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Jul. 1st, 2008 05:29 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
ocelotPosted for my own future reference and in case anyone is either more familiar with the subject than me and wants to provide feedback or wants to attempt to learn about aerobic cellular respiration from my attempts to make sense of it.
(This is not exhaustive. There's a bunch of niggly details that we're not responsible for knowing, and I'm not necessarily including those here.)
1. Glycolysis
2 phases. In phase 1, the preperatory/investment stage, 1 molecule glucose (C6H12O6) enters the process. Two phosphate groups are added to the glucose molecule, using 2 ATP (ATP = Adenosine Triphosphate, which provides energy to cells. Taking a phosphate group from it turns it into ADP, or Adenosine diphosphate). An enzyme cuts the glucose molecule in two, resulting in two 3 carbon chains, each with a phosphate group, 3 oxygen, and 6 hydrogen.
Summary:
Put in:
1 glucose
2 ATP
Product:
2 3-carbon chains (C3H6O12P1)
Heat
(The diagram in the book is unclear at this point. It shows an H disappearing each time a phosphate group is attached. I'm assuming that there is a hydrogen bond there, and the hydrogen is just assumed as part of the phosphate group.)
Phase 2, the energy-conserving/payoff stage. Do process twice, for each 3-carbon molecule. 3-carbon molecule is oxidized (hydrogen leaves) and NAD+ is reduced to NADH. Another phosphate group appears by magic (this part confused me during class. The teacher told me it was outside the scope of the class and not to think about it so hard. So... magic) and attaches. This newly attached phosphate group goes away again, hooking up with an ADP and making ATP. A random oxygen that seems to have appeared along with that phosphate group hooks up with 2 hydrogens, forming the insidious dihydrogen monoxide. The remaining phosphate group goes towards another ATP. The resulting molecule is Pyruvic Acid/Pyruvate/C3H4O3.
Summary:
Put In:
2 3C chains
2 Magic phosphate groups
2 Magic oxygen
Product (for each molecule):
2 ATP
1 NADH
1 H2O
1 Pyruvic Acid
Heat
Total Product (of the entire process so far):
2 ATP
2 NADH
2 H20
2 Pyruvic Acid
Heat
Decarboxylation (x2):
Pyruvic acid cannot enter the Krebs cycle directly - it has to be 2 carbon. Coenzyme A takes care of that nasty carbon problem, conveniently reducing NAD+ to NADH and releasing nasty greenhouse gasses (C02) in the process, resulting in the molecule Acetyl CoA (C2H3OCoA?)
In:
2 Pyruvic acid
Product:
1 NADH
1 C02
1 Acetyl CoA
Heat
Total Product:
2 ATP
4 NADH
2 H20
2 C02
2 Acetyl CoA
Heat
Krebs Cycle (x2):
Acetyl CoA hooks up with an escort molecule (oxaloacetic acid) that goes with it through the cycle and ends up unchanged. Coenzyme A leaves and goes back to the previous step. More yucky greenhouse gas is lost, and an H (NAD+ -> NADH). More yucky greenhouse gas is lost, and an H (NAD+ -> NADH). That repetition is intentional. ATP is produced, then FAD -> FADH2. NAD+ -> NADH.
At this point, the original glucose molecule is all broken up. NADH and FADH2 to electron transport chain.
In:
2 Acetyl CoA
Product:
1 ATP
3 NADH
1 FADH
2 CO2
Heat
Total Product:
4 ATP
10 NADH
2 FADH
2 H2O
6 CO2
Heat
Electron Transport Chain/chemiosmosis:
H+ from all those NADH enter the electron transport chain, which converts it to ATP. A series of 3 proteins pump the H+ across the mitochondrial membrane. Each pump results in one ATP. This establishes a proton gradient. Every pump the H+ passes through allows 2 H+ to enter the cell and convert ADP to ATP, so 1 H+ = 3 ATP (for NADH. FADH skips the first pump, so only 2 ATP result).
Oxygen is the final hydrogen attractor in the chain (hence the name "aerobic respiration"). 2 H+ + 1/2 O2 = H2O. Need 6 O2 since we need one for every 2 NADH or FADH.
In:
10 NADH
2 FADH
6 Oxygen (O2)
Product:
34 ATP (10x3 + 2x2)
Total Product:
38 ATP
2 H2O
6 CO2
Heat
And my calculations here agree with the book, so that is good.
Homework: How much ATP could be obtained from 1 molecule of glucose? From one molecule of butterfat containing one glycerol and three 12 carbon chains?
Glucose: See above.
Glycerol is a 3 carbon chain, and enters at the decarboxylation step. Since there is just one of these, it passes through the cycle only once. 1 NADH is produced in the decarboxylation. Krebs cycle produces 1 ATP, 3 NADH, 1 FADH. Electron transport chain results in (4 NADH x 3 = 12 ATP + 1 FADH x 2 = 2 ATP). ATP = 15.
The carbon chains are broken down into two carbon molecules, which enter directly into the Krebs cycle. (12 x 3)/2 = 18 molecules entering Krebs cycle. 18x1 = 18 ATP, 18 x 3 = 54 NADH, 18 x 1 = 18 FADH. Electron Transport Chain results in (54 NADH x 3 = 162 ATP, 18 x 2 = 36 ATP). ATP = 18 + 162 + 36 = 216 ATP.
