Both of you are wrong. Aerobic respiration does produce more CO2 than anerobic respiration. Aerobic respiration breaks glucose or in this case sucrose into CO2 + H2O. Sucrose containing 12 carbon atoms has the ability to produce 12 CO2 molecules aerobicly vs 2 CO2 molecules anaerobicly. The lag is not caused by the aerobic growth of yeast. It is actually caused by a lack of pressure in the bottle. In order for your yeast reactor to pump CO2 out, it first has to build up pressure to push the CO2 into the water column. This means the pressure has to be greater than the water pressure at the CO2 outlet. It also has to push the air out of the cansiter which is why it takes a few hours before the bubbles start to "dissolve" after they first appear since air is less soluble than CO2.
A thought on CO2 production with yeast
- Thread starter McJosh13
- Start date
Hey, I'm not wrong. I said my "lag" was 30 minutes. I get bubbles in 30 minutes, that's it and that's all I said.
Roan
Roan
*********Aerobic respiration breaks glucose or in this case sucrose into CO2 + H2O. Sucrose containing 12 carbon atoms has the ability to produce 12 CO2 molecules aerobicly vs 2 CO2 molecules anaerobicly.
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I would just like to add that when fermenting, 1 sucrose yields 1 glucose and 1 fructose. That 1 fructose is transformed into glucose.
1 sucrose = 2 glucose.
With or without oxygen, Glucose becomes 2 molecules of 3 carbon sugar. What becomes of this sugar (what is it? something like glyceraldehyde-3-phosphate or something, doesn't matter for us though).
No oxygen? When living, organisms need a place to dump electrons. That fate falls on a 3-carbon sugar, resulting in a 2 carbon sugar and Co2. A 2 carbon sugar? Hmmmm, I know what that is!!! Alcohol. (gulp gulp gulp). This 2 carbon sugar just floats around, unless the Yeast-reactor owner decides to 'do something' with it, like distillation freezing to make Jack Cider. he he he.
Oxygen present? Oxygen is the electron dump, because when it is the electrons pass along an electron chain involving may different proteins. In nearly each step energy is harnessed in the form of ATP and reducing power, which is NADH and NADPH. Good stuff you have, really! In so doing, But in this case the elecrtrons don't go directly to the 3 carbon sugar, rather the net result is that the 3 carbon sugar becomes a *usable* 2 carbon sugar called acetic acid (but this acetic acid isn't in a loose form, it's attached to an enzmy.e Acetyl-CoA, if you care. (no, I don't either).
Those extra carbons are recycled into biomass, or recycled into that TCA cycle (some call it Krebs, some call it Citric Acid, some call it hot). Ha ha ha.
Byut the point is that when oxygen is present, the metabolism is set to Anabolism, which is just a neat way of saying the eating of food and processing of it is used to create enzymes, proteins, longer -chain sugars, and car parts.
Catabolism is the breaking down of stuff. Like when you starve yourself and break down fat for energy. This is what I need to do, I'm pushing 200 myself, and am only 5 foot 10, with not too much muscle.
When our yeast guys slave away for us with oxygen, nearly all that sugar ends up in biomolecules. Starve it of oxygen, and the sugar ends up as alcohol because the 3-carbon thingy I can't remember (that's it I'm looing it up right now.....no, my bookss are in the basement.... I think it's Phosphenolpyruvate, becomes the electron dump, yielding CO2 and ethanol.
I think when you add fresh oxygen to the mix, the yeast stop fermenting and use the sugar aerobically. They stlp making CO2 because they ultimate electron acceptor isn't PEP anymore.
By the way, I think it's great fun to make up these bottles. Don't ask me why, it just it. The fun of fermenting sugar is what got me into homebrewing, and I don't even like beer!!! but I give myproduct to family members and they drink it up. Never had exploding bottles, but that day may come.!
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I would just like to add that when fermenting, 1 sucrose yields 1 glucose and 1 fructose. That 1 fructose is transformed into glucose.
1 sucrose = 2 glucose.
With or without oxygen, Glucose becomes 2 molecules of 3 carbon sugar. What becomes of this sugar (what is it? something like glyceraldehyde-3-phosphate or something, doesn't matter for us though).
