Question

Which nutrient produces more ATP under aerobic conditions in an aerobe, a triglyceride with 3X36 carbon fatty acids or 10 glucose molecules? Why?

Answer 1

from a triglyceride with 3 fatty acids having 36 carbon atoms, the triglyceride can be digested to 3, 36 carbon long fatty acids, and one glycerol, glycerol can be used in glycolysis, glycerol is converted to glyceraldehyde 3-phosphate by glycerol kinase, which is then used in glycolysis and yield one ATP, one NADH, and one pyruvate.

A saturated fatty acid with 2n number of carbon atoms undergoes n-1 rounds of beta-oxidation, during one beta-oxidation one NADH and FADH2 is produced, so total of n-1 NADH and n-1 FADH2 are produced from one fatty acid.

here 2n=36

n=18

so number of NADH produced=18-1

= 17

there are three fatty acids, so from beta-oxidation number of NADH produced= 173=51

number of FADH2 produced from 3 fatty acids which are 36 carbon long = 173=51

36 carbon long fatty acid is converted to 18 acetyl CoA, by beta-oxidation, which is then used in the TCA cycle, to produce 3 NADH, one ATP, and one FADH2.

FADH2 and NADH are oxidised by electron transport chain and uses the H+ gradient to synthesize ATP, from one NADH 3 ATPs are produced and from one FADH2 2 ATPs are produced.

so from 18 acetyl CoA

183+ 182+ 18= 108 ATPs are produced

and from 51 NADH and 51 FADH2

513+ 512=255 ATPs are produced

so from 3, 36 carbon long fatty acids

3108 + 255 = 579 ATPs are produced.

and from that glycerol molecule, one ATP is used and one ATP and one NADH is produced, so via glycolysis net yield is one NADH and one pyruvate, pyruvate is oxidized by pyruvate dehydrogenase, one NADH is produced in this reaction, and pyruvate is converted to acetyl CoA, acetyl CoA is used in TCA cycle, and 3 NADH, one ATP, one FADH2 are produced.

so total number of ATP produced from glycerol= 53+21+1= 18

( from one NADH 3 ATPs are produced and from one FADH2 2 ATPs are produced., there are five NADH and one FADH2 and one ATP)

so total number of ATPs produced from a triglyceride with 3X36 carbon fatty acids = 18+ 579= 597

from one glucose 36 ATPs are produced and from 10 glucose molecules 1036= 360 ATPs are produced,

so more ATPs are produced from triglyceride with 3X36 carbon fatty acids.