Eukaryotic Gene Regulation II

Question 1

DNA methylation

Answer 1

ONLY silences gene transcription

Question 2

histone methylation

Answer 2

can activate OR silence expression

Question 3

H3K4me

Answer 3

activation of histone via methylation

Question 4

H3K9me

Answer 4

silencing of histone via methylation

Question 5

DNA methylation occurs on _

Answer 5

cytosines (C5) via DNA methyl-transferase

Question 6

cytosine methylation occurs most commonly in _

Answer 6

context of CpG islands with the cytosines of both strands being methylated

Question 7

MeCP2

Answer 7

recognizes methylated CpGs and recruits HDACs

Question 8

methylation in cancerous cells

Answer 8

tumor suppressor genes are silenced via methylation

Question 9

de novo methyltransferases

Answer 9

methylate completely unmethylated CpG –> expressed mainly in early embryo development and set up pattern of methylation

Question 10

maintenance methyltransferases

Answer 10

add methylation to DNA when one strand is already methylated –> work throughout life to maintain pattern set by de novo methyltransferases

Question 11

Rett syndrome symptoms

Answer 11

mental retardation, normal development until 1 years old, loss of speech and motor skills, seizures, microcephaly, ataxia, autism

Question 12

Rett syndrome mutation

Answer 12

mutation in MeCP2 prevents binding to methylated DNA and no recruitment of HDACs –> causes locus to be turned on

Question 13

MeCP2 is located _

Answer 13

on Xq28 (X chromosome)

Question 14

What would happen if there was a mutation in MeCP2 in a male?

Answer 14

the male embryo would die because they only have one X chromosome –> the resulting phenotype would be too severe

Question 15

MeCP2 duplication syndrome

Answer 15

extra copy causes silencing in other genes resulting in delayed motor skills and intellectual disabilities

Question 16

embryo beta-globin locus

Answer 16

epsilon

Question 17

fetus beta-globin locus

Answer 17

gamma-G and gamma-A

Question 18

adult beta-globin locus

Answer 18

beta and delta

Question 19

beta-thalassemia

Answer 19

beta-LCR deleted preventing transcription of the beta-globin locus

Question 20

functions the locus control region

Answer 20

establish an open, active domain of chromatin, enhance transcription of genes within the domain, insulate negative effects of adjacent sequences

Question 21

ligands that bind to nuclear receptors

Answer 21

cholesterol derivatives: testosterone, vitamin D3, retinoic acid, thyroxine, estradiol, cortisol

Question 22

nuclear receptors

Answer 22

have ability to directly bind to DNA and regulate transcription

Question 23

nuclear receptor mechanism

Answer 23

NR bound by HSP in absence of ligand (in cytoplasm) –> ligand binds –> HSP falls off and nuclear localization signal exposed –> receptors dimerize and go to nucleus –> find special DNA sequence –> bind –> transcription

Question 24

androgen receptor (AR) ligands

Answer 24

5-DHT, testosterone, and 5-reductase

Question 25

AR functions

Answer 25

1. male sexual differentiation
2. male behavior
3. sperm production at puberty
4. prostate development
5. sex drive

Question 26

AR gene regulation

Answer 26

protein synthesis, ligand binding, covalent modification, addition of second subunit, unmasking, and stimulation of nuclear entry

Question 27

androgenetic alopecia

Answer 27

male-pattern baldness due to increased AR activities in hair follicles

Question 28

spinal bulbar muscular atrophy (Kennedy’s disease)

Answer 28

neurodegenerative disease resulting from expanded CAG repeats in N-terminal domain of AR

Question 29

AR is located on _

Answer 29

X chromosome

Question 30

late-stage prostate cancer

Answer 30

AR mutations and amplifications

Question 31

androgen insensitivity syndrome (AIS)

Answer 31

loss of function AR mutation –> genetically male but has physical traits of woman