No oxygen? When living, organisms need a place to dump electrons. That fate falls on a 3-carbon sugar, resulting in a 2 carbon sugar and Co2. A 2 carbon sugar? Hmmmm, I know what that is!!! Alcohol. (gulp gulp gulp). This 2 carbon sugar just floats around, unless the Yeast-reactor owner decides to 'do something' with it, like distillation freezing to make Jack Cider. he he he.
Oxygen present? Oxygen is the electron dump, because when it is the electrons pass along an electron chain involving may different proteins. In nearly each step energy is harnessed in the form of ATP and reducing power, which is NADH and NADPH. Good stuff you have, really! In so doing, But in this case the elecrtrons don't go directly to the 3 carbon sugar, rather the net result is that the 3 carbon sugar becomes a *usable* 2 carbon sugar called acetic acid (but this acetic acid isn't in a loose form, it's attached to an enzmy.e Acetyl-CoA, if you care. (no, I don't either).
Those extra carbons are recycled into biomass, or recycled into that TCA cycle (some call it Krebs, some call it Citric Acid, some call it hot). Ha ha ha.
Byut the point is that when oxygen is present, the metabolism is set to Anabolism, which is just a neat way of saying the eating of food and processing of it is used to create enzymes, proteins, longer -chain sugars, and car parts.
Catabolism is the breaking down of stuff. Like when you starve yourself and break down fat for energy. This is what I need to do, I'm pushing 200 myself, and am only 5 foot 10, with not too much muscle.
When our yeast guys slave away for us with oxygen, nearly all that sugar ends up in biomolecules. Starve it of oxygen, and the sugar ends up as alcohol because the 3-carbon thingy I can't remember (that's it I'm looing it up right now.....no, my bookss are in the basement.... I think it's Phosphenolpyruvate, becomes the electron dump, yielding CO2 and ethanol.
I think when you add fresh oxygen to the mix, the yeast stop fermenting and use the sugar aerobically. They stlp making CO2 because they ultimate electron acceptor isn't PEP anymore.
By the way, I think it's great fun to make up these bottles. Don't ask me why, it just it. The fun of fermenting sugar is what got me into homebrewing, and I don't even like beer!!! but I give myproduct to family members and they drink it up. Never had exploding bottles, but that day may come.!
Once the glucose enters the cell it is converted to Glucose 6 Phosphate. This phosphorilated glucose gets broken down into Pyruvate (Pyruvic Acid) where it can either be sent to the Krebs (Citric Acid Cycle) or sent to some other anabolic process. It can also be converted to lactic acid in the case of humans in the absense of oxygen or in the case of yeast ethanol (CH3CH2OH).
Go look up the Kreps/Citric Acid Cycle. Once the glucose is broken down into Pyruvate, it goes into this cycle. I am not going to go into the details of the Krebs cycle but the pyruvate gets converted into Acetyl CoA and Citric Acid and it churns through the cycle releasing 6 CO2 molecules. If you look at the waste products of the Krebs cycle it is CO2 + H2O. Glycolosis + Krebs Cycle is a catabolic reaction. This yields ATP (Up to 36 of them) which can be used to power Anabolic Reactions. Using more glucose as a precusor molecule as well as fats, and amino acids. The organism unless it is Autotrophic does not convert CO2 into other stuff. That is just inefficient and a plain waste of energy.
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You sure know your stuff, are you a biology major?
Going back to the actual bottle of yeast and sugar, can you explain something to me? When a fresh batch is made up, I never get any CO2 from the bottle to my tank. it is only when the oxygen runs out and fermentation takes place that the pressure buiilds up and I see the bubbles coming out from my tube (the end in the tank).
But if I understnad you correctly there should be plentyof CO2 being made during aerobic respiration. Then why isn't my tubing bubbling? How come it only bubbles during fermentation, without oxygen.
?????
It would be great for us (cheap) CO2 adders if this biochemistry would work out.
Going back to the actual bottle of yeast and sugar, can you explain something to me? When a fresh batch is made up, I never get any CO2 from the bottle to my tank. it is only when the oxygen runs out and fermentation takes place that the pressure buiilds up and I see the bubbles coming out from my tube (the end in the tank).
But if I understnad you correctly there should be plentyof CO2 being made during aerobic respiration. Then why isn't my tubing bubbling? How come it only bubbles during fermentation, without oxygen.
