lactic acid cycle - makes ATP?

[hokie4life]

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in the absence of oxygen, we undergo fermentation to make lactic acid from pyruvate and this used NADH changing it to NAD+ but does it also make ATP? or do we consider it does because the NAD+ it regernerates will make ATP from glycolysis?

in a question it had ATP and lactate OR NAD+ and lactate as options for what pyruvate gets turned into in muslce cells and I put with ATP but I guess NAD+ is a better answer, just am not clear why ATP is not included too as a product?

 

[shoombol tallah]

I'm pretty sure you get 2 net atp through lactate fermentation. Its what muscles use for energy under anaerobic conditions. Also the lactate that is formed from fermentation goes into the Cori cycle. Which means the lactate is transported to the liver where it is turned into pyruvate and finally back into glucose. However NAD+ is also regenerated...to be honest i think the question is written incorrectly because all of those occur during lactate fermentation.

 

[hokie4life]

okay yea we do get ATP for the muscles! so i was right kinda, I guess the answer is with NAD+ and not the ATP one because we're asking what muslces get in the absence of oxygen from converting pyruvate?

we get NAD+ from this but don't we get ATP from the lactic acid fermentation of the lactate so that's why NAD+ is the better answeR?

cuz pyruvate ---> lactate ----> lactic acid

we get NAD+ from the first step but we get ATP from the second right?

 

[D.D.S.]

okay yea we do get ATP for the muscles! so i was right kinda, I guess the answer is with NAD+ and not the ATP one because we're asking what muslces get in the absence of oxygen from converting pyruvate?

we get NAD+ from this but don't we get ATP from the lactic acid fermentation of the lactate so that's why NAD+ is the better answeR?

cuz pyruvate ---> lactate ----> lactic acid

we get NAD+ from the first step but we get ATP from the second right?

In fermentation, you get lactate (lactic acid, same thing) from pyruvate. In the process you generate NAD+, which is used in glycolysis to produce the ATP. The lactate goes to the liver, and the Cori cycle takes place where it is converted into glucose. I remember this question and they are asking about fermentation only. Glycolysis, or Cori cycle in the liver are seperate processes, so dont include them when they are asking about fermentation. Only think of whats going on in fermentation. Hope this helps....

 

[rimmies]

so to boil all that down there is no atp produced in the lactic acid cycle but the results of this anaerobic process gives the items needed to make atp later on....correct?

 

[hokie4life]

okay so no ATP in fermentation....but then where do the muscle cells get their energy from?

 

[saaz55]

okay so no ATP in fermentation....but then where do the muscle cells get their energy from?

okay i think we're having a confusion of terms here. glysolysis is the part where we convert one glucose into 2 pyruvates, a net of 2 ATP, and NADH from NAD+.

since we dont have oxygen present, our muscles go through fermentation, so that we can do glycolysis again. the reason why go through fermentation in the first place and not constantly through glycolysis alone, is because we need to regenerate the NAD+ supply for glycolysis. so we go through fermentation and transform pyruvate (3 carbon) into lactic acid (3-carbon) as well as converting the NADH from the glycolysis into NAD+.

Note: in anaerobic respiration, we do not receive ATP supply from the NADH we get from glycolysis. so dont be confused by this.


All in all, the only energy supply we receive during ANAEROBIC RESPIRATION are the 2 ATP from GLYCOLYSIS. and FERMENTATION only makes 2 NAD+ from NADH (of glycolysis) and transforms pyruvate into lactic acid.

Also know, during ALCoHOL fermentation, we change the 3-carbon pyruvate molecule into a 2-carbon ethanol and one CO2 molecule per pyruvate. PLus, we do the same conversion of NADH to NAD+ as seen in lactic acid fermentation.

I think that should be it. correct me if im wrong in anything

oh and to specifically answer the question, the actual fermentation part does not supply energy. the glycolysis part does. both of these step combined is the anaerobic respiration process.

 

[RyanF]

okay so no ATP in fermentation....but then where do the muscle cells get their energy from?

Well it depends on what muscle fiber types you're talking about (type I, IIa and IIb). The small oxidative fibers will go through oxidative phosphorylation to generate ATP and the larger glycolytic fibers only utilize glycolysis. Muscles can also quickly generate energy by using phosphagens to convert ADP to ATP.

 

[hokie4life]

this was a great explanation. thank you guys!!! 🙂