Thought provoking bio Q

[Ruthless]

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Take each step of Cell resp (glycolysis, pyru decarb, krebs, ETC) and photosynthesis (cyc, nocyc, calvin) and label then as oxidative or reductive and why? Might be more difficult then u think.

 

[r8 dds]

Take each step of Cell resp (glycolysis, pyru decarb, krebs, ETC) and photosynthesis (cyc, nocyc, calvin) and label then as oxidative or reductive and why? Might be more difficult then u think.

Umm..I'll give it a shot.

glycolysis, pyru, dearb, krebs --> reductive
ETC --> oxidative

cyc - oxidative
noncyc - reductive
calvin - oxidative

Yes? No? 😕

 

[UCB05]

Take each step of Cell resp (glycolysis, pyru decarb, krebs, ETC) and photosynthesis (cyc, nocyc, calvin) and label then as oxidative or reductive and why? Might be more difficult then u think.

Glycolysis: nets NADH. glucose is oxidized to pyruvate
Pyruvate Decarb: nets NADH. pyruvate is oxidized ot AcetylCoA
Krebs: nets NADH. AcetylCoA is consumed, carbons are oxidized to CO2
ETC: NADH is consumed. Oxygen is reduced to H2O

Cyclic Photosynth: only ATP is produced, no net electron transfer
Noncyclic: nets NADPH, H20 is oxidized to O2
Calvin: NADPH is consumed, CO2 is reduced to simple sugars

I hope I got all that right 🙂

 

[Shinpe]

I don't think you can think of it quite that way. EVERYTIME there's an oxidation, there has to be a reduction happening also. That's why they're called redox reactions. You can't have oxidation or reduction reactions by themselves (a half-reaction never happens by itself, hence HALF-reaciton). So the question is which element is being oxidized/reduced? One way that works usually is that OXidation is addition of OXygen (or removal of hydrogen) while REduction is REmoval of oxygen (or addition of hydrogen).

Then in Glycolysis, NAD+ is being converted to NADH (Thus NAD+ is reduced). What's being oxidized? Glucose (C6H12O6) going to pyruvate (C3H3O3) is oxidation because if you look hydrogens are being removed per each Carbon (If you had just split glucose in two, you would get C3H6O3, so you're losing 6 hydrogens total). There's more reactions in glycolysis but that's the balanced conversion.

In pyruvate decarboxylation, you have NAD+ going to NADH (reduction) so the other half of the reaction (pyruvate going acetyl-CoA) must be oxidation.

In kreb's cycle, again you're getting more NADH from NAD+ (reduction) and pyruvate is going to CO2 (oxidation)

In ETC, all proton carriers (NADH, FADH) lose their hydrogens (oxidation) and O2 is receiving hydrogens to give water (reduction).

So I guess the question is which element you are talking about. The overal net is oxidation of glucose all the way to CO2 and recution of O2 to H2O.

Same logic would apply to photosynthesis.

 

[Ruthless]

I don't think you can think of it quite that way. EVERYTIME there's an oxidation, there has to be a reduction happening also. That's why they're called redox reactions. You can't have oxidation or reduction reactions by themselves (a half-reaction never happens by itself, hence HALF-reaciton). So the question is which element is being oxidized/reduced? One way that works usually is that OXidation is addition of OXygen (or removal of hydrogen) while REduction is REmoval of oxygen (or addition of hydrogen).

Then in Glycolysis, NAD+ is being converted to NADH (Thus NAD+ is reduced). What's being oxidized? Glucose (C6H12O6) going to pyruvate (C3H3O3) is oxidation because if you look hydrogens are being removed per each Carbon (If you had just split glucose in two, you would get C3H6O3, so you're losing 6 hydrogens total). There's more reactions in glycolysis but that's the balanced conversion.

In pyruvate decarboxylation, you have NAD+ going to NADH (reduction) so the other half of the reaction (pyruvate going acetyl-CoA) must be oxidation.

In kreb's cycle, again you're getting more NADH from NAD+ (reduction) and pyruvate is going to CO2 (oxidation)

In ETC, all proton carriers (NADH, FADH) lose their hydrogens (oxidation) and O2 is receiving hydrogens to give water (reduction).

So I guess the question is which element you are talking about. The overal net is oxidation of glucose all the way to CO2 and recution of O2 to H2O.

Same logic would apply to photosynthesis.

Now that is what I call a logical, well stated, simple to understand explanation. Bravo!

 

[Shinpe]

Now that is what I call a logical, well stated, simple to understand explanation. Bravo!

Hehe, Thanks.

 

[jay47]

I don't think you can think of it quite that way. EVERYTIME there's an oxidation, there has to be a reduction happening also. That's why they're called redox reactions. .

Bravo.. couldn't be said better.