Week 2 Richter Lectures

Question 1

a group of genes, regulated together by transcription from a single promoter that produces polycistronic mRNA

Answer 1

operon

Question 2

repressor binds to operator= what to transcription

Answer 2

inhibits

Question 3

what is used to break down lactose

Answer 3

lac operon (found in prokaryotes)

Question 4

Trp bound to repressor causes what to transcription

Answer 4

inhibits (Trp operon-found in prokaryotes)

Question 5

acetylation of histones does what

Answer 5

turns on gene expression

Question 6

methylation of histones does what

Answer 6

turns off gene expression (silences it)

Question 7

what often happens to cancer (acetylation and methylation example)

Answer 7

oncogenes need to be methylated (to silence the gene)

Question 8

drug used in anti-cancer chemotherapy that can reverse gene silencing, reduce proliferation, and trigger apoptosis

Answer 8

Vorinostat (drug that inhibits HDAC)

Question 9

remove acetyl groups from chromatin, which often silences gene expression

Answer 9

histone deacetylases (HDACs)

Question 10

what happens when gene expression is activated that should instead be silenced

Answer 10

cancer

Question 11

if these get methylated, they won’t be able to stop cancer

Answer 11

tumor suppressors

Question 12

3 functions of transcription factors

Answer 12

1. DNA binding domain
2. dimerization domain
3. activation domain

Question 13

a DNA-binding domain that allows TFs to insert themselves into grooves of DNA; Cys or His residues bound to Zn2+

Answer 13

Zinc finger

Question 13

what receptors are basically transcription factors

Answer 13

nuclear receptors

Question 13

DNA binding domain that has + and - charge by ionic interaction

Answer 13

basic domain

Question 13

mutation of Vitamin D receptor leading to vitamin D deficiency

Answer 13

Rickets

Question 13

mutation in thyroid hormone receptor leads to low T3 and thyroxine

Answer 13

Hypothyroidism

Question 13

mutation of cortisol receptor leading to high levels of corticosteroids

Answer 13

Cushing’s Disease

Question 13

nuclear receptor used in birth control (combination of 2)

Answer 13

estrogen/progesterone

Question 14

mutation of retinoic acid receptor; can cause developmental defects in embryo and fetus

Answer 14

retinoic acid derivatives

Question 14

used for acne and is contradicted during pregnancy

Answer 14

retinoic acid

Question 15

2 dimerization domains

Answer 15

leucine zipper and HLH (helix-loop-helix) domain

Question 16

All transcription factors are what

Answer 16

dimers

Question 17

leucine residues are where on the helix (for leucine zipper)

Answer 17

on the same face

Question 18

transcription factor class that control fundamental architectural plan of developing embryo

Answer 18

helix-turn-helix (from Hemeobox (Hox) genes)

Question 19

key process in gene silencing and defense against viral infections

Answer 19

RNA interference (RNAi)

Question 20

main player in RNA interference (gene silencing)

Answer 20

miRNA

Question 21

activates and cleaves mRNA during miRNA synthesis and gene silencing

Answer 21

RISC (RNA induced silencing complex)

Question 22

regulated process during gene expression that results in a single gene coding for multiple proteins

Answer 22

alternative splicing

Question 23

atleast one specific what is required per amino acid during translation

Answer 23

tRNA

Question 24

what is the form of tRNA ready to be used in translation; and connects to amino acid

Answer 24

aminoacyl-tRNA

Question 25

used as a signal initiation of translation; how the cell knows this RNA needs to be translated

Answer 25

7-methyl guanosine cap

Question 26

a longer polyA tail means what for translation

Answer 26

most likely to happen

Question 27

Initiation step of translation:

Answer 27

1. binding of methyl cap 2. joining of elF4B 3. 43S complex 4. joining of 60S with 43S at start codon (starts when it hits its first AUG)

Question 28

elongation of translation sites:

Answer 28

A: recruits incoming aminoacyl tRNAs P: growing tRNA (from P to A) E: exit site (for empty tRNA)

Question 29

many mRNAs have multiple _____ bound that allows translation of many proteins

Answer 29

ribosomes

Question 30

this happens when the release factor enters the A site

Answer 30

termination of translation

Question 31

this antibiotic binds to 30S subunit and causes misreading of genetic code; also inhibits initiation

Answer 31

aminoglycoside (streptomycin/gentamicin)

