QUESTION 1 The first step of glycolysis (some call it the inductive step, involv

Question

QUESTION 1

The first step of glycolysis (some call it the inductive step, involves the enzymatic addition of ________ phosphate(s) to glucose.

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QUESTION 2

For each glucose that begins glycolysis, how many ATP are SPENT to drive the process (phosphorylate substrates in glycolysis)?

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QUESTION 3

NAD+ coenzymes are reduced to NADH during glycolysis and in other steps of cell respiration. In a sense the reduction of these coenzymes is more important than the production of ATP in glycolysis because the electrons carried to the electron transport chain by these coenzymes drives the production of vastly more ATP.

Keep in mind that glucose is split into a pair of 3-carbon -long intermediates (3-phosphoglyceraldehyde). In the presence of oxygen, for each glucose that began glycolysis, how many NAD+ are reduced to NADH during glycolysis?

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QUESTION 4

Keeping in mind the splitting of glucose into a pair of smaller intermediates in step 4 of glycolysis, what is the NET yield of ATP from glycolysis, directly? Rem, I am asking for theoretical maximum, net. If it helps, give me the number produced in the absence of oxygen; i.e., during anaerobic glycolysis.

Rem: Net = total produced - amount spent.

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QUESTION 5

In the presence of oxygen, the pyruvate from the intermediate step is convered to acetyl CoA and CO2. In the process (for each pyruvate) an NAD+ is reduced to NADH. Thus for each glucose that began glycolysis, ___ more NAD+ are reduced to NADH as a byproduct of this intermediate reaction.

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QUESTION 6

The Krebs cycle is a series of enzymatically-catalyzed reactions that ultimately eliminates the remaining carbons from glycolysis as CO2. In the process, 2 ATP are indirectly produced (per glucose; 1 per acetyl-CoA). More importantly, for each Acety-CoA that enters this cycle of reactions,  NAD+ are reduced to NADH. Thus, for each glucose that began glycolysis,  NAD+ are reduced to NADH during the Krebs cycle.

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QUESTION 7

As in the prior question, the Krebs cycle is a series of enzymatically-catalyzed reactions that ultimately eliminates the remaining carbons from glycolysis as CO2.

In addition to NADH, for each Acety-CoA that enters this cycle of reactions,  FADH+ are reduced to FADH2. True, the electrons carried by FADH2 enter electron transport at a lower energy level and thus only lead to (theoretical max) the production of 2 ATP for each FADH2. Still, they need to be counted. Thus, for each glucose that began glycolysis,  FADH+ are reduced to FADH2 during the Krebs cycle.

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QUESTION 8

Tally up the yields of our metabolism of glucose. Per glucose, glycolysis netted  ATP and the Krebs cycle (indirectly) yielded  for a total of . To this point that is it for ATP. However, adding together the yields form glycolysis, the intermediate step and the Krebs cycle, one notes that metabolism of each glucose provided for the reduction of  NAD+ to NADH and the reduction of  FADH+ to FADH2.

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QUESTION 9

Pairs of electrons from NADH are transferred to cytochromes embedded in the inner mitochondrial wall and passed form protein to protein. At three points in this electron transport chain those pairs of electrons drive pumping of protons. Each pumping event point creating a proton gradient capable of driving the production of one ATP via the enzyme ATP synthase. Thus, each NADH may drive the production of up to three ATP via the energy that is transfers to a proton gradient. At the end of the chain, the electrons are transfered to oxygen and hydrogen, thereby making water.

In theory, the total NADH produced by the metabolism of a glucose molecule (Glycolysis, Intermediate, Krebs combined), could fuel the production of up to [a] ATP

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QUESTION 10

Pairs of electrons from FADH2 are transferred to cytochromes embedded in the inner mitochondrial wall at a lower energy level and later in the chain than those contributed by NADH. Only at two points in the electron transport chain do those pairs of electrons drive pumping of protons. Thus, each FADH2 may drive the production of up to two ATP via the energy that is transfers to the proton gradient. Agasin at the end of the chain, the electrons are transfered to oxygen and hydrogen, thereby making water, thus the term oxidative phosphorylation.

In theory, the total FADH2 produced by the metabolism of a glucose molecule (Glycolysis, Intermediate, Krebs combined), could fuel the production of up to [a] ATP

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QUESTION 11

All in all, in the presence of oxygen and taking into account the net ATP produced during glycolysis, Krebs (indirect) and ETS, the metabolism of one glucose may yield (net ) up to [a] ATP. In reality some energy is lost due to transport processes and proton leak so most textbooks express a lower number to account for these factors.

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QUESTION 12

Mammalian cells have a limited capacity for anaerobic metabolism, typically. However, when oxygen is absent or low mammalian cells will utilize anaerobic glycolysis yielding a pair of lactate molecules and [a] ATP for each glucose. Not exactly the same ATP production seen when oxygen is available.

Explanation / Answer

Question 1.

Answer: It involves the addition of Phosphate from adenosine tri phosphate

Question 2.

Answer: In a glycolysis reaction total ATP spent is 2 ATP, one during the first step to convert glucose to glucose-6-phosphate and the other during 3 step to convert fructose-6-phosphate to fructose-1,6-bisphosphate.

Question 3.

Answer: during glycolysis glyceraldehyde-3-phosphate is converted into 1,3-bisphosphoglycerate during which two NAD+ molecules are converted into 2NADH .

Question 4.

Answer: Net= total produced - Amount spent

Total produced = 4 ATP ( 2 ATP during the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and 2 ATP during conversion of Phosphoenolpyruvate to Pyruvate )

Amount spent= 2 ATP ( one during conversion of glucose to glucose-6-phosphate and another during conversion of Fructose-6-phosphate to Fructose-1,6-bisphosphate )

NET= 4ATP-2ATP = 2ATP.

The number of ATP produced during anaerobic condition is also 2ATP Because the glycolysis process is independent of molecular oxygen.

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