I have the following lists:

Hot Water Effects on Human Cells:
When human cells are exposed to hot water:

   Denaturation of Proteins:
   The proteins within cells denature, 
   losing their normal three-dimensional structure.

   Cell Membrane Damage: 
   The cell membrane can be damaged by heat. 
   The lipids in the membrane become more fluid. 

   Increased Metabolic Activity: 
   Increase the metabolic activity of cells. 
   Can lead to cellular stress and even cell death.


Cold Water Effects on Human Cells:

    Reduced Metabolic Activity:
    Slow down the metabolic activity of cells. 
    This is one reason why hypothermia can be life-threatening.

    Cell Membrane Changes: 
    Cell membrane to become less fluid,
    potentially affecting its permeability and functionality.

    Ice Formation: 
    Extreme cold can cause ice crystals to form
    within and around the cells.

But I really want to see these up close under a microscope.

The temperatures don't have to be extreme. Just like mildly cold ice water vs. a warm shower. When the cold water hits a cell do you see it like bounce off? When the warm water hits a cell do you see it enter the cell?


1 Answer 1


You can't see these changes easily under a microscope. It is a challenge to add heat or cold to cells on a microscope in a manner that you might see, unless you have the right equipment.

You might see protein denaturation - it's like an egg cooking, but because the cells are so small, it happens very fast and you aren't left with a residue, the cells detach before this happens or just disintegrate. For this to happen you need to be heating above about 55 - 65 C (131 - 149 F) for observable denaturation - this is about the same temp as egg white denatures (IIRC 61 C/141 F), but some proteins denature much earlier. Part of the reason it is so difficult to see is the range of temperatures it happens over, so the process is spread out.

Membrane fluidity is not something you will see at all unless you are making specific measurements of it - the cells just don't move enough for you to notice the difference between warm and cold. Water doesn't "bounce off" or enter cells because of membrane fluidity - it enters through protein channels called aquaporins - you can't see these either, far far far too small for light microscopy.

Adding water to the cells (note - cells don't like water in general, mammalian cells need isoosmotic conditions with some salt to keep them happy or they undergo osmotic stress and pop, which you might see, but it isn't dramatic at all). As they are already in a liquid - Have you ever added hot water to cold - how much difference do you see? How would you know when the cold/hot water reached the cells?


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