Anaerobic Respiration in Yeast SAC

[ifelthope]

Hi, has anyone done an anaerobic respiration SAC for Biology Unit 3? I haven't seen anyone discussing this, only the photosynthesis one. If you have, could you please tell me what knowledge was required and what experiment you did. Mine is first week back at school and so I want to be prepared for it since I have all holidays, however she hasn't mentioned what things are going to be tested. Any help would be greatly appreciated.

[Yacoubb]

I haven't done it but I suppose you'll be investigating the rate of anaerobic respiration (fermentation in yeast) at different pH levels, and investigating which has the greatest rate of aerobic respiration. Not 100% sure but this is the SAC I did in 1+2 Bio. Study anaerobic respiration, what happens in glycolysis, experimental design & you should be fine!

[AbominableMowman]

I've done it and mine was on the fermentation of yeast at different glucose concentrations (apparently it's a common one). What we basically did was prepare different concentrations of glucose with yeast in test tubes, and then record the amount of bubbles that it released per second, which was the carbon dioxide released from the anaerobic reaction (rate of reaction). Just know about how anaerobic reaction occurs in yeast, and also about which factors would affect the rate of reaction and how enzymes in yeast are affected by different factors.

[hungover]

it was super fun. if you can go, go with the bearded guy, he is the best instructor there.

It was basically researching cancer cells and how we could stop their growths. i would give you the GTAC booklet but my teacher has that.
you look at how glucose affects their growth.
you look at the warberg effect.
you look at upregulated and downregulated genes.
That was it.

[Yacoubb]

Why is it that after glycolysis in anaerobic respiration, the pyruvate is converted to lactic acid in animals, whereas in plants/yeast, the pyruvate is converted to ethanol (alcohol) + CO₂? Always knew how it happened, but never why?

[Snorlax]

Why is it that after glycolysis in anaerobic respiration, the pyruvate is converted to lactic acid in animals, whereas in plants/yeast, the pyruvate is converted to ethanol (alcohol) + CO₂? Always knew how it happened, but never why?

Because plants don't have muscle tissue?

[Yacoubb]

Because plants don't have muscle tissue?

Yeah its particular enzymes found in muscle tissue that enables the conversion of pyruvic acid to lactic acid. In plants that lack muscles + the enzymes that convert it to lactic acid, the pyruvate molecules are converted to CH₃CH₂OH (ethanol) + CO₂

[violanoob8]

I am pretty sure that it is because, though it would be far more useful for plants to use lactic acid fermentation, (even it if wastes energy making the enzymes to convert it to lactic acid and back), lactic acid would like poison to plants as it has a pH of around 3.86, which is really acidic and that would throw so many things out of balance, so instead it makes alcohol which has an almost neutral pH.

[Yacoubb]

I am pretty sure that it is because, though it would be far more useful for plants to use lactic acid fermentation, (even it if wastes energy making the enzymes to convert it to lactic acid and back), lactic acid would like poison to plants as it has a pH of around 3.86, which is really acidic and that would throw so many things out of balance, so instead it makes alcohol which has an almost neutral pH.

I think one reason why animals do not sustain anaerobic cellular respiration over a prolonged period of time is because lactic acid accumulation lowers blood pH, and so the tissue is bathed in an almost acidic blood which consequently results in muscle fatigue. Plants cannot have too much ethanol accumulation because it is toxic to their cells and as you said, too acidic.

[violanoob8]

Actually, it is now thought that muscle fatigue and pain is a result of the increasing levels of potassium ions and not the lactic acid. Lactic acid is thought to actually help muscle performance.

Ethanol is almost neutral so it is not "too acidic" to the plant, and some plants have even developed a huge tolerance for ethanol. I think that it relates more to the lack of energy it produces, as though fermentation can sustain a small unicellular organism (or some fungi but that is another story) , I don't think it can sustain a multi-cellular organism as large as a plant for long at all.

[Yacoubb]

Actually, it is now thought that muscle fatigue and pain is a result of the increasing levels of potassium ions and not the lactic acid. Lactic acid is thought to actually help muscle performance.

Ethanol is almost neutral so it is not "too acidic" to the plant, and some plants have even developed a huge tolerance for ethanol. I think that it relates more to the lack of energy it produces, as though fermentation can sustain a small unicellular organism (or some fungi but that is another story) , I don't think it can sustain a multi-cellular organism as large as a plant for long at all.

Well that just demonstrates how science is constantly making these new discoveries. I'd probably say that the inefficiency of having only 2 ATP molecules/glucose molecule converted from glucose is why it is sustained over a short period of time. I haven't actually started Photosynthesis/Cellular Respiration in class; however, I want to pull some strands of background info regarding this biochemistry so that I can solidify my understanding.

I would say that lactic acid to some degree does enhance muscle performance; however, I'd say that the accumulation of lactic acid in muscles is what results in mucle fatigue. Think about it; over that short period of strenous exercise, your muscle tissue cells respire anaerobically. However, when all this lactic acid accumulates, its the fatigue it causes. It can also somehow be related to increased K+ ions, however, it definitely has to do with the accumulation of lactic acid...

[Snorlax]

Actually, it is now thought that muscle fatigue and pain is a result of the increasing levels of potassium ions and not the lactic acid. Lactic acid is thought to actually help muscle performance.

Still just a theory