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6

Your sugar substrate was sucrose. Yeast cells metabolise this by secreting an enzyme, invertase, which splits the disaccharide into glucose and fructose both of which can be fermented by yeast to produce CO2. According to this site Equal Original (blue packaging)  is a zero calorie sweetener that contains aspartame and acesulfame potassium as its ...


5

There are some recipes available on the web, my answer is based on this webpage and this information: The process itself is rather easy and you can either use ready bought apple juice, homemade juice or apple cider (basically unfiltered apple juice). You will need some specially cultivated yeast, baker's yeast is generally not recommended since it might ...


4

Short answer (A) is a possible answer and is indeed cause for fatigue, as pyruvate is needed for the Krebs cycle to run. The krebs cycle is an essential step in the generation of ATP in aerobic organisms. (B) is incorrect because NADH is never transported into the mitochondria in any organism (it is a nonsense answer). Background NADH is not transported ...


3

Yes, it is possible to reuse yeast in both beer and wine fermentation - commercial brewers do it all the time for cost savings and batch reproducibility, and although I'm not as familiar with making wine, many sites including this one say it's perfectly fine, as long as the viability of the cells is high enough. The yeast aren't necessarily in ...


3

Suppose the cellular pool has $x$ATP before starting glycolysis. In the initial phosphorylation steps, we use up two ATP to get the total tally at $(x-2)$ATP. The following steps yields $4$ ATP which brings the final total to $(x+2)$ATP. Assuming the cell is performing fermentation, the two additional $NADH$ formed will not be contributing to any ATP gain. ...


3

Remember that glycolysis yields 2 NADH as well as 2 net ATP. This NADH can be used to a terminal electron acceptor to produce an end product with a net gain of ATP. End-products of fermentation can include lactate, acetate, butyrate, propionate and ethanol, all of which generate different amounts of additional ATP. The exact pathways involved vary ...


2

I think the reason as to why glucose concentration is faster in the aerobic case than the anaerobic one, is perfectly explained by Chris. To summarize:- The energy requirement of the organism in both the condition remains more or less constant. Since aerobic respiration generates more energy per glucose,(38ATP) it takes more time for the same ...


2

Almost certainly not. Species occupy different niches due to their differing growth rates and tolerances. Interspecies quorum sensing and the symbiotic relationship that implies do exist(see: lichen), but open-air inoculation is unlikely to produce them. Why would the Brettanomyces simply kill time waiting for 'their turn'? It's likely they don't grow as ...


2

generally, lactic acid bacteria (LAB) are the ones you should be looking at for milk-based fermentation products. although sometimes species like bifidobacterium are added, which is of a completely different phylum. also, for cheese production, or the Dutch variety I am familiar with anyway, you would need fungi as well. the lactobacillales order is not ...


2

A "starter culture" is just a culture of preferred organisms. They probably differ little from local wild organisms. For example, a mixture of flour and water left to stand will (with luck) be colonized by yeast in the air that result in a serviceable yeast culture. Control of this process entails nothing more than observation over time. The environment and ...


2

I think only b.) is true. a. I cannot find evidence that maltose is toxic to yeasts (and I would hardly believe it, because it is a glucose dimer), however I found evidence, that yeasts might need the presence of oxygen to process maltose. 1977 - The Requirement of Oxygen for the Utilization of Maltose, Cellobiose and D-Galactose by Certain Anaerobically ...


1

This is an interesting question (I really mean this — see below), for which a straight answer is remarkably difficult to find on the web. When I googled for it I got pages with statements that obligate anaerobic bacteria still had the electron transport chain (ETC) and ATP synthase as there were different electron acceptors other than oxygen. Yes, we know ...


1

When glucose and fructose are fermented separately, the uptake profiles indicate that both sugars are utilized at similar rates. However, when fermentations are conducted in media containing an equal concentration of glucose and fructose, glucose is utilized at approximately twice the rate of fructose. The preferential uptake of glucose also occurred when ...


1

You're right, the answer is b since the presence of oxygen would lead to aerobic respiration and not fermentation. If maltose was toxic, the yeast wouldn't grow. Proteins are required for growth, but the yeast is growing. Any temperature that is extreme enough to prevent fermentation would also prevent other cellular processes and the yeast wouldn't ...


1

The discussion you linked (here) shows that both researchers agree that 'garbage enzymes' are mostly acetic acid or vinegar, with a low pH(3-4). Fresh papayas contain papain, but roughly 2% of the enzyme self-digests per day in aqueous solution. Bromelain from pineapples is still active at acidic pH. Like most other proteases, it self-digests much more ...


1

Your graphs show two things: Starting at the same concentration (150mM/l) the metabolization of glucose is not linear under anaerobic conditions. The other observation is that under aerobic conditions the glucose is metabolized much slower. This is because under anaerobic conditions on 2 molecules of ATP are generated from the metabolization of one molecule ...


1

I don't have a definitive answer to this, but a little over a decade ago I was in an undergraduate lab that had a similar thing happen - a small amount of metabolism of a "control" group of bacteria fed artificial, sugar/calorie free sweeteners instead of sugar. Our running theories at the time were: Contamination. Always a problem in laboratory ...


1

from wikipedia: No-additive salts for canning and pickling In contrast to table salt, which often has iodide as well as anticaking ingredients, special canning and pickling salt is made for producing the brine to be used in pickling vegetables and other food-stuffs. This salt has no iodine added because the iodide can be oxidised by the ...


1

I've done experiments with yeast, and they can easily ferment glucose at the rate of 4g/L/d. Probably faster, if one were to optimize it. So your numbers don't seem crazy.



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