effect of temperature on the survival of yeast cells

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Jacob
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Post by Jacob » Wed Apr 25, 2007 8:58 am

I've tried to look at what temperature that most of the yeast cells are killed at. It's in the region of around 55 to 60 degrees C.

abcdef
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sucrose/glucose

Post by abcdef » Wed Apr 25, 2007 1:08 pm

hi

does anyone kno whether using sucrose or glucose makes a difference?

thanx

flyingbarbie
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Post by flyingbarbie » Wed Apr 25, 2007 6:48 pm

must we write about fermentation in the hypothesis?

and is the dependable variable the colour of the solution after methylene blue is added?

infam0us
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Post by infam0us » Wed Apr 25, 2007 7:49 pm

Wagwan all you mad heads.

I too am conducting this investigation, and after some preliminary testing, the colour of the yeast + methylene solution turned from blue to colourless after heating, at quite high temperatures, e.g. 60-70 degress.

But I thought the indicator was supposed to turn colourless where there was enzyme activity? This means either:

- the yeast has a really high optimum temperature

or

- the methylene blue indicator turns colourless where there is NO enzyme activity, but I doubt that is the case.

Can anyone explain please?

flyingbarbie
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Post by flyingbarbie » Wed Apr 25, 2007 7:56 pm

The blue indicator turns colourless in the presence of active enzymes, thus indicating living cells

funky pisces
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reply to star12

Post by funky pisces » Wed Apr 25, 2007 8:49 pm

hey star12
u stated that u used a temp range of 40 - 70 and they all turned clear ryt?wel they turned clear because the yeast cells were resprirng which ment that they were still alive...but i thnik you myt have dun sumting rong as u wud expect the cells to be ded by about 60 so ur solotuion should have remained blue at this temp?
funky pisces xxxx

Jacob
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Post by Jacob » Thu Apr 26, 2007 10:23 am

Methylene blue is one indicator for showing living cells is there another one and does methylene blue turn colourless in the presence of oxygen or active enzymes?

leaping badger
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Post by leaping badger » Thu Apr 26, 2007 3:44 pm

anyone think of any crazy safety precautions that might be needed?

Steen
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Post by Steen » Thu Apr 26, 2007 3:51 pm

Spoke to the technicians at school and they said not really....just goggles tho it depends on the equpment you are using. And an apron may be advisable, given that the methylene blue is a dye

CrimsonFalcon
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Post by CrimsonFalcon » Thu Apr 26, 2007 4:08 pm

also in the safety, if your using test tubes perhaps you may want to say how you are going to be careful not to break them? ... maybe even have cleaning up material with you too incase that does happen so that you are at least prepared.

leaping badger
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Post by leaping badger » Thu Apr 26, 2007 4:11 pm

[quote=]also in the safety, if your using test tubes perhaps you may want to say how you are going to be careful not to break them? ... maybe even have cleaning up material with you too incase that does happen so that you are at least prepared.[/quote]

good idea

[quote=]Spoke to the technicians at school and they said not really....just goggles tho it depends on the equpment you are using. And an apron may be advisable, given that the methylene blue is a dye[/quote]

:shock: i didn't realise they could even talk

CrimsonFalcon
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Theory

Post by CrimsonFalcon » Thu Apr 26, 2007 4:13 pm

im struggling a little on writing the theory... what should i be putting into it? i can gues roughly but im still not so sure. anyone that can help here?

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