Epigenetics

Question 1

Epigenetics

Answer 1

Study of heritable changes that do not change DNA sequence

Question 2

Epigenetic inheritance

Answer 2

Replication of methylated site->hemimethylated DNA so only parental strand methylated->constitutive DNA methyltransferases restore methylation of hemimethylated DNA

Question 3

Perpetuation of epigenetic effects through:

Answer 3

Protein structure assembled on DNA, covalent mod of DNA, protein aggregates that control conformation of new subunits

Question 4

Prion formation

Answer 4

Spontaneous generation of PrPc (normal glycoprotein), conversion of it to PrPSC (conformationally altered isoform), accumulation of PrPSC (toxicity)

Question 5

Prion inheritance and phenotypes come about through _________

Answer 5

Protein folding

Question 6

Heterchromatin extension ________ genes

Answer 6

Inactivates

Question 7

Epigenetic drift

Answer 7

Decrease in genome methylation within replications

Question 8

DNA methylation occurs at ________

Answer 8

CpG islands along DNA, on cytosines

Question 9

Methylation associated with ________ in eukaryotes

Answer 9

Transcription control, methylation=gene inactivation

Question 10

Telomeric silencing in yeast

Answer 10

Translocation of genes to telomeric region -> inactivation

Question 11

Histone methylation associated with heterochromatin formation

Answer 11

Genes in heterochromatin regions inactivated

Question 12

HP1

Answer 12

Key protein for mammalian heterochromatin, acts by binding to methylated histone H3

Question 13

SIR genes

Answer 13

Silent information regulators, drive heterochromatin formation in telomeres and silencing MAT locus in yeast

Question 14

Polycomb (Pc-G) and Trithorax (TrXG) group proteins

Answer 14

PcG maintain chromatin repression genes in a repressed state, TrXH antagonizes them. TrXH makes chromatin continuously accessible to TF

Question 15

DNA satellites

Answer 15

Very large arrays of tandemly non-coding, repeating DNA

Question 16

Methylation functional targets

Answer 16

1) Gene promoters (demethylation at promoters) 2) DNA satellites (centromere instability)

Question 17

DNA hypermethylation early event of ________

Answer 17

Tumorigenesis

Question 18

Tumor suppressor genes silenced in breast cancer

Answer 18

PTEN, APC, SFN

Question 19

Dosage compensation

Answer 19

Organisms equalizing expression of X-linked genes between members of different sexes

Question 20

Constitutive heterochromatin

Answer 20

Contain specific sequences without coding function

Question 21

Facultative heterochromatin

Answer 21

DNA regions inactive in one cell lineage but expressed in other cell lineages

Question 22

Single X hypothesis

Answer 22

Inactivation of one X chromosome in female mammals

Question 23

Chromosome condensation caused by ______

Answer 23

Condensins

Question 24

SMC (structural maintenance of chromosome) protein are ATPases (2):

Answer 24

Condensins: condensation into compact chromosomes during mitosis, cohesins: connect sister chromatids

Question 25

Genetic imprinting

Answer 25

Selective expression of gene according to the parental origin of the allele

Question 26

Imprinting does not follow classic ________

Answer 26

Genetics laws

Question 27

Imprinting is set in each sex during _________

Answer 27

Gametogenesis