Respiration

Question 1

Aerobic respiration equation

Answer 1

6O2 + C6H12O6 -> 6CO2 + 6H2O

Question 2

Steps of glycolysis

Answer 2

• activation of glucose by phosphorylation (ATP)
• splitting of phos. glucose into 2x triose phosphate
• oxidation of triose phosphate (loses 2H to NAD)
• production of ATP, leaving pyruvate mols

Question 3

Yield from one glucose mol undergoing glycolysis

Answer 3

2x ATP (2 in, 4 out)
2x NADH
2x pyruvate

Question 4

Equation for the link reaction

Answer 4

pyruvate + NAD + CoA -> acetyl CoA + NADH + CO2

pyruvate oxidised to acetate then acetate 2c combines w coA to form acetyl coA

Question 5

Where does link reaction take place and how many times?

Answer 5

Pyruvate actively transported to mitochondria matrix.
Happens twice for every glucose mol.

Question 6

Krebs cycle

Answer 6

2C acetyl CoA undergoes series of redox reactions after combining w/ 4C, substrate level phosphorylation occurs + reduction of coenzymes

Question 7

What are coenzymes?

Answer 7

molecules that enzymes need to function, act as H carriers eg. NAD, FAD

Question 8

Products of krebs cycle

Answer 8

• 1 mol. of ATP
• 2 mols. of CO2
• x3NADH, FADH(2)

Question 9

Why is Krebs cycle important?

Answer 9

• breaks down large mols into smaller ones
• produces coenzymes (carry e-, p+)
• cyclical, can continue
• produces other useful compounds

Question 10

Oxidative phosphorylation

Answer 10

Occurs in cristae of mitochondria
- NADH donates H
- e- from H undergoes redox reactions on ETC
- electron carriers act as proton pump creating high conc. of H+ in intermembrane space
- chemiosmosis as H+ flow through ATP synthase -> ATP formed
- oxygen accepts e- and p+
-

Question 11

Why is oxygen so important in oxidative phosphorylation?

Answer 11

Acts as final acceptor for e- and p+
O2 + 4e- + 4H+ -> 2H2O
else electrons + protons would back up along chain causing respiration to come to a halt

Question 12

Benefit of oxidative phosphorylation

Answer 12

Energy is released in stages through transfer chain so less is wasted as heat

Question 13

Oxidative phos. in lipids

Answer 13

• hydrolysed to glycerol + f.acids
• phosphorylated + converted to triose phosphate
• f.acid broken down to 2 carbon fragments -> acetyl CoA
• produces many H atoms used to create ATP (double energy of carbs)

Question 14

Oxidative phos. in proteins

Answer 14

• hydrolysed into amino acids which are deaminated
• enter respiratory pathway

Question 15

Anaerobic respiration equations

Answer 15

Fungi + plants: pyruvate + NADH -> ethanol + CO2 + NAD
Animals: pyruvate + NADH -> lactate + NAD

Question 16

Implications of no oxygen

Answer 16

O2 does not accept e- and p+ in ox. phos. so ETC stops -> ATP synthase stops so NAD + FAD not regenerated, Krebs + Link stop
ATP only produced in glycolysis

Question 17

What happens in anaerobic respiration

Answer 17

Some plants, fungi + bacteria: pyruvate accepts H from NADH + loses a CO2
Animals: pyruvate accepts a H from NADH, lactate converted back to pyruvate or glycogen when O2 present

Question 18

Problems with lactate

Answer 18

• causes muscle fatigue, cramps
• acid so changes pH affecting enzymes
• net yield of 2 ATP ols per glucose