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7

The main reason why alcohols (isopropanol and ethanol mostly) can be used as disinfectants is that they denature (bacterial) proteins. This is also the reason why they work on such a broad spectrum of microorganisms (bacteria, fungi, viruses), but not on spores, as these are better protected. The higher the concentration of the alcohol is, the faster this ...


6

So this is a good question. 70% is optimal for most cell types, especially those with a cell wall like prokaryotes. Wikipedia is a little off here. The reason you add water is to make the solution hypotonic. The alcohol disrupts the hydrophobic forces holding the phospholipids of the membrane while dehydrating any peptidogylcan of the wall enough to ...


4

The crystal violet stain will be removed if the decolorizer is left on too long. I'm assuming that the crystal violet complexes that are retained in the gram positive bacteria's peptidoglycan layers end up being washed away (perhaps from overdehydrtation).


4

Well, it turns out the situation is more complex. I had assumed the answer was what rwst suggests or something to do with osmotic pressure. It seems that we don't really know that well. In a paper from 1991, Chi and Wu suggest the following possible mechanisms : Membrane fusion during the shedding of exovesicles might produce a transient decrease of the ...


3

Drosophila is seen as a highly alcohol tolerant species which is mainly dependent on the environment it lives in. So are flies, which are captured in the cellar of a wine yard more tolerant to alcohol than flies which are captured outside (see first reference). The environment in which the flies grow up and live does not influence the activity of the ...


2

First of all Alcohol and Acetaldehyde are both cytotoxic. Along in our development we learned to deal with both substances, which is shown by specific metabolism pathways to break them down (for example alcohol dehydrogenase, acetaldehyde dehydrogenase, Cytochrom P450 and so on). Alcohol and Acetaldehyde both have a negative effect on mitosis (which ...


2

Well, I was intrigued by this, and my intuitive response was that it would never be toxic at reasonable doses, but I was wrong. A quick Google search led me to this paper: Andresen, H. et al. (2009) Severe glycerol intoxication after Menière's disease diagnostic--case report and overview of kinetic data. Clin. Toxicol. 47: 312 - 6 Apparently in the ...


1

Ethanol, in less than 50% concentration, emulgates lipids and, through interference with hydrogen bonds, leads to conformational changes in proteins. Higher concentrations lead to denaturation of proteins and osmolysis of cells through small defects, so they finally burst, as ethanol forces a concentration equilibrium. This is why it's a good desinfection ...


1

There aren't many studies which associate between alcohol consumption and cancer to my knowledge. The association is more with metabolic diseases because the liver is affected. Alcohol is oxidised to acetaldehyde by alcohol dehydrogenase. Acetaldehyde may also, in turn affect the cells by DNA damage if it is not metabolized quickly to acetyl-CoA (perhaps in ...



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