Question

This is the answer but I do not understand how it was balanced this way. If someone could leave an explanation that would be great. thanksIj

4. Metabolic pathways tend to use the same types of reactions over and over, so once you learn a few pathways, you can use that knowledge to understand pathways you have never studied. We have also seen that each of the amino acids are catabolized by their own pathway to produce common intermediary metabolites. Below is a description of the pathway for lysine catabolism. Use this to determine what products are made by the catabolism of lysine. It will help to draw the intermediates of the pathway. Write a balance net reaction coupled to ETS/OxPhos. Is lysine glucogenic or ketogenic or both? You should be able to figure this out without looking up the lysine pathway Both amines are converted to carbonyls. In other pathways, the nitrogen atoms will combine with a CO2 to produce one urea and two NADH, consuming 4 ATP. b. The aldehyde is oxidized to a carboxylic acid c. There is a decarboxylation just like in pyruvate dehydrogenase. d. The alkane is oxidized to an alkene Add water to the alkene to make alcohol on the beta carbon f. Decarboxylate again g. Oxidize the alcohol. h. Split the molecule using COASH (The sulfur from COASH attacks the ketone carbon and the rest of the molecule is the leaving group) a e. The pathway makes two molecules of acetyl CoA so it is ketogenic and not glucogenic 4. S-CoA S-CoA СО" COO COO =C H3N- CH 4 ATP CO2 COASH CH2 CH2 CH CH2 CH2 CH2 CH CH2 CH2 CH2 FADH2 CO2 Urea CH2 NADH CH2 CH2 CH2 CH2 NADH 2 NADH CH COO COO COO CH2 NH3 S-CoA S-CoA S-CoA S-CoA COASH C Нао CH3 CH2 CH2 CH2 -CH но CO2 CH но NADH S-CoA CНз СНз CH2 COO CHз The Balance Net Reaction for the pathway above is: Lysine 4 ATP +2 COASH 2 аcetyl-CoA + CО2 + 5 NADH + FADH2 + Urea + 4 ADР, Р: If you use ETS/OxPhos, then you consume 3 O2 and make 14 ATP so the net reaction is: 10 ADP,PiLysine + 2 COASH + 3 O2 _2 acetyl-CoA Urea + 10 ATP CO2 O2 so you get: oA makes 10 ATP and 2 CO2 and consume each the CAC/ETS/ But >5 CO2 + Urea +30 ATP Lysine 7 O2 30 ADP,Pi +

Answer 1

KIndly take a look at the electron transport chain and Krebs cycle/ TCA cycle for better understanding.

First, consider the balanced equation,

The Balance Net Reaction for the pathway above is: Lysine 4 ATP 2 COASH - 2 acetyl-CoA +CO2 5 NADH + FADH2 + Urea + 4 ADP,Pi

5 molecules of NADH, 1 molecule of FADH₂ and 4 molecules of ADP; Pi are formed.

Now, in the electron transport chain (ETC/ETS) each molecule of NADH will be oxidized to NAD⁺ and it will produce 2.5 molecules of ATP and each molecule of FADH₂ will produce 1.5 ATP and the terminal electron acceptor oxygen will consume the electrons and will be reduced to H₂O.

So, if we consider ETS, 5 NADH and 1 FADH₂ will produce a total of (5*2.5) + 1.5 = 14 ATP and 6 oxygen atom or 3 oxygen molecule will be reduced to 6 H₂O.

Now, as the reaction has already utilised 4 ATP, the total ATP gain = 10 ATP.

So, we can write the reaction in the following way.

If you use ETS/OxPhos, then you consume 3 O2 and make 14 ATP so the net reaction is: 10 ADP,Pi Lysine 2 COASH 3 O2_ 2 acetyl-CoA + CO2 + Urea + 10 ATP

Now, 2 acetyl-CoA will be oxidized. First, by the TCA cycle, each acetyl-CoA will be oxidized and will produce 3 NADH, 1 FADH₂, 1 GTP, and 2 CO₂.

Now by the ETS, 3 NADH and 1 FADH₂ will produce a total of (2.5*3) + 1.5 = 9 ATP and 2 molecules of O₂ will be reduced. 1 GTP will give rise to 1 ATP. So, a total of 10 ATP will produce by the complete oxidation of 1 acetyl-CoA.

So, by the complete oxidation of 2 acetyl-CoA, 20 ATP and 4 molecule of CO₂ will be produced and 4 molecules of O₂ will be reduced.

So, the total reaction will become,

But using the CAC/ETS/OxPhos, each acetyl-CoA makes 10 ATP and 2 CO2 and consumes 2 O2 so you get: >5 CO2 + Urea + 30 ATP 30 ADP,PiLysine + 7 O2