Question 32

this antibiotic binds to 30S acceptor site (A site) and is just in the way

Answer 32

tetracycline

Question 33

this antibiotic binds to 50S subunit and inhibits peptide bond formation

Answer 33

chloramphenicol

Question 34

this antibiotic binds to 50S and blocks transferase reaction (inhibits enzyme that catalyzes formation)

Answer 34

erthromycin

Question 35

this antibiotic binds to A site and acts as peptidyl acceptor- aborting elongation (blocks elongation)

Answer 35

puromycin

Question 36

what blocks translation by inhibiting mTOR (mammalian target of rapamycin); inhibiting elF4E inhibits translation; also prevents blood vessel walls from thickening after angioplasty

Answer 36

rapamycin

Question 37

addition/removal of AA's through signal sequence(marks protein for secretory pathway)/ubiquitination (degradation by proteasome)

Answer 37

post-translational modification

Question 38

4 steps of post-translational modification

Answer 38

1. add/remove AA's 2. add carbohydrates 3. add lipids 4. reversible regulation through chemical modifications

Question 39

what post-translational modification is essential for proper protein folding

Answer 39

N-glycosylation

Question 40

addition of lipids to protein through post-translational modification

Answer 40

myristylation

Question 41

amino acids used in phosphorylation during post-translational modification

Answer 41

Ser Thr Tyr

Question 42

amino acids used in hydroxylation during post-translational modification

Answer 42

pro lys

Question 43

methylation of histones

Answer 43

inhibits transcription

Question 44

acetylation of histones

Answer 44

promotes transcription

Question 45

lowers energy required for transition state (free energy of activation); increases rate of rxn

Answer 45

enzyme

Question 46

rxn speed is increased dramatically when you introduce more ____

Answer 46

substrate

Question 47

this alters enzyme activity and is different in different areas of the body

Answer 47

pH

Question 48

extreme temperatures (high and low) do what to enzymes

Answer 48

inactivate them

Question 49

substrate concentration at 1/2 vmax; similar to ligand concentration needed to occupy 50% of binding sites Measure of AFFINITY

Answer 49

Km; Kd

Question 50

rxn speed is proportional to substrate concentration

Answer 50

first order

Question 51

independent of substrate concentration

Answer 51

zero order

Question 52

drug that competes with HMG-CoA (substrate at the active site); more drug than substrate leads to enzyme activity reduced

Answer 52

statin

Question 53

shift of curve to the right (Km increases-add more substrate to get back to Km)

Answer 53

competitive inhibition

Question 54

inhibitor does not compete with substrate at binding site; amount of active enzyme has decreased (vmax decreases)

Answer 54

noncompetitive

Question 55

example of noncompetitive inhibitor

Answer 55

lead

Question 56

lead being a noncompetitive inhibitor of ferrochelatase impairs heme synthesis and leads to what

Answer 56

anemia

Question 57

inhibitor only binds to enzyme-substrate complex; vmax and Km decrease

Answer 57

uncompetitive enzyme inhibition

Question 58

example of uncompetitive inhibitor (immunosuppressant); inhibits IMP dehydrogenase (B and T cells use this process)

Answer 58

mycophenolate

Question 59

similar to noncompetitive; vmax decreases and Km stays the same

Answer 59

irreversible inhibition

Question 60

organophosphorus pesticides leads to inhibition of acetylcholinesterase= SLUDGEM

Answer 60

irreversible inhibition

Question 61

(drug) proton pump inhibitor; type of irreversible inhibition

Answer 61

omeprazole

Question 62

can change Vmax or Km

Answer 62

allosteric regulators

Question 63

AMP, GMP, IMP are heterotropic what

Answer 63

allosteric inhibitors

Question 64

if IMP, GMP, and AMP are abundant in the cell; what feedback happens

Answer 64

negative

Question 65

how cells even out substrates and products

Answer 65

+ and - feedback loops

Question 66

what reduces DNA synthesis and explains toxicity of increased levels of dATP in adenosine deaminase deficiency

Answer 66

binding of dATP to allosteric sites on enzyme inhibiting enzyme activity

Question 67

all CK in the brain is what isoform

Answer 67

BB

Question 68

all CK in skeletal muscle is what isoform

Answer 68

MM

Question 69

in cardiac muscle, 1/3 of CK is ___ and the rest is_____

Answer 69

MB; MM

Question 70

enzyme indicator that cardio conversion (after myocardial infarction) was successful

Answer 70

MB (returns to normal value-decreases)

Question 71

antibiotic that binds at A site and acts as a peptidyl acceptor

Answer 71

puromycin