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## Class 11 Biology (India)

### Course: Class 11 Biology (India)>Unit 12

Lesson 4: Electron transport system and oxidative phosphorylation

# Calculating ATP produced in cellular respiration

Created by Jasmine Rana.

## Want to join the conversation?

• Is it a good idea to know the reasoning/calculating of ATP production from cellular respiration for the MCAT? I can't see them asking questions this specific, but then again, the exam is changing.
• My book for the 2015 MCAT has a page overviewing the net results of cellular respiration and it also mentions that from NADH 2.5 ATP can be made and from FADH2 1.5 ATP can be made. It also goes into depth about all the electron carrier molecules in the electron transport chain and how many protons it pumps and what subunits make up each complex so I'm assuming anything in this video is fair game for the MCAT
• Wait... If the "max" output, based on the ratios, is 32 ATP's, then where do some books/authors get 38 from? It doesn't even seem possible... Even Sal had a video earlier that mentioned "38" as the most acceptable/appropriate number relative to "standardized tests/questions."
• Easy-peasy. There is a theoretical maximum of 38 ATP produced from a single glucose molecule: 2 NADH produced in glycolysis (3 ATP each) + 8 NADH produced in Krebs cycle (3 ATP each) + 2 FADH2 produced I don't know where (2 ATP each) + 2 ATP produced in the Krebs cycle + 2 ATP produced in glycolysis = 6 + 24 + 4 + 2 + 2 = 38 ATP, theoretically. Hope that helps!
• make a video on the glyoxylate cycle! that would he helpful.
• why does 2 FADH2 produce 6H+ and not 4H+?
• The FADH2 doesn't directly produce the 6 H+ that gets pumped through the complexes. It produces the energy that enables the pumps to pump H+. There are a lot of H+ sources in the intermembrane space so it doesn't have to come from FADH2. Notice that FADH2 enters at complex 2 but the protons are pumped through complexes 3 and 4. This means that FADH2 is only providing the 2 electrons/ energy that travels down the transport chain and is used to pump the protons through.
• so what is it? 30? 32? or 38 ATP total produced? because i know this is always a question on the mcat where they'll ask whats the total amount of ATP produced PER glucose molecule.. so please can someone give me an answer or a justification on whats a safe answer?
• It is a total of 38 ATP produced. You did ask on the total amount of ATP produced per glucose molecule, and that is 38 starting from glycolysis upto ETC. 1 glucose molecule will yield 2 pyruvate that will run in the Kreb's cycle and in the ETC.
• Why are her videos always very long?!
• Hey just a quick question. So if i'm asked "what's the theoretical max yield of ATP per cell" would i say 38 or 36? i.e. to answer that question, do i take into consideration that i spent 2 ATP while shuttling the electrons from the NADH from the cytosol to inner mitochondrial membrane ?