DAT Achiever...Biology Question.....Please help with these questions....

[Toothguy80]

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So there is this question in DAT achiever that says that all of these are true:

a) Substrate level phosphorylation occurs in glycolysis and the Kreb's cycle.
b) Glycolysis may lead to fermentation or aerobic respiration
c) Each cystosolic NADH shuttling its electron to Ubiquinone will end up producing 2 molecules of ATP.
d) Each pyruvate molecule is converted to Acetyl CoA before entering the Kreb's cycle.

So here is what I know regarding this stuff. ​

a) The total amount of ATP produced is 36 ATP, right? Isnt there 34 from Oxidative Phosphorylation and 2 from Glycolysis for a total of 36? What is substrate level phosphorylation? How come it doesnt occur in the Electron Transport chain?

b) How does Glycolysis lead to Fermentation? doesnt fermentation have something to do with wine, making alcohol? Is fermentation, glucose ---> alcohol? Glycolysis is anaerobic, so how does it lead to an aerobic reaction?

c) I know that NADH =2 and FADH2 = 3 in glycolysis, but it doesnt specify whether this is for glycolysis or Oxidative Phos. or the transport chain or Krebs. Isnt it something like this?

for Krebs Cycle, Oxidative Phosphorylation, Calvin Cyle and the Electron Transport Chain, there is 2 ATP for FADH2 and 3 ATP for NADH? And Glycolysis is backwards?

d) Each pyruvate is turned to Acetyl CoA before entering the Kreb's cycle, please explain this. All I know is that Glycolysis produces pyruvate and Krebs produces Acetyl CoA(isnt this the final product of Krebs)?

please correct me on these things and explain them to me in children's terms so I can better understand them, thanks

 

[jdoc04]

So there is this question in DAT achiever that says that all of these are true:

a) Substrate level phosphorylation occurs in glycolysis and the Kreb's cycle.
b) Glycolysis may lead to fermentation or aerobic respiration
c) Each cystosolic NADH shuttling its electron to Ubiquinone will end up producing 2 molecules of ATP.
d) Each pyruvate molecule is converted to Acetyl CoA before entering the Kreb's cycle.

So here is what I know regarding this stuff. ​

a) The total amount of ATP produced is 36 ATP, right? Isnt there 34 from Oxidative Phosphorylation and 2 from Glycolysis for a total of 36? What is substrate level phosphorylation? How come it doesnt occur in the Electron Transport chain?

b) How does Glycolysis lead to Fermentation? doesnt fermentation have something to do with wine, making alcohol? Is fermentation, glucose ---> alcohol? Glycolysis is anaerobic, so how does it lead to an aerobic reaction?

c) I know that NADH =2 and FADH2 = 3 in glycolysis, but it doesnt specify whether this is for glycolysis or Oxidative Phos. or the transport chain or Krebs. Isnt it something like this?

for Krebs Cycle, Oxidative Phosphorylation, Calvin Cyle and the Electron Transport Chain, there is 2 ATP for FADH2 and 3 ATP for NADH? And Glycolysis is backwards?

d) Each pyruvate is turned to Acetyl CoA before entering the Kreb's cycle, please explain this. All I know is that Glycolysis produces pyruvate and Krebs produces Acetyl CoA(isnt this the final product of Krebs)?

please correct me on these things and explain them to me in children's terms so I can better understand them, thanks

They are a bit tricky but indeed true:

Substrate Level Phos--> is creating ATP from a GDP substrate which occurs in both glycolysis and krebs. Google Glycolysis and Krebs look for the flow charts that show the GDP-->ATP

Glycolysis --> 2 Pyruvates TWO FATES depending on conditions....Either enter krebs (aerobic) or fermentation (anaerobic)

You are totally right about NADH = 2 ATP via glycolysis....READ the answer choice carefully it tells you in a round about way. hint.........cytosol

Pyruvate can not enter the Mito therefore it has to be converted into acetyl coA in order to enter the Krebs.

It sounded like you know your stuff. You need to just pay more attention to the question and answers. Also be confident in your knowledge.

I hope this helps. If not PM me and I'll try to explain it a little better.

GOOD LUCK!!!!!!!!!

 

[BenignDMD]

Substrate level phosphorylation refers to production of ATP from GDP which is simultaneous with the oxidation of glucose to yield 6 CO2 molecules. Glycolysis is anaerobic and occurs in the cytoplasm. Glucose is converted into 2 pyruvate molecules. This produces a total of 4 ATP but only nets 2 because you have to spend 2 ATP to get your pyruvate molecules. Glycolysis also yields 2 NADH molecules.

In the absence of Oxygen, fermentation follows glycolysis in order to regenerate the NAD+ molecules needed for the next round of glycolysis. This also produces lactic acid in muscle cells and ethanol in yeast.

In the presence of Oxygen, pyruvate decarboxylaiton follows glycolysis. This produces to acetyal CoA molecules from the 2 pyruvate molecules of glycolysis. 2 CO2 and 2 NADH are also produced. This occurs in the mitochondrial matrix and uses 2 ATP to transport the 2 NADH molecules of glycolysis formt he cytoplasm to the matrix. The citric acid cycle produces the remaing 4 CO2 molecules and 6 NADH and 2 FADH2 molecules and also 2 ATP. Glucose has now been fully oxidized into 6 CO2 molecules and therefore substrate level phosphorylation is complete.

The NADH molecules and FADH2 molecules (total of 10 and 2 respectively) now dump their electrons for oxidative phosphorylation. You get 3ATP/NADH and 2ATP/FADH2. This is a total of 34.

So we have 34 from OxPhos, and 2 ATP from citric acid cycle for a total of 36 ATP.

The NADH from glycolysis only yield 2 ATP because of the "cover charge" of 1 ATP each that they must spend to enter the mitochondria.