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effect of temperature on the survival of yeast cells

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Postby david23 » Mon May 07, 2007 4:59 pm

Tifa, it's funny how there is this other biology help site that has the same questions running, but they are charging $20/hour for their work. Maybe these people should adopt this policy
Last edited by david23 on Mon May 07, 2007 6:37 pm, edited 1 time in total.
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Postby playdoh » Mon May 07, 2007 6:27 pm

Grr!!

I had this plan done perfectly, but now I've got to change it, cos my teacher told me that we're not looking for the lowest temperature above the optimum, but the lowest temperature, as in 4 degrees or something. :?

And that's really confused me, cos I thought that the yeast was just inactive at really low temperatures? :?
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Postby blcr11 » Mon May 07, 2007 7:18 pm

Far be it from me to contradict your teacher, but that doesn't make a lot of sense to me. You can deep freeze yeast (as in -80 C) and they can survive. What is the point of trying to find a "cold" temperature minimum? If you go low enough and sloppily enough you can kill cells by ice formation, I guess, but how are you going to find the "highest low temperature" using ordinary college laboratory equipment? I would ask for a second opinion.
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Postby daalchawal » Wed May 09, 2007 3:29 pm

basically heres wot i think youre meant to do.
put the yeast wiv glucose/sucrose into test tube
add methylene blue
it will eventually go clear becuase yeast is definitely alive at room temperature.
then heat to wotever and retest it if it stays blue yeast is dead and enzymes denatured if not its alive and increase temperature before retesting.
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Postby nano » Sat May 12, 2007 10:49 am

dose any one know how much water needs to be added to the solutions?
and good luck for next week all

x
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Postby biology1133 » Sat May 12, 2007 8:38 pm

all of you are talking about this and saying you nedd to find the highest temperature it clearly says in bold as well 'You are required to plan an investigation to find the lowest temperature that kills all the yeast cells in a suspension of either dried or fresh yeast cells.' Just thought i would let you know so you don't get it all wrong!!
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Postby LMAOS » Sun May 13, 2007 2:43 pm

i need some variables that need to be kept constant
so far i have 3 out of five
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Postby <Singing Mice> » Sun May 13, 2007 2:50 pm

Foo wrote:
First of all, would that be 'foo' for the legendary band that is the foo fighters? if yes, there my fave band so woohoo!
Um, microscope or colorimeter? Well the colorimeter will tell you the exact amount of light that is being transmitted through the solution (100% would be a perfectly clear solution so the cells would all be alive, 40%ish would mean they were all dead [ive been told]) but if you have a good eye for colours a microscope could be ok, but a colorimeter is more accurate. Got any tips of your own? :D


hmm
one of those haemocytometer slides is what my teacher said to use and then calculate the percentage that are dead or alive (dead would be blue, alive would be clear). Would a colorimeter work because the liquid would still have the yeast solution in and so would never be actually clear. or am i just having a blonde monent??

And also, I'm not named after the Foo Fighters, it's just what a handful of my friends call me. how odd. but i am also a fan of said band so yay!

xxx


Do you know what, i dont have a pissing clue! :roll: this is only a theory excercise anyway, we dont have to actually do it for the exam, so im not worrying about it. theres loads of different ways to get the results so im just gonna write about one of them. have you got any ideas what the practical will actually be on, or is it different for each school?
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Postby Tifa » Sun May 13, 2007 2:58 pm

I'm hoping that the practical will be on enzyme reactions and that the microsope work will be on a cross section of a leaf and you have to do a plan diagram of it.
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Postby <Singing Mice> » Sun May 13, 2007 3:03 pm

Tifa wrote:I'm hoping that the practical will be on enzyme reactions and that the microsope work will be on a cross section of a leaf and you have to do a plan diagram of it.


:shock: Yeah that would make sense actually cos weve been looking at sections of stems and leaves through the microscopes and having to label stuff like the epidermis, cortex, casparian strip, xylem etc etc boring boring boring.
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Postby LMAOS » Sun May 13, 2007 10:19 pm

The actual practical will be related to the planning task already set
yeast?
fermentation maybe?
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Postby <Singing Mice> » Mon May 14, 2007 8:43 pm

Does anyone know whether yeast enzymes are similar to body enzymes? i know that the body ones work best at 37 degrees, but is it the same for yeast.?Its for my predicted results, i fluffed the pre-lim good and proper lmao!
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