Chapter 21 - Epigenetics

Question 1

Study: if paternal grandfather had abundant food in childhood, his grandchildren were __% more likely to die from diabetes in __ compared to individuals whose grandfather experienced famine.

Answer 1

400%!!!!!!; adulthood

Question 2

Epigenetics is transmission of __ or a biological __ without changing the DNA sequence.

Answer 2

phenotype; process.

Question 3

Nearly all epigenetic phenotypes are the result of changes in __ structure that occur by 3 major processes: DNA __; __ modification, and RNA __.

Answer 3

chromosome;
methylation;
histone;
molecules.

Question 4

In eukaryotes, methylation is almost exclusively on __ of __ islands. In mammals, these __ islands are most often located near __. Methylation of these islands leads to __ of transcription.

Answer 4

cytosine; 
CpG.
CpG;
promoters.
repression

Question 5

Methylation of cytosine is accomplished with an enzyme called __.

Answer 5

methyltransferase

Question 6

Queen bees and workers are almost genetically identical, but __ changes are induced by __ __. This substance represses the expression of the enzyme __ that is encoded by Dnmt3, which, in turn, allows for transcription of genes otherwise __ in worker bees. __ __ (aka __) can also be used to repress Dnmt3.

Answer 6

epigenetic; royal jelly.
methyltransferase.
silenced/repressed.
RNA interference; RNAi

Question 7

Methylation represses transcription in a simple way: the methyl at the _ position of cytosine lies within the __ __ of the helix. This methyl group does several things: it inhibits bindings of some transcriptional __ via __ hinderance; it attracts other __ type proteins; it attracts the enzyme histone __; and it promotes the formation of __.

Answer 7

5th; major.
activators; steric; 
repressor;
deacetylase; 
heterochromatin

Question 8

Histone modifications as well as methylation of __ on __ islands affect activation of transcription and chromatin structure; these are known as __ __.

Answer 8

cytosine; CpG; Epigenetic marks.

Question 9

Epigenetic marks do not function in __; they ___ with other epigenetic marks and influence cell __ check points, DNA __ pathways, and proteins that __ chromatin structure.

Answer 9

isolation; interact; cycle; repair; alter

Question 10

One of the best known examples of RNA molecules that induce epigenetic effects is the __ RNA; this RNA molecule is responsible for X-chromosome inactivation. It binds to extensive portions of the X-chromosome and attracts __ __ __ __ (PRC2) which methylates a specific lysine residue on __.

Answer 10

Xist.
polycomb repressive complex 2;
H3

Question 11

__ violate Mendel’s law of segregation. Basically, in heterozygotes, there is an interaction between two different __ that leads to heritable changes in the expression of one of the __ in future generations - it can even affect the expression of the other __ when NOT present!!!

Answer 11

Paramutations.

alleles; alleles; allele

Question 12

Rats whose mothers spent more time grooming them were less fearful and coped with stress better. This is evidence of __ Epigenetics.

Answer 12

Behavioral

Question 13

When deacetylase inhibitor is injected into a rat, what does it do?

Answer 13

Acetylation of histones neutralizes their tails and causes chromatin to relax. Deacetylase would have the opposite effect. So inhibiting deacetylase will cause acetyl groups to be added to histone tails thereby neutralizing them and causing the chromatin to relax.

Question 14

What are the methylation and acetylation patterns of monozygotic twins in childhood v. adulthood?

Answer 14

Childhood patterns were the same, adulthood patterns were different.

Question 15

The sex of the parent transmitting the allele impacts the expression of the allele in the progeny (e.g. gene Wrx17 is expressed only when the mother transmits it) - this is known as __ __.

Answer 15

genomic imprinting.

Question 16

The collection of specific chromatin mods of an individual are known as their __.

There are also differences in the __ of cancer cells v. normal cells.

Answer 16

epigenome.

epigenome.