state of having a pair of given chromosomes. The normal state for chromosomes to be in 2N cells.

Question 8

isodisomy

type of..

Answer 8

having inherited 2 copies of same chromosome homologue from one parents

type of uniparental disomy (UPD)

Question 9

heterodisomy

Answer 9

having 2 unique homogloes in a pair from the same parent

a type of UPD

Question 10

two types of UPD

Answer 10

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

Question 11

PWS individuals tend to…

Answer 11

gain weight rapidly, have developmental delay, bad temper

Question 12

AS individuals tend to be..

Answer 12

mentally retarded, hyperactive, seizes, happy/friendly demeanor

Question 13

what are epigenetics

categories?

Answer 13

study of heritble changes in gene function not caused by changes in DNA sequence

DNA methylation, histone modification, and chromatin remodeling

Question 14

hypomethylation

in an oncogene?

Answer 14

can result in a gene being over expressed, as methylation is ussually a down regulator.

if an oncogene is hypomethylated, cancer can ensue

Question 15

hypermethylation

in tumor supressor gene?

Answer 15

can result in gene being underexpressed

in tumor suppressor gene, gene is under expressed, can lead to cancer

Question 16

transcription factors are also part of _____

Answer 16

epigenetics

Question 17

Rett syndrome

Answer 17

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

Question 18

down regulation of certain miRNAs

due to?

can cause?

Answer 18

due to hypermethylation at their promotor regions

has been reported in a number of tumors

Question 19

offspring of women living in famine during pregnancy?

Answer 19

schizophrenia

Question 20

what determines differentiation?

Answer 20

Genes in all cells are the same, repertoire of which genes expressed or not expressed determines differentiation

Question 21

one genome for..

Answer 21

many different epigenomes

Question 22

what is an epigenome?

Answer 22

the globel epigenetic patterns that distinguish or are variable between cell types.

Question 23

DNA is typically modified by the..

Answer 23

methylation of C-G’s in promotors or body of DNA

when promotor gets methylated, it gets turned off

Question 24

describe chromatin

Answer 24

dynamic polymer. able to open up when a gene needs to get expressed, close down when it is not

Question 25

half of the gene sequence are

Answer 25

repeats. all being expressed would overwhelm the cell. the cell has mechanisms to turn off repeats so not constantly creating mRNAS - heterochromatin

Question 26

HPTMs

Answer 26

histone post-translational modifications - acetylation, phosporylation, methylation

Question 27

histone modification is important in (4)

Answer 27

transcriptional regulation, DNA replication, alternative splicing, chromsome condensation

Question 28

ncRNA can do what?

2 examples?

Answer 28

non-coding RNA - can guide specialized regions of the genome into more compacted chromatin states

• imprinting
• x inactivation

Question 29

microRNA’s - purpose?

product?

Answer 29

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

Question 30

the peptide bond (w) between the c=o of one aa and the N of another aa has what type of character?

Answer 30

partial double bond character due to delocalization of electrons. It therefor cannot turn.

Question 31

the phi and psi bonds can rotate

Answer 31

+180 to -180

Question 32

ramachandron plot analysis

Answer 32

dark colors - bond angles easily allowed
lighter color - allowed
lightest color - difficult
no color - impossible