Genetics: Gene Expression

Question 1

Histone Structure

Answer 1

Octamer of two copies of each of 4 types of histones

Question 2

Genomic Imprinting

Answer 2

Allele from either father or mother silenced so that only one is expressed

Question 3

Mech of Genomic Imprinting

Answer 3

DNA methylases methylate the cytosine on CG islands

Question 4

Differences b/w Type I and II Nuclear Rs (3)

Answer 4

I: binds R in cyt, II: binds R in nuc
I: releases repressor prots, II: releases corepressor prots
I: forms homodimers, II: most often forms heterodimers, requiring two different signalling molecules

Question 5

Examples of Type I (4) and Type II (3) Nuclear R Signalling Molecules

Answer 5

Type I: E, P, androgen, glucocorticoid

Type II: Vit A, Vit D, thyroid hormones

Question 6

Coregulators (3)

Answer 6

Majority histone-modifying enzymes causing chromatin remodeling (coactivators releasing histones from DNA and corepressors causing condensation)

Question 7

Histone Code Hypothesis

Answer 7

Modifications of histone residues (acetylation, methylation, phosphorylation, ubiquitylation) causes chromatin remodeling leading to either DNA condensation (inactivation) or relaxation (activation)

Question 8

Process of GPCR (5)

Answer 8

Ligand binds GPCR which acts as GEF on Galpha which activates adenylyl cyclase which forms cAMP which activates PKA to activate regulators of transcription

Question 9

Attenuation of GPCR Response

Answer 9

PKA also activates phosphodiesterase (PDE) which hydrolyzes cAMP

Question 10

Two Major Points from Wnt Canonical Pathway

Answer 10

Is classified as GPCR

Activates transcription via Beta-catenin

Question 11

JAK-STAT Pathway (4)

Answer 11

Cytokine binds cytokine R, causing neighboring Jak to phosphorylate Tyrs on R, read by SH2 domain of Stat which dimerizes to activate transcription

Question 12

MAPK Pathway (4)

Answer 12

RTK activated by growth factors/mitogens, recruits GEFs to activate Ras which activates MAP kinase pathway which activates transcription factors

Question 13

Crucial 2 Points of Growth Response Pathways

Answer 13

Kinases and G prots drive growth and their GAPs inhibit it

Question 14

S6K1-HM

Answer 14

Crucial point of growth regulation, when AID region dissociates can stimulate transcription

Question 15

Strongest Tumor Repressor

Answer 15

Phosphatase

Question 16

Insulin R Pathway Notable Feature

Answer 16

Can activate both MAPK pathway and PI3K-mTOR Pathway

Question 17

Insulin R non-MAPK Pathway (7)

Answer 17

Insulin binds, causing autophosphorylation, activating PI3K which activates PDK1 which activates PKB which inhibits Rheb GAP so Rheb G prot can activate mTOR protein kinase to stimulate transcription

Question 18

Starvation Response

Answer 18

LKB1/AMPK respond to low nutrient/energy by activating Rheb-GAP which downregulates mTOR

Question 19

Oncogene

Answer 19

Gene that becomes cancer causing agent due to hyperactivation via mutation or overexpression. Usually in cell signaling pathways that drive cell growth

Question 20

Stress Response

Answer 20

Stress activates kinase to phosphorylate eIF2/eEF2 which blocks translation

Question 21

RNAi

Answer 21

miRNA binds w/ Argonaut to form RISC which can directly cleave or block specific RNA sequences, so can be used to block specific genes

Question 22

Opioid R Agonists (action, effect, 3 examples)

Answer 22

Stimulates GPCRs for pain relief/euphoria - morphine, codeine, oxycodone

Question 23

Caffeine Mech

Answer 23

GPCR Purinergic R Antagonist, but that R antagonizes adrenergic R so it acts as a stimulant

Question 24

Adrenergic R Agonists (action, effect, 3 examples)

Answer 24

GPCR agonists that mimic adrenaline, so stimulants (ephedrine, pseudoephedrine [sudafed], amphetamines)

Question 25

Difference b/w Histamine H1 and H2 R Antagonists

Answer 25

H1s for allergies and H2 for stomach acid

Question 26

Dopamine R Agonists (2 examples)

Answer 26

Cocaine and Thorazine (for schizophrenia)

Question 27

3 Kinds of Steroid Medicines

Answer 27

Glucocorticoids (anti-inflammatory/immunosuppressants), anabolic steroids (bone/muscle growth), female needs like E&P

Question 28

Gleevec

Answer 28

Turning point in cancer treatment, kinase inhibitor for leukemia

Question 29

4 Kinds of Kinase Inhibitors for Cancer Treatment

Answer 29

BCR-Abl - leukemia
EGFR - lung/pancreatic
mTOR - immunosuppressant for transplants
JAK - antiinflammatory

Question 30

Rapamune

Answer 30

mTOR inhibitor which acts as immunosuppressant so used for transplants