respiration

Question 1

Describe the stages of
glycolysis in aerobic respiration

Answer 1

In the cytoplasm of cells:
Glucose is phosphorylated to glucose phosphate using 2 ATP molecules.

2. Glucose phosphate splits into two triose phosphate
3. TP is oxidised to pyruvate making 2 ATP and 1 reduced NAD(EACH)

net gain of 2 ATP and 2 reduced NAD

Question 2

Describe the stages of the link reaction in aerobic respiration.

Answer 2

Pyruvate is actively transported into the mitochondrial matrix.

oxidation of pyruvate (3C) into acetate (2C), producing reduced NAD.
loss of carbon dioxide in the process.
Acetate combines with coenzyme A to produce acetylcoenzyme A

Question 3

Describe the stages of the krebs cycle in aerobic respiration

Answer 3

For both acetyl coenzyme A (from one glucose) in the matrix:

Acetyl coenzyme A reacts with a four-carbon molecule, releasing coenzyme A and producing a 6C molecule. oxidation of 6C molecule to 5C molecule producing reduced NAD. loss of CO2 in the process.
oxidation of 5C molecule back to 4C molecule producing 2 reduced NAD and reduced FAD. loss of CO2 in the process.
ATP generated by substrate-level phosphorylation.

Question 4

Describe the stages of oxidative
phosphorylation in aerobic
respiration

Answer 4

Chemiosmotic theory at inner mitochondrial membrane:

1. reduced NAD and reduced FAD from previous steps release their H
   H -> H+ + e-
2. Electrons pass through ETC by a series of redox reactions.
3. Energy released used to pump H+ (protons) across inner mitochondrial membrane into intermembrane space.
4. H+ ions diffuse down electrochemical gradient, through ATP synthase embedded in the membrane, back into the matrix.
5. ATP synthase catalyses ATP by condensing ADP and Pi in oxidative phosphorylation.
6. O2 acts a terminal electron acceptor from ETC producing water

Question 5

Describe anaerobic
respiration in humans

Answer 5

In the cytoplasm of cells:
Glucose is phosphorylated to glucose
phosphate using 2 ATP molecules.
2. Glucose phosphate splits into two triose phosphate
3. Dehydrogenase catalyses the oxidation of Triose phosphate into pyruvate with a net gain of 2 ATP and a reduced NAD.
Pyruvate reduced by NADH to lactate.
-this regenerates NAD.
-NAD used in glycolysis

Question 6

Describe anaerobic
respiration in yeast/
plants/ microbes

Answer 6

In the cytoplasm of cells:
Glucose is phosphorylated to glucose
phosphate using 2 ATP molecules.
2. Glucose phosphate splits into two triose
phosphate
3. Dehydrogenase catalyses the oxidation of Triose phosphate into pyruvate with a net gain of 2 ATP and a reduced NAD.
Pyruvate reduced by NADH to ethanol
and CO2.
-this regenerates NAD.
-NAD used in glycolysis

Question 7

what does the enzyme dehydrogenase do

Answer 7

removes H from a molecule and adds it to NAD to make reduced NAD