Why is cell fermentation considered anaerobic?
Also, what is the purpose of fermentation in the cell? does it only happen in yeast?
4 Responses
signius
12 Feb 2010
OKIM
12 Feb 2010
The process does not need oxygen.
All organisms can carry out fermentation: bacteria, fungi, plants and animals. In human muscle, glucose is broken down to lactic acid during exercise.
Dub
12 Feb 2010
Fermentation is the generation of energy without the use of oxygen. The definition of anaerobic is being done without oxygen, as opposed to aerobic (with oxygen).
Fermentation is done so that the carrier molecules (like NAD+) oxidizing the molecules (ex. glucose) being broken down can be reformed so that fermentation can continue. Using glycolysis as an example, glucose is broken down into pyruvate and two NAD+ are reduced to NADH for glycolysis to occur. But we only have a limited amount of NAD+ so if we run out we can’t continue glycolysis and thus produce no enery. Fermentation allows us to reform the NAD+ by carrying out a reaction that produced lactic acid or CO2 (like yeast do) and oxidizes the NADH to NAD+ allowing glycolysis to continue.
mareeclara
12 Feb 2010
In humans ( and plants) there are 2 processes of respiration, aerobic and anaerobic…..with an (in front of a vowel or h) in science it means WITHOUT…so in this case its without oxygen….in animal cells you get carbon dioxide+ water (+ 36 ATP molecules of energy) in aerobic respritation.
If there is limited or no oxygen then the cell "switches"to anaerobic respiration, where only 2 ATP molecules of energy are produced ( but the key is ENERGY is produced and the cell can continue to function, even if it is for short periods of time)…..the other by-product in animal cells is lactic acid, but this when it builds up causes bodies to become fatigued and can cause cramps…its actually a poison and you need to stop and allow aerobic respiration to continue to break it down.
Now long story, but this sets the scene for plants/fungi which also have both aerobic and anaerobic respiration …now their aerobic respiration is the same as in aniamls in what it produces however in anaeorbic conditions they produce ETHANOl ( and not lactic acid). This is a handy by-product for us as we use it in fermentation ( converting plant material into alcohol ( enthanol)…….we mainly use yeast but I"m sure that bacteria and I know plants also convert things into ethanol in anerobic respiration…….so during fermnatation processes you need to get rid of oxygen, other wise you allow aerobic repsiration to continue ( which produces bubbles of CO2…not good for wine etc)…..
I am not sure of the actual "purpose"of producing ethnaol, but I do know it is a hormone in plants for ripening fruit and flowers…..I am not sure if there is a link for other things, but like in animals it could just be a by=product of the process with no purpose.
Fermentation doesn’t require oxygen.
The term anaerobic means no oxygen is involved ("an" = no, "aerobic" = oxygen).
So there.
Fermentation is used mainly to release energy from food. This is done in cells that do not have the machinery to undergo aerobic respiration (obligatory aerobes eg. certain strains of yeast) or in cells that can undergo both aerobic and anaerobic respiration but lack the oxygen supply for aerobic respiration (non-obligatory aerobes eg. nearly every single cell in your body). An example is glycolysis in muscles that produce lactic acid.
A side effect or usage of fermentation in yeast is to produce alcohol to make beer and wine and such, but I guess that’s more of Man’s harnessing of nature. =p