Cellular respiration

Question 0

Electron shuttles

Answer 0

NADH & FADH2

Question 1

Cellular respiration overall process

Answer 1

• Organic compounds+O2 -> CO2 + H2O + energy.
• Energy released as electrons go from organic compounds to O2
• C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP + heat)
• Oxidation C6H12O6 -> 6 CO 2
• Reduction: 6 O2 -> 6 H2O

Question 2

Overview of cellular respiration

Answer 2

1. Glycolysis.
2. Oxidation of pyruvate.
3. Krebs cycle
4. ETC & oxidative phosphorilation

Question 3

Overview of glycolysis #1

Answer 3

In cytoplasm.

glucose -> 2x pyruvate (3 carbons) + 2ATP + 2NADH

Question 4

Overview of oxidation of pyruvate #2

Answer 4

Mitochondria.
pyruvate -> acetyl CoA + 2O2 + NADH

per glucose 2 acetyl CoA + 2 O2 + 2NADH

Question 5

Overview of Krebs cycle #3

Answer 5

Mitochondrial matrix.
Acetyl CoA + 2 CO2 + ATP + 3 NADH + FADH2

per glucose 4 CO2 + 2 ATP + 6 NADH + 2 FADH2

Question 6

Overview of ETC & oxidative phosphorilation

Answer 6

Inner mitochondrial membrane.
O2 driving force, electronegative.
30-32 ATP/glucose.

Question 7

ATP production

Answer 7

1. Oxidative phosphorylation (ATP synthase): ADP + Pi = ATP
   - 85% of cellular ATP (26-28 moles)
2. Substrate level phosphorylation: substrate-phosphate + ADP -> ATP + product
   - glycolysis and the Krebs cycle

Question 8

Phases of glycolisis #1

Answer 8

Energy requiring & energy producing (4 ATP & 2 NADH).

Question 9

Energy requiring glycolysis (1)

Answer 9

• Glucose -> 2x glyceraldehyde-3-phosphate.
• ATP hydrolized & phosphorylated intermediate.
• 2ATP:glucose-> glucose-6-phosphate (step #1)
• fructose 6-phosphate -> fructose 1,6-bisphosphate (step #3)

Question 10

Energy producing glycolysis (2)

Answer 10

Glyceraldehyde 3-phosphate -> pyruvate.
1. 4ATP: substrate level phosphorylation
1,3-bisphosphate -> 3phosphoglycerate (step 7)
phosphoenolpyruvate -> pyruvate (3C)
2. NADH: glyceraldehyde-3-phosphate -> 1,3-bisphosphoglycerate (step 6)
Net glucose: 2ATP (final - what we put in), 2 NADH, 2 pyruvate

Question 11

Oxidation of pyruvate to AcetylCoA #2

Answer 11

Pyruvate is transported into the mitochondria.

pyruvate -> CO2 + NADH + AcetylCoA (CoA: coenzyme A)

Question 12

Krebs cycle function #3

Answer 12

Oxidizes AcetylCoA to CO2

Complete oxidation of glucose requires two turns of the cycle

Question 13

Krebs cycle: electrons are passed to..

Answer 13

a. NAD+ ➡️NADH (steps 3,4,8)
isocitrate ➡️ alpha-ketoglutarate
alpha-ketoglutarate ➡️succinyl CoA
malate ➡️ oxaloacetate
b. FAD ➡️ FADH2 (step 6)
succinate ➡️ fumarate

Question 14

Krebs cycle: ATP is produced (step 5)

Answer 14

succinyl CoA ➡️ succinate

GTP ➡️ GDP, ADP-ATP

Question 15

Electron transport chain is comprised of:

Answer 15

• 4 multiprotein complexes (integral membrane proteins)

- 2 mobile electron carriers (shuttles, electrons drop in free energy as they travel down chain)

Question 16

What does the Electron Transport Chain generate?

Answer 16

A proton gradient which is used to produce ATP (does not do it directly, it provides the potential energy)

Question 17

NADH steps in ETC (1-3)

Answer 17

• Complex I receives electrons form NADH, pumps protons from the mitochondrial matrix into the intermembrane space.
• Ubiquinone receives electrons from Complex I: non protein that moves in lipid bilayer.
• Complex III receives electrons from Coenzyme Q: comprised of cytochromes, containing copper. pumps protons from the mitochondrial matrix into the intermembrane space.

Question 18

NADH steps in ETC (4-6)

Answer 18

• Cytochrome receives electrons from Complex III (mobile carrier)
• Complex IV (cytochrome oxidase) receives electrons from cytochrome C: contains a heme prosthetic group containing copper. Pumps protons from the mitochondrial matrix into the intermembrane space.
• Electrons are transferred to oxygen producing water: produce and electrochemical gradient.

Question 19

FADH in ETC

Answer 19

Lower free energy, electrons are at a lower energy point.

Complex 2➡️ubinquinone.