Total ATP = 15 + 216 = 231
Um, if you happen to follow that and see a problem with my math, please point it out.
(This is not exhaustive. There's a bunch of niggly details that we're not responsible for knowing, and I'm not necessarily including those here.)
1. Glycolysis
2 phases. In phase 1, the preperatory/investment stage, 1 molecule glucose (C6H12O6) enters the process. Two phosphate groups are added to the glucose molecule, using 2 ATP (ATP = Adenosine Triphosphate, which provides energy to cells. Taking a phosphate group from it turns it into ADP, or Adenosine diphosphate). An enzyme cuts the glucose molecule in two, resulting in two 3 carbon chains, each with a phosphate group, 3 oxygen, and 6 hydrogen.
Summary:
Put in:
1 glucose
2 ATP
Product:
2 3-carbon chains (C3H6O12P1)
Heat
(The diagram in the book is unclear at this point. It shows an H disappearing each time a phosphate group is attached. I'm assuming that there is a hydrogen bond there, and the hydrogen is just assumed as part of the phosphate group.)
Phase 2, the energy-conserving/payoff stage. Do process twice, for each 3-carbon molecule. 3-carbon molecule is oxidized (hydrogen leaves) and NAD+ is reduced to NADH. Another phosphate group appears by magic (this part confused me during class. The teacher told me it was outside the scope of the class and not to think about it so hard. So... magic) and attaches. This newly attached phosphate group goes away again, hooking up with an ADP and making ATP. A random oxygen that seems to have appeared along with that phosphate group hooks up with 2 hydrogens, forming the insidious dihydrogen monoxide. The remaining phosphate group goes towards another ATP. The resulting molecule is Pyruvic Acid/Pyruvate/C3H4O3.
Summary:
Put In:
2 3C chains
2 Magic phosphate groups
2 Magic oxygen
Product (for each molecule):
2 ATP
1 NADH
1 H2O
1 Pyruvic Acid
Heat
Total Product (of the entire process so far):
2 ATP
2 NADH
2 H20
2 Pyruvic Acid
Heat
Decarboxylation (x2):
Pyruvic acid cannot enter the Krebs cycle directly - it has to be 2 carbon. Coenzyme A takes care of that nasty carbon problem, conveniently reducing NAD+ to NADH and releasing nasty greenhouse gasses (C02) in the process, resulting in the molecule Acetyl CoA (C2H3OCoA?)
In:
2 Pyruvic acid
Product:
1 NADH
1 C02
1 Acetyl CoA
Heat
Total Product:
2 ATP
4 NADH
2 H20
2 C02
2 Acetyl CoA
Heat
Krebs Cycle (x2):
Acetyl CoA hooks up with an escort molecule (oxaloacetic acid) that goes with it through the cycle and ends up unchanged. Coenzyme A leaves and goes back to the previous step. More yucky greenhouse gas is lost, and an H (NAD+ -> NADH). More yucky greenhouse gas is lost, and an H (NAD+ -> NADH). That repetition is intentional. ATP is produced, then FAD -> FADH2. NAD+ -> NADH.
At this point, the original glucose molecule is all broken up. NADH and FADH2 to electron transport chain.
In:
2 Acetyl CoA
Product:
1 ATP
3 NADH
1 FADH
2 CO2
Heat
Total Product:
4 ATP
10 NADH
2 FADH
2 H2O
6 CO2
Heat
Electron Transport Chain/chemiosmosis:
H+ from all those NADH enter the electron transport chain, which converts it to ATP. A series of 3 proteins pump the H+ across the mitochondrial membrane. Each pump results in one ATP. This establishes a proton gradient. Every pump the H+ passes through allows 2 H+ to enter the cell and convert ADP to ATP, so 1 H+ = 3 ATP (for NADH. FADH skips the first pump, so only 2 ATP result).
Oxygen is the final hydrogen attractor in the chain (hence the name "aerobic respiration"). 2 H+ + 1/2 O2 = H2O. Need 6 O2 since we need one for every 2 NADH or FADH.
In:
10 NADH
2 FADH
6 Oxygen (O2)
Product:
34 ATP (10x3 + 2x2)
Total Product:
38 ATP
2 H2O
6 CO2
Heat
And my calculations here agree with the book, so that is good.
Homework: How much ATP could be obtained from 1 molecule of glucose? From one molecule of butterfat containing one glycerol and three 12 carbon chains?
Glucose: See above.
Glycerol is a 3 carbon chain, and enters at the decarboxylation step. Since there is just one of these, it passes through the cycle only once. 1 NADH is produced in the decarboxylation. Krebs cycle produces 1 ATP, 3 NADH, 1 FADH. Electron transport chain results in (4 NADH x 3 = 12 ATP + 1 FADH x 2 = 2 ATP). ATP = 15.
The carbon chains are broken down into two carbon molecules, which enter directly into the Krebs cycle. (12 x 3)/2 = 18 molecules entering Krebs cycle. 18x1 = 18 ATP, 18 x 3 = 54 NADH, 18 x 1 = 18 FADH. Electron Transport Chain results in (54 NADH x 3 = 162 ATP, 18 x 2 = 36 ATP). ATP = 18 + 162 + 36 = 216 ATP.
Total ATP = 15 + 216 = 231
Um, if you happen to follow that and see a problem with my math, please point it out.
