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The effect of temperature on the survival of yeast cells

Debate and discussion of any biological questions not pertaining to a particular topic.

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Re: biology plan

Postby Ulbrid » Tue May 01, 2007 4:36 pm

wannabeaditz wrote:are you sure its the other way around
in my preliminary work the meth blue turned colourless when the yeast died


I'm sure, and so are a lot of the sources on the internet.

Wikipedia:
The blue indicator turns colourless in the presence of active enzymes, thus indicating living cells.
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Postby cherry_blossom » Tue May 01, 2007 4:47 pm

In the explanation I am just writing about how the enzyme works and how it affects the reaction, do i need to write about how it is used in the brewing industry? Also i have written about how temperature affects enzymes. Is this right? or is it unnecessary?
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Postby monkee_boy » Tue May 01, 2007 6:01 pm

do you even need the sucrose or glucose at all? I can't see that it serves any purpose. if you put it in from the start the yeast might ferment (?) but if you put it in just before you measure the percentage of live yeasts then it's in there too short a time to do anything...
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How do you separate yeast and methylene blue?

Postby stargirlamy » Tue May 01, 2007 6:33 pm

Before putting my solutions in the colorimeter i want to separate the yeast from the methylene blue because the yeast cells can scatter the light. I have a number of quesitons which i would be soooo grateful if someone helped me out on!
firstly; how can i separate the yeast cells from the methylene? Filter paper?
and how much yeast/glucose should i use in my test tubes? Does it matter?
Finally, in terms of preliminary work would experimenting with methods of separation count? or finding out the light absorbed in a solution where the enzymes are (a) active (b) denatured. as a form of control
This is really confusing me :S
Thanks
Amy
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Postby Ulbrid » Tue May 01, 2007 6:58 pm

monkee_boy wrote:do you even need the sucrose or glucose at all? I can't see that it serves any purpose. if you put it in from the start the yeast might ferment (?) but if you put it in just before you measure the percentage of live yeasts then it's in there too short a time to do anything...


The glucose/sucrose solution provide the enzymes within yeast cells with energy in order to carry out metabolic reactions. Therefore, in order for the indicator (methylene blue) to detect enzyme activity a sugar solution is needed; it's better to add it before heating, that's what i think anyway.
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Re: How do you separate yeast and methylene blue?

Postby Ulbrid » Tue May 01, 2007 7:01 pm

stargirlamy wrote:Before putting my solutions in the colorimeter i want to separate the yeast from the methylene blue because the yeast cells can scatter the light. I have a number of quesitons which i would be soooo grateful if someone helped me out on!
firstly; how can i separate the yeast cells from the methylene? Filter paper?
and how much yeast/glucose should i use in my test tubes? Does it matter?
Finally, in terms of preliminary work would experimenting with methods of separation count? or finding out the light absorbed in a solution where the enzymes are (a) active (b) denatured. as a form of control
This is really confusing me :S
Thanks
Amy


You're really over-complicating things. First of all, it's probably better not to use a colorimeter in the first place because the yeast solution, unless heavily diluted, is too cloudy for any light to pass through. Secondly, i think it'd be really difficult to seperate the yeast suspension from the methylene blue. Besides, i doubt this would even work anyway because the yeast cells absorb the indicator solution which either stays blue or turns colourless so the yeast needs to stay!

You need a plentiful supply of sugar solution so the yeast cells aren't starved or in competition with one another. In mine i've used one part yeast and 2 parts glucose, but i have no idea if this is correct or not.
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Postby stargirlamy » Tue May 01, 2007 7:05 pm

ok thanks for the advice, i wont separate the solution. Would diluting the yeast work in the colorimeter then? if so how much would it need to be diluted? Im finding it quite difficult.
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Postby mith » Tue May 01, 2007 7:07 pm

Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
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