book 2 (aerobic respiration)

Question 1

outline the process of glycolysis (location, raw products used and products formed)

Answer 1

1. it occurs in the cytosol
2. each glucose molecule is broken down into 2 molecules of pyruvate
3. there is a net gain of 2 ATP from substrate-level phosphorylation
4. 2 NAD+ molecule is reduced to 2 NADH via dehydrogenation which will be used in oxidative phosphorylation

Question 2

the net gains of glycolysis

Answer 2

2 ATP, 2 NADH and 2 molecules of pyruvate

Question 3

outline the process of link reaction (location, raw products used and products formed)

Answer 3

1. the pyruvate produced from glycolysis enters the mitochondrial matrix from cytosol by active transport via transport protein
2. pyruvate undergoes decarboxylation whereby 1 CO2 molecule is produced and exhaled out from the lungs
3. NADH produced from dehydrogenation to be used in oxidative phosphorylation – catalysed by pyruvate dehydrogenase
4. the remaining 2 carbon fragment reacts with coenzyme A to from acetyl coA to be used in Krebs cycle

Question 4

the net gains of link reaction

Answer 4

2 CO2, 2 NADH and 2 molecules of acetyl coA

Question 5

outline the process of Krebs cycle (location, raw products used and products formed)

Answer 5

1. occurs in the mitochondrial matrix
2. 1 molecule of acetyl coA undergoes oxidative decarboxylation
3. the CO2 produced by decarboxylation is being exhaled from lungs
4. NADH & FADH2 produced from dehydrogenation are used for oxidative phosphorylation
5. 2 ATP are formed from substrate-level phosphorylation
6. oxaloacetate is regenerated to combine with more acetyl coA

Question 6

the total net gains of Krebs cycle

Answer 6

for 1 molecule of glucose – 4 CO2, 2 ATP, 6 NADP, 2 FADH2, 2 oxaloacetate

Question 7

outline the process of oxidative phosphorylation (location, raw products used and products formed)

Answer 7

1. NADH and FADH2 generated from the first 3 reactions transfer it’s hydrogen atom to a series of electron carriers in the electron transport chain, located in the inner mitochondrial matrix
2. NADH and FADH2 are oxidised to regenerate NAD+ and FAD for use in glycolysis, link reaction, and Krebs cycle.
3. during oxidation, the hydrogen atom splits into it’s constituent hydrogen ions and electrons
4. the high energy electrons are transferred to the electron carriers while the H+ proton remains in the mitochondrial matrix
5. the electrons are passed down the electron carriers with increasing electronegativity and decreasing energy levels until it reaches the final electron acceptor, O2, which then recombines with protons to form water. This reaction is catalysed by oxidase cytochrome
6. energy is released during the transfer of electrons along the electron carriers via redox reactions
7. the energy is used to pump protons from mitochondrial matrix into the intermembrane space as mitochondria inner membrane is impermeable to H+
8. this generates a proton gradient across the inner mitochondrial matrix
9. protons diffuse back into the mitochondrial matrix from the intermembrane space, via ATP synthase complex, down a concentration gradient
10. ATP synthase enzyme catalyses the synthesis of ATP from ADP and Pi, using the proton motive forces
11. this process is called chemiosmosis

Question 8

the net gains of oxidative phosphorylation

Answer 8

water molecule, 34 ATP