Cellular Respiration

Question 1

Cellular Respiration (defn)

Answer 1

ATP-generation process.

C₆H₁₂O₆ + 6O₂ -> 6CO₂ + 6H₂O + Energy

Question 2

Aerobic Respiration

Answer 2

occurs in the presence of oxygen; three steps:

1. Glycolysis
2. Krebs Cycle (TCA)
3. Oxidative Phosphorlyation

Question 3

Glycolysis

Answer 3

decomposition (lysis) of glucose into pyruvate/pyruvic acid; occurs in the cytosol.

1 Glucose -> 2 pyruvates + 2NADH + 2ATP (net 4 generated - 2 used)

Question 4

Glycolysis (4 steps)

Answer 4

1. 2 ATP added; first several steps require energy input.
2. 2 NADH are produced; NADH is a coenzyme and forms when NAD⁺ combines with two energy-rich electrons and H⁺. NADH is an energy-rich molecule.
3. 4 ATP is produced.
4. 2 Pyruvates are formed.

Question 5

Krebs Cycle

Answer 5

changes pyruvates from glycolysis; also known as tricarboxylic acid (TCA) cycle.

Question 6

Krebs Cycle (2 steps)

Answer 6

1. Pyruvate to acetyl CoA: pyruvate combines with coenzyme A (CoA) to produce acetyl CoA, 1 NADH, 1 CO₂

Pyruvate -> Acetyl CoA + 1 NADH + 1 CO₂

2. Acetyl CoA to coenzymes: acetyl CoA combines with oxaloacetate to form citrate; produces 3 NADH, 1 FADH₂, 1 H₂O, 1 ATP

Acetyl CoA -> 3 NADH + 1 FADH₂ + 1 H₂O + 1 ATP

Question 7

Oxidative Phosphorylation

Answer 7

extract ATP from NADH and FADH₂ through the electron transport chain (ETC).

1 NADH -> 3 ATPs

1 FADH₂ -> 2 ATPs

Question 8

Total number of ATPs produced in Cellular Respiration

Answer 8

Glycolysis: 2 NADH, 2 ATP

Krebs: 2X(1 NADH + 3 NADH + 1 FADH₂ + 1 ATP) = 8 NADH + 2 FADH₂ + 2 ATP

Oxidative Phosphorylation:

10 NADH : 30 ATPs

2 FADH₂ : 4 ATPs

4 ATPs

Total: 38 ATPs

(mitochondrial inefficiency results in ~30 ATPs)

Question 9

Mitochondria

Answer 9

where Krebs cycle and oxidative phosphorylation occur

Question 10

Mitochondria’s 4 areas

Answer 10

1. Outer membrane: phospholipid bilayer
2. Intermembrane area: where H⁺s accummulate
3. Inner membrane: also phospholipid bilayer, consists of cristae/folds, where electron transport chain remove H⁺s from NADH and FADH₂ and transports to the intermembrane area using proteins, ATP synthase also phosphorylates ADP to ATP.
4. Matrix: fluid inside inner membrane, where Krebs and pyruvate -> acetyl CoA transformation occur.

Question 11

Chemiosmosis

Answer 11

process of energy storage in the form of potentail energy created by the proton concentration gradient.

Question 12

Chemiosmosis (5 steps)

Answer 12

1. Krebs cycle produces NADH and FADH₂
2. Electrons are removed from NADH and FADH₂
3. H⁺ ions are transported from matrix to intermembrane space via protein complexes
4. A pH and electrical gradient across the inner membrane is created and provides potential energy.
5. ATP synthase generates ATP: this channel protein allows protons to flow from intermembrane to matrix; this proton movement generates energy for ATP synthase to phosphorylate ADP to ATP.

Question 13

Two types of phosphorylation

Answer 13

1. substrate level phosphorylation: ADP phosphorylated to ATP using energy from the substrate molecule containing the phosphate; occurs in glycolysis
2. oxidative phosphorylation: ADP phosphorylated to ATP using energy from electrons of the ETC; energy generates H⁺ gradient which supplies energy to ATP synthase to generate ATP from ADP and a phosphate group.

Question 14

Anaerobic Respiration (2 types)

Answer 14

cellular respiration in the absence of oxygen; occurs in cytosol; goal is to produce NAD⁺ to promote glycolysis.

1. Alcohol fermentation: occurs in plants, fungi (yeasts), and bacteria
   1) pyruvate -> acetaldehyde + CO₂
   2) Acetaldehyde + NADH -> NAD⁺ + EtOH
2. Lactic Acid fermentation: most lactate/lactic acid transported to liver where it is converted to glucose for use.
   1) pyruvate + NADH -> NAD⁺ + lactic acid