Question

BioAccounting:

The following questions refer to the complete oxidation of one GAP molecule to CO2 by using the central pathways. Fill in each blank with the correct integer value.

1. How many reaction steps lead to a NADH molecule from one GAP? 5

2. How many reactions steps lead to a QH2 molecule from one GAP? 1

3. How many ATP and GTP molecules (combined) are obtained directly from one GAP? 3

4. How many total ATP equivalents are obtained from oxidation of one GAP molecule?  17

So, I know that these are the correct answers because my teacher filled them in on the exam; my question is HOW do we get these answers? The more detail the better, thanks!

Answer 1

1) GAP ( glyceraldehyde 3 phosphate) is produced in the glycolysis. This GAP molecules complete the glycolysis and form pyruvate. This pyruvate by the PDH complex form acetyl coA. Later thos acetyl co A enter in to TCA cycle and lead to complete oxidation of acetyl coA in to Co2.

Path is GAP---- pyruvate--- acetyl co A-- TCA cycle release c02

During these process 5 NADH are released 1 in glycolysis , 1at PDH reaction and 3 in TCA cycle. I am mentioning this enzyme below

Glyceraldehyde 3 phosphate dehydrogenase, glycolysis

Pyruvate dehydrogenase, PDH reaction

Isocitrate dehydrogenase

Alpha keto gluterate dehydrogenase

Malate dehydrogenase, these 3 in TCA cycle

So total 5 NADH is released.

3) total ATP and GYP released

3 no steps are mentioned below, 2 during glycolysis and 1 in TCA cycle

Phospho glucose mutase step

Pyruvate kinase step , these two are of glycolysis

Succinyl thiokinase release GTP , in TCA cycle.

4) total ATP released

For calculations 1NADH= 2.5 ATP

1FADH2= 1.5 ATP

-- GAP in glycolysis release

1NADH = 2.5 ATP

2 ATP

Total 4.5 ATP

--In PDH reaction

1 NADH = 2.5 ATP

--- in TCA cycle

3 NADH - 7.5 ATP

1 FADH2 = 1.5 ATP

1GTP/ ATP

Trial ATP in TCA cycle is10 ATP

Total ATP glycolysis + PDH + TCA

= 4.5+ 2.5+ 10= 17 ATP