(DSA3) Fundamentals of Biochemical Reactions

Question 1

What does a positive, negative, and 0 value of ΔG indicate?

DSA3 S3 LO1.a.i

Answer 1

Positive ΔG:
-nonspontaneous, requires energy

ΔG=0:
-reaction is at equilibrium

Negative ΔG:
-spontaneous, produces energy

Question 2

What are the main driving factors of reactions?

DSA3 S5 LO1.a.ii

Answer 2

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

Question 3

How do the kidneys regulate acid-base balance?

DSA3 LO1.a.iv

Answer 3

The kidneys can remove H+ from the blood as NH4+ and can reabsorb HCO3-

Question 4

Describe metabolic acidosis and the compensatory response.

DSA3 S8

Answer 4

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)

Question 5

Describe respiratory acidosis and the compensatory response.

DSA3 S8

Answer 5

Decreased pH/increased [H+] caused by increased CO2 due to hypoventilation.

Renal response will increase HCO3- reabsorption and remove H+ from the blood.

Question 6

Describe metabolic alkalosis and the compensatory response.

DSA3 S8

Answer 6

Increased pH/decreased [H+] caused by the addition of strong base or loss of strong acid.

Hypoventilation increased CO2 which is converted to H+.

Question 7

Describe respiratory alkalosis and the compensatory response.

DSA3 S8

Answer 7

Increased pH/decreased [H+] caused by by decreased CO2 due to hyperventilation.

Renal response will decrease HCO3- reabsorption

Question 8

Differentiate between apoenzymes and holoenzymes.

DSA3 S16

Answer 8

Apoenzymes:
-inactive due to absence of coenzyme

Holoenzymes:
-activated due to bound coenzyme

Question 9

What is PLP and where does it come from?

DSA3 S17 LO1.b.ii

Answer 9

Pyridoxal phosphate

Coenzyme derived from vitamin B6

Question 10

What is a catalytic triad and what amino acids are present?

DSA3 S19

Answer 10

Acid: aspartic acid

Base: Histidine

Nucleophile: Serine

Question 11

What is Km?

DSA3 S30 LO1.c.i

Answer 11

Concentration of substrate at which rate of reaction is 1/2 Vmax.

Inversely related to affinity

Question 12

Differentiate between competitive, noncompetitive, and uncompetitive inhibition. (Relate change of Km and Vmax)

DSA3 S31-35 LO1.c.ii

Answer 12

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

Question 13

What medical diagnosis is elevated alkaline phosphatase indicative of?

DSA3 S45 LO1.d.ii

Answer 13

Bone disease

Question 14

What medical diagnosis is elevated sorbitol or lactate dehydrogenase indicative of?

DSA3 S45 LO1.d.ii

Answer 14

Obstructive liver disease

Question 15

What medical diagnosis is elevated acid phosphatase indicative of?

DSA3 S45 LO1.d.ii

Answer 15

Prostatic cancer

Question 16

What medical diagnosis is elevated amylase indicative of?

DSA3 S45 LO1.d.ii

Answer 16

Acute pancreatitis

Question 17

What medical diagnosis is elevated aldolase or ASH indicative of?

DSA3 S45 LO1.d.ii

Answer 17

Muscular dystrophy

Question 18

What medical diagnosis is elevated CK- MM indicative of?

DSA3 S45 LO1.d.ii

Answer 18

Liver disorder