?????
It would be great for us (cheap) CO2 adders if this biochemistry would work out.
A few interesting excerpts
http://www.phys.ksu.edu/gene/a1.html
" Normal yeast can grow either aerobically, in the presence of oxygen or anaerobically, in the absence of oxygen. Under aerobic growth conditions they can support growth by oxidizing simple carbon sources, such as ethanol, acetate or glycerol. If they have adequate oxygen, they will completely oxidize their carbon sources, usually sugars, to carbon dioxide and water. However, under anaerobic conditions, deprived of oxygen, yeast can convert sugars only to carbon dioxide and ethanol, recovering less of the energy."
Something else interesting, if you skim through make sure you read the bottom
http://www.cyberlearn.com/ebio/messages/1878.htm
"The process of anaerobic respiration produces less ATP than aerobic respiration. In anerobic respiration, only two ATP per glucose are produced versus 36-38 ATP per glucose in aerobic respiration. This means that in aerobic respiration, fewer reactants are used to manufacture a larger product. This is the underlying concept as to why yeast consumes more sugar anaerobically versus aerobically.
In order to produce 36 ATP, yeast only needs one molecule of glucose in aerobic respiration, while it needs 18 molecules of glucose to produce the same amount of ATP using aerobic respiration.
This is true because the bulk of ATP gets produced in the electron transport chain using ATP synthase which requires oxygen. Anaerobic respiration does not involve this step. Its net ATP is only 2; the two which were generated in the last five steps by substrate level phosphorylation in glycolysis from NAD+. Fermentation simply generates more NAD+ which is needed to keep glycolysis going. So in order to produce a sufficient amount of energy, yeast needs to use nine times more glucose under anaerobic conditions versus aerobic conditions.
Aerobic conditions would be the most energy efficient for yeast. Even though it might be able to produce as much energy using fermentation as it would use aerobic respiration, fermentation is not the most efficient way. Since yeast consumes sugar so fast without any oxygen around, the sugar source will be depleted quickly. Once the sugar is gone, the yeast will be unable to undergo glycolysis and will therefore stop functioning. Aerobic respiration on the other hand will keep yeast alive longer because they will not need as much sugar to produce a great amount of energy."
http://www.phys.ksu.edu/gene/a1.html
" Normal yeast can grow either aerobically, in the presence of oxygen or anaerobically, in the absence of oxygen. Under aerobic growth conditions they can support growth by oxidizing simple carbon sources, such as ethanol, acetate or glycerol. If they have adequate oxygen, they will completely oxidize their carbon sources, usually sugars, to carbon dioxide and water. However, under anaerobic conditions, deprived of oxygen, yeast can convert sugars only to carbon dioxide and ethanol, recovering less of the energy."
Something else interesting, if you skim through make sure you read the bottom
http://www.cyberlearn.com/ebio/messages/1878.htm
"The process of anaerobic respiration produces less ATP than aerobic respiration. In anerobic respiration, only two ATP per glucose are produced versus 36-38 ATP per glucose in aerobic respiration. This means that in aerobic respiration, fewer reactants are used to manufacture a larger product. This is the underlying concept as to why yeast consumes more sugar anaerobically versus aerobically.
In order to produce 36 ATP, yeast only needs one molecule of glucose in aerobic respiration, while it needs 18 molecules of glucose to produce the same amount of ATP using aerobic respiration.
This is true because the bulk of ATP gets produced in the electron transport chain using ATP synthase which requires oxygen. Anaerobic respiration does not involve this step. Its net ATP is only 2; the two which were generated in the last five steps by substrate level phosphorylation in glycolysis from NAD+. Fermentation simply generates more NAD+ which is needed to keep glycolysis going. So in order to produce a sufficient amount of energy, yeast needs to use nine times more glucose under anaerobic conditions versus aerobic conditions.
Aerobic conditions would be the most energy efficient for yeast. Even though it might be able to produce as much energy using fermentation as it would use aerobic respiration, fermentation is not the most efficient way. Since yeast consumes sugar so fast without any oxygen around, the sugar source will be depleted quickly. Once the sugar is gone, the yeast will be unable to undergo glycolysis and will therefore stop functioning. Aerobic respiration on the other hand will keep yeast alive longer because they will not need as much sugar to produce a great amount of energy."
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How many people have fallen asleep by now? 
So it would seem that in fermentation, all of the sugar is consumed and metabolized into CO2 and ethanol.
That is, 6 pounds of sugar will yield 2 pounds of CO2 and 4 pounds of alcohol. (1 pound going to each "carbon").
Aerobic respiration burns all the sugar into CO2 and water. Therefore, 6 pounds of sugar yields 6 pounds of CO2.
But that is assumeing that the number and size of yeast cells remain constant. You know what I mean? ALL the mass of sugar gets transformed into CO2 and Alcohol for fermentation, and ALL the mass of sugar gets transformed into CO2 for aerobic. Since all the mass is accounted for, the mass of the yeast must not change. If this is the case, we should get 3 times as much CO2 out of the yeast with oxygen than without oxygen (6 pounds vs. 2 pounds).
But there is a very big but. We are assumeing the amount of yeast doesn['t change. Amount of yeast cells times how big they are can be called biomass.
In fermentation, biomass is constant (within a few percent anyway). So chuck in 6 pounds of sugar and get out 2 pounds of CO2.
In aerobic respiration, we have a situation where the yeast grow and multiply. Take 1 yeast cell, let it grow and divide (and grow a big more), and you have 2 yeast cells of the same size. The extra mass of that second yeast cell must have come from somewhere, and the only source of that mass is the carbon from the sugar. So, we our CO2 estimate from aerobic respiration is very much reduced because so much sugar is being used to create biomass.
If we could force the yeast to eat sugar but NOT actually grow and divide than yes, aerobic respiration would be more efficient in producing CO2. The original poster is quite correct. But we have all forgotton that given oxygen, yeast WILL grow and multiply, and a bunch of that sugar goes into biomass production and not our CO2.
So it would seem that in fermentation, all of the sugar is consumed and metabolized into CO2 and ethanol.
That is, 6 pounds of sugar will yield 2 pounds of CO2 and 4 pounds of alcohol. (1 pound going to each "carbon").
Aerobic respiration burns all the sugar into CO2 and water. Therefore, 6 pounds of sugar yields 6 pounds of CO2.
But that is assumeing that the number and size of yeast cells remain constant. You know what I mean? ALL the mass of sugar gets transformed into CO2 and Alcohol for fermentation, and ALL the mass of sugar gets transformed into CO2 for aerobic. Since all the mass is accounted for, the mass of the yeast must not change. If this is the case, we should get 3 times as much CO2 out of the yeast with oxygen than without oxygen (6 pounds vs. 2 pounds).
But there is a very big but. We are assumeing the amount of yeast doesn['t change. Amount of yeast cells times how big they are can be called biomass.
In fermentation, biomass is constant (within a few percent anyway). So chuck in 6 pounds of sugar and get out 2 pounds of CO2.
In aerobic respiration, we have a situation where the yeast grow and multiply. Take 1 yeast cell, let it grow and divide (and grow a big more), and you have 2 yeast cells of the same size. The extra mass of that second yeast cell must have come from somewhere, and the only source of that mass is the carbon from the sugar. So, we our CO2 estimate from aerobic respiration is very much reduced because so much sugar is being used to create biomass.
If we could force the yeast to eat sugar but NOT actually grow and divide than yes, aerobic respiration would be more efficient in producing CO2. The original poster is quite correct. But we have all forgotton that given oxygen, yeast WILL grow and multiply, and a bunch of that sugar goes into biomass production and not our CO2.
Yeast cannot grow and multiply off of sugar alone. They need a whole bunch of other things such as proteins, lipids and others. That is why they sell yeast nutrient packets for people producing beer, wine, etc. Without these the yeast will die before long (like in our regular bottles) but their enzymes continue working for some time since they don't require energy to function (they release energy from the catalyzed reaction)
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I'm glad I am studying physics and not biology or chemistry so I can just ask you guys about that kind of stuff. Its odd though, no one ever asks me about solutions to the Schrodinger equation on this site....just kidding.
Personally I don't like the idea of hydrogen peroxide so near my fish. I'll stick with regular way.
Personally I don't like the idea of hydrogen peroxide so near my fish. I'll stick with regular way.
