(DSA3) Fundamentals of Biochemical Reactions Flashcards
What does a positive, negative, and 0 value of ΔG indicate?
DSA3 S3 LO1.a.i
Positive ΔG:
-nonspontaneous, requires energy
ΔG=0:
-reaction is at equilibrium
Negative ΔG:
-spontaneous, produces energy
What are the main driving factors of reactions?
DSA3 S5 LO1.a.ii
Mass action (Le Catelier’s principle):
- increasing concentrations of reactants will drive reaction to products (opposite applies as well)
- increasing concentrations of products will drive reaction to reactants (opposite applies as well)
Energy coupling:
-exergonic reactions that have a common intermediate with an endergonic reaction can be used to drive the endergonic reaction if they have a sufficient ΔG
How do the kidneys regulate acid-base balance?
DSA3 LO1.a.iv
The kidneys can remove H+ from the blood as NH4+ and can reabsorb HCO3-
Low Blood pH increases removal H+ and reabsorbtion of bicarb
High pH results in fewer H+ removal and less bicarb reabsorbtion
Describe metabolic acidosis and the compensatory response.
DSA3 S8
Decreased pH/increased [H+] caused by the addition of an acid or loss of HCO3- buffer.
Hyperventilation compensates by reducing [H+] by conversion to H2O and CO2 (which is exhaled)
Describe respiratory acidosis and the compensatory response.
DSA3 S8
Decreased pH/increased [H+] caused by increased CO2 due to hypoventilation.
Renal response will increase HCO3- reabsorption and remove H+ from the blood.
Describe metabolic alkalosis and the compensatory response.
DSA3 S8
Increased pH/decreased [H+] caused by the addition of strong base or loss of strong acid.
Hypoventilation increased CO2 which is converted to H+.
Describe respiratory alkalosis and the compensatory response.
DSA3 S8
Increased pH/decreased [H+] caused by by decreased CO2 due to hyperventilation.
Renal response will decrease HCO3- reabsorption
Differentiate between apoenzymes and holoenzymes.
DSA2 S16
Apoenzymes:
-inactive due to absence of coenzyme
Holoenzymes:
-activated due to bound coenzyme
What is PLP and where does it come from?
DSA3 S17 LO1.b.ii
Pyridoxal phosphate
Coenzyme derived from vitamin B6
What is a catalytic triad and what amino acids are present?
DSA2 S19
Acid: aspartic acid
Base: Histidine
Nucleophile: Serine
What is Km?
DSA2 S30 LO1.c.i
Concentration of substrate at which rate of reaction is 1/2 Vmax.
Inversely related to affinity
Differentiate between competitive, noncompetitive, and uncompetitive inhibition. (Relate change of Km and Vmax)
DSA2 S31-35 LO1.c.ii
Competitive:
- binds at active site
- Km increase (more S outcompetes I)
- Vmax unchanged
Noncompetitive:
- binds at site other than active site
- decreases Vmax (inactivates E so there are less reactions)
- unchanged Km
Uncompetitive:
- binds enzyme-substrate complex
- decrease in Km and Vmax
What medical diagnosis is elevated alkaline phosphatase indicative of?
DSA2 S45 LO1.d.ii
Bone disease
What medical diagnosis is elevated sorbitol or lactate dehydrogenase indicative of?
DSA2 S45 LO1.d.ii
Obstructive liver disease
What medical diagnosis is elevated acid phosphatase indicative of?
DSA2 S45 LO1.d.ii
Prostatic cancer
What medical diagnosis is elevated amylase indicative of?
DSA2 S45 LO1.d.ii
Acute pancreatitis
What medical diagnosis is elevated aldolase or ASH indicative of?
DSA2 S45 LO1.d.ii
Muscular dystrophy
What medical diagnosis is elevated CK- MM indicative of?
DSA2 S45 LO1.d.ii
Liver disorder
oxioreductase
tranasfers eletron from a donor to acceptor
trasnsferases
trasnfer a fuctional group between molecules
isomerases
rearrange/ isomreize molecules
lyases
add or remove atoms to form a double bond
ligasers
form bonds with hydrolysis of atp
hydroases
cleave with water
Cofactor
Small organic molecules, derived from vitamins
-Cosubstrate: temporary association; bind and then detach in altered state•NAD+: loosely associated, leaves in a changed form (reduced)
–Prosthetic: permanent association•FAD: tightly bound, remains in original form ie •Heme
Chromium and iodine are ______-
essential ions, not “cofactors”
Each enzyme has its own optimal ____ and ____.
-temp (ie denatruation) and pH (pepsin)
Gastric proton pump inhibitors
also known as H+/K+ATPase.
•Found in the parietal cells that line the gastric lumen.
•Pump H+ into the lumen where it combines with Cl- to form HCl.
•Conditions like ulcers, indigestion, heartburn require decrease in gastric acid thus proton pump inhibitors are prescribed (Omeprazole, lansoprazole, esomeprazole).
Omeprazole, lansoprazole, esomeprazole
gastric proton pump inhibitors
hypochlorhydria
Reduced HCl production causes hypochlorhydria which can reduce absorption of nutrients, increase in sensitivity to food poisoning, reduction in gastric enzyme efficiency, particularly pepsin, gastric amylase, gastric lipase.
Inhibiton of Metalloenzymes
an enzyme that requires a metallic cofactor: is inhibtied by chealting factors that bind metal ions. EDTA is an example (MN, CU, FE, PB, CO)
Cheating agents for Pb poisioning
Pb inhibits ALA dehydratase and ferrochelatease
-ferrochelatase: is invovled in heme synthesis (coenzyme) of hemogolobin) this will cause lead poisioning
Lead posioning cure
admister Ca EDTA: Pb has a higher affinity for EDTA than CA
Allosteric effector
binds to a site, non covalently, other than the catalytic site
-effetctors can be: positive (activators) or negative (inhibitors)
Isozyme
same catalytic function, different primary sequence. They hav different binding sites
-examples: markers of MI
Troponin in MI
trop has a trimeric strucrure: TN-C, TN-T, and TN-I
- Tn-I has 3 subunits: cTN-I, sTN-I (cardiac and skeletal)
- trops have overtaken tradtional cardiac enzymes for dectection of MI
- max sentivity is 10-24 hours following onset of MI
