Biology (Metabolism basics)

Question 1

What do enzymes do?

Answer 1

• speed reactions by lowering activation energy
• do nothing to ΔG
• increase rate of reaction
• enzymes neither changed nor consumed.

Question 2

Michaelis Menton equation

Answer 2

Vmax = max rate of reaction, all active sites filled.

1/2 vmax = Km

Question 3

Inhibition and Michaelis Menton

Answer 3

No inhibition: vmax reached

Competitive inhibitor: vmax reached and Km increases.

Non competitive inhibitor: vmax not reached and Km does change.

Question 4

Effect of temperature and pH on enzyme catalyzed reactions.

Answer 4

Optimal pH and temperature for some enzymes

1) pepsin pH <7 and trypsin pH >7
2) most enzymes work at temperature between 37 to 38 degrees Celsius

• Assume reaction rate will increase by double every 10 degree Celsius increase

Question 5

Allosteric enzyme

Answer 5

2 or more active sites that can have an active form (catalyze reaction) and inactive form (cannot catalyze reaction).
- depends on regulator bound to active site: either an allosteric inhibitor or activator

Cooperativity: binding at one site increases binding at subsequent sites

Question 6

Positive and Negative feedback

Answer 6

Positive feedback is a product encouraging its own production and negative feedback discourages.

Question 7

Zymogens

Answer 7

• Enzymes produced in inactive form.
• Must be cleaved or altered or altered to become active.

Trypsinogen—> Trypsin

Question 8

Autotroph

Answer 8

Convert sunlight into energy stored in glucose

Question 9

Heterotroph

Answer 9

Break down nutrients obtained in diet.

Question 10

Glycolytic Pathway

Answer 10

Convert glucose to ATP

Question 11

Glycolysis

Answer 11

Occurs in cytosol.

Glucose converted into 2 pyruvate
2 NAD+ —> 2 NADH
2 ATP —> 4 ATP ( 2net ATP)

Question 12

Linking Step

Answer 12

• What happens to pyruvate?

2 pyruvate —> 2 Acetyl CoA

• done by Pyruvate decarboxylation
• done in presence of oxygen.
• 2 CO2 and 2 NADH produced

Question 13

Basics of the citric acid cycle

Answer 13

Glucose—> 2 pyruvate—> 2 Acetyl CoA

Occurs in mitochondrial matrix

Citric Acid Cycle takes: Acetyl CoA

• > 3 NADH
• > FADH2
• > 1ATP

1 molecule of Glucose yields 2 turns of citric acid cycle

• > 6 NADH
• > 2FADH2
• > 2 ATP
• > 4 CO2

Question 14

Electron Transport Chain

Answer 14

Occurs in INNER membrane space of mitochondria

Uses FADH2 and NADH and ATP

NADH and FADH2 give up electrons and become oxidized to NAD+ and FADH

Electrons enter and run along inner membrane space and H+ ions get sent into inter membrane space.

Concentration gradient established as higher concentration of H+ in inter membrane space than in mitochondrial matrix.

Embedded in inner membrane is ATP synthase and these H+ ions will go down ATP synthase which will churn out ADP into ATP.

Electrons will travel and final electron accepter is O2. When O2 combined with electrons it creates H2O

If no O2 it goes back to 2 pyruvate

Question 15

Results of cellular respiration

Answer 15

3 ATP for every NADH sent to ETC
-> only 2 ATP from glycolysis

2 ATP for every FADH2 sent to ETC

34 ATP from ETC

Eukaryotes produce 36 ATP total

Question 16

Substrate level phosphorylation vs Oxidative phosphorylation

Answer 16

Substrate level: ATP Generated from glucose oxidation.

Oxidative: ATP Generated from electron carriers in ETC.