Proteins, Enzymes, Membranes and Signal Transduction EC

Question 1

Cystinuria

Answer 1

Autosomal Recessive
Defect in basic amino acid transporter (Cystine, Lysine, Arginine) in renal tubules
Excessive excretion and formation of cystine kidney stones

Question 2

Hartnup’s Disease

Answer 2

Autosomal Recessive
Pellagra like (diarrhea, dermatitis, dementia)
Defective absorption of tryptophan

Question 3

Gs Receptor function and coupled receptors

Answer 3

Stimulate Adenylate Cyclase (increase cAMP –> PKA)

Dopamine (D1)
Epinephrine (B1,B2)
Glucagon histamine (H2)
Vasopressin (V2)

Question 4

Gi Receptor function and coupled receptors

Answer 4

Inhibit adenylate cyclase (decrease cAMP)

Dopamine (D2)
Epinephrine (a2)

Question 5

Gq Receptor function and coupled receptors

Answer 5

Stimulates phospholipase C (increased IP3 & DAG)

Angiotensin II
Epinephrine (a1)
Oxytosin
Vasopressin (V1)

phosphorylated myosin light chains –> SM contraction

Question 6

Gt receptor function and coupled receptors

Answer 6

Stimulate cGMP phosphodiesterase (increase cGMP)

Rhodopsin (light sensitive)

Question 7

Tyrosine Kinase overview (insulin receptor as example)

Answer 7

Insulin binds TK–> autophosphorylation
IRS-1 activates . . .
RAS/MAP kinase (long-term effects-gene expression) and
PKB (short term effects-increased GLUT-4)

Question 8

Cholera/EHEC toxins

Answer 8

Permanently activate Gs (ADP-ribosylation)
Increased cAMP
Loss of isotonic fluid
Diarrhea

Question 9

Pertussis toxin

Answer 9

Permanently inactivates Gi (ADP-ribosylation)
Increased cAMP
Increased mucus secretion in respiratory tract (whooping cough)

Question 10

Ephedrine MOA and use

Answer 10

alpha-1 agonist

Vasoconstriction (decongestant)

Question 11

Albuterol and Terbutaline MOA and use

Answer 11

Beta-2 agonists

Bronchodilation (asthma)

Question 12

Beta blockers MOA and use

Answer 12

decrease BP

precipitate asthma

Question 13

Losarton MOA and use

Answer 13

Angiotensin II antagonist

Lowers BP

Question 14

Chlorpromazine/Haloperidol MOA and use

Answer 14

D2 antagonists

Antipsychotics

Question 15

Niacin as a co-enzyme

Answer 15

NAD+ (nicotine adenine dinucleotide) 
REDOX reactions (ie. glycolytic pathway)

Question 16

Pyridoxine as a co-enzyme

Answer 16

Pyridoxal phosphate
TRANSAMINATION reactions (ie. alanine to pyruvic acid)

Question 17

Thiamine as a co-enzyme

Answer 17

DECARBOXYLATION (ie. degradation of branched chain amino acids)

Transketolase (2-carbon transfer in pentose-phosphate-pathway)

Question 18

Biotin as a co-enzyme

Answer 18

CARBOXYLATION

Question 19

Folic acid as a co-enzyme

Answer 19

THF (tetra-hydro-folate)

One carbon transfers (ie. serine –> glycine)

Question 20

Magnesium as co-factor

Answer 20

Kinases

Question 21

Zinc as a co-factor

Answer 21

Carbonic anhydrase
Collagen
Alcohol dehydrogenase
Superoxide dismutase

Question 22

Copper as a co-factor

Answer 22

Oxidases (lysyl oxidase in collagen cross-linking)
Ferroxidase (Fe3+–>Fe2+)
Cytochrome c oxidase (electrons to O2 to make water)

Question 23

Iron as a co-factor

Answer 23

Cytochromes

Question 24

Selenium as a co-factor

Answer 24

Glutathione peroxidase

Question 25

Zero-Order Reaction

Answer 25

Velocity independent of [Substrate] Saturated

Question 26

First-Order Reaction

Answer 26

Velocity dependent on [Substrate] Below Km

Question 27

Alanine aminotransferase (ALT) diagnostic use

Answer 27

Viral hepatitis (ALT>AST)

Question 28

Aspartate aminotransferase (AST) diagnostic use

Answer 28

Alcoholic hepatitis (AST>ALT) MI (AST only)

Question 29

Alkaline phosphatase diagnostic use

Answer 29

Osteoblastic bone disease Metastatic prostate cancer Obstructive liver disease

Question 30

Amylase diagnostic use

Answer 30

``` Acute pancreatitis (lipase more specific) Mumps (parotitis) ```

Question 31

Creatine Kinase (CK) diagnostic use

Answer 31

MI (CK-MB) | DMD (CK-MM)

Question 32

gamma-glutamyl transferase (GGT) diagnostic use

Answer 32

Obstructive liver disease | Alcoholics (increased)

Question 33

Lactate dehydrogenase (LDH)

Answer 33

MI

Question 34

Lipase

Answer 34

Acute pancreatitis (more specific than amylase)

Question 35

What form of Fe binds O2?

Answer 35

Fe2 binds O2

Question 36

What is methemoglobin?

Answer 36

Hgb with Fe3+ | CANNOT BIND O2

Question 37

What does a left shift in the O2 binding curve mean?

Answer 37

Increased Hgb affinity for O2 (loading)

Question 38

What does a right shift in the O2 binding curve mean?

Answer 38

Decreased Hgb affinity for O2 (UNloating) ``` Causes: decreased O2 binding 2,3 BPG (response to high altitude) H+/CO2 Increased tempterature ```

Question 39

What is the mechanism by which CO2 effects hemoglobin binding?

Answer 39

Conversion by carbonic anhydrase decreases pH Protonation of histidine residues DECREASED AFFINITY FOR O2

Question 40

Slate grey cyanosis in infant without pulmonary or cardiac disease

Answer 40

Hereditary methemoglobinemia (HgM)