Question

Describe how many ATP are synthesized from the oxidation of one glucose molecule. Include which processes product ATP and how many are made per each NAOH and FADH,? How does this number compare with the number of ATP made from the breakdown of one 16 carbon fatty acid? On o biochemical level, why do we breathe? Make sure to consider the change from the anaerobe to aerobic environment Fumerate can be produced from two different metabolic cycles. Name these cycles and state which cycle would be producing more fumerate in a person with a high protein diet.

Answer 1

13. While calculation energy yield for the complete oxidation of 1 molecule of glucose, one should include the ATP formed by the oxidation of 2 pyruvate molecules to 2 acetyl CoA mols, catalysed by the pyruvate dehydrogenase enzyme system, as this step links the glycolytic pathway with the citric acid cycle.

Glycolysis 8 ATP

Conversion of pyruvate to acetyl-CoA 6 ATP

Citric acid cycle 24 ATP

Total 38 ATP

A	Glycolysis
1.	Glucose + ATP $\rightarrow$ Glucose-6-phosphate	1
2.	Fructose-6-phosphate + ATP $\rightarrow$ Fructose -1,6-diphosphate	1
3.	Reoxidation of 2(NADH +H+) formed in reaction catalysed by glyceraldehyde-3-phosphate dehydrogenase, in the respiratory chain		6
4.	2(1,3-diphosphoglyceric acid) $\rightarrow$ 2(3-phosphoglyceric acid)		2
5.	2(phosphoenol pyruvic acid) $\rightarrow$ 2(enolpyruvic acid)		2

Total -2 10 = 8

B.Oxidation of 2 pyruvate to 2 acetyl CoA yields 6 ATP mols.

C. Citric acid cycle

Reactions catalysed by	Method of production of ATP	Number of ATP produced
Isocitrate dehydrogenase	Oxidation of 2(NADH + H+) in the respiratory chain	6
$\alpha$ -ketoglutarate dehydrogenase	Oxidation of 2(NADH + H+) in the respiratory chain	6
Succinate thiokinase	Oxidation of substrate level	2
Succinate dehydrogenase	Oxidation of FADH2 in the respiratory chain	4
Malate dehydrogenase	Oxidation of 2(NADH + H+) in the respiratory chain	6
	Total	24

ATP yield of 16 C Fatty acid oxidation

Complete degradation of palmitate (C16:O) in _$\beta$ -oxidation generates 35 ATP molecules from oxidation of NADH and FADH2 produced directly and 96 ATPs from the breakdown of the acetyl CoA molecules in the citric acid cycle. However, two ATP equivalents are required to activate the palmitate to its acyl CoA derivative prior to oxidation. Thus, the net yield is 129 ATPs.

15. (i) Fumarate is formed in the citric acid cycle, on dehydrogenation of succinate

(ii) Fumarate is formed by the degradation of amino acids such as Phenylalanine, Tyrosine and Aspartate

More fumarate would be formed by the second step