effect of temperature on the survival of yeast cells

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CrimsonFalcon
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Post by CrimsonFalcon » Thu Apr 26, 2007 9:06 pm

righty-ho thankies! that helped

CrimsonFalcon
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Post by CrimsonFalcon » Thu Apr 26, 2007 9:51 pm

Well, thats me done! good luck to those still doing it! ^_~ if you have any problems, seriously have a good look through this forum. all you need to know it here pretty much, and google some rubbish too ^_^ wikipedia sometimes is helpful too... meh. DO YAH BEST! and good luck. no worries if you can't do it - its a small % that you can make up by some extra correct ansewers in yah test! good luck! w^_~V

Steen
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Post by Steen » Thu Apr 26, 2007 9:57 pm

This is me done too. One word of advice....some of the stuff on here needs checking for verification but its been a great help for answers and throwing out suggestions and knowing there are other people in the same boat! Best of luck to anyone else still doing it. Don't stress out too much. Steen x

01addiv-llangirb
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Post by 01addiv-llangirb » Fri Apr 27, 2007 11:05 am

Well done to the both of you.

Hope you do well in the summer.

dee88
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yeast cells and temperature experiment

Post by dee88 » Sat Apr 28, 2007 11:42 am

i have a rough idea of what i would be doing in the experiment however have a few queries. i am going to be adding the methylene blue to 0.01% of yeast solution, not sure whether to add before heating in water bath or after same goes with the sucrose/glucose solution and which one would be better to use and how much of each would i require. we were supposed to carry out a preliminary experiment but the only thing i found out was the concentration of yeast im going to be using not how much of the dye or the sugar. if you are unsure please say.

Ulbrid
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Re: yeast cells and temperature experiment

Post by Ulbrid » Sat Apr 28, 2007 12:10 pm

dee88 wrote:i have a rough idea of what i would be doing in the experiment however have a few queries. i am going to be adding the methylene blue to 0.01% of yeast solution, not sure whether to add before heating in water bath or after same goes with the sucrose/glucose solution and which one would be better to use and how much of each would i require. we were supposed to carry out a preliminary experiment but the only thing i found out was the concentration of yeast im going to be using not how much of the dye or the sugar. if you are unsure please say.


Right. There's no point adding methylene blue until the end, so we'll leave this point for now. I'd mix the glucose/sucrose solution and yeast suspension together, then heat because... well because there's not really any valid reason to do otherwise and it's just easier. As for the amount of glucose/sucrose solution to use, in my plan i'm using a 2:1 ratio so there's double the amount of sucrose solution (in my case) compared with the yeast solution. Basically, you just need to make sure that there is an ample amount of sugar solution for all of the yeast because, if not, some of the yeast won't carry out matabolic reactions which won't turn the indicator colourless. As for which you use, glucose or sucrose, it doesn't really matter; just pick whichever one you prefer.

How are you going to be testing the effect temperature has on yeast; colorimeter, microscope and haemocytometer etc.? This will determine when to add the methylene blue indicator.

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Post by flyingbarbie » Sat Apr 28, 2007 2:59 pm

what would the results table be...all i can come up with right now is a simple table with the different temps and the colour change...but this wont be useful in graph form...any suggestions?

is it enough to write about how enzymes work for the hypothesis or do we need to mentions the fermentation of yeast?

dee88
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Post by dee88 » Sat Apr 28, 2007 3:01 pm

hi fanks for replying. im gonna be using microscope, so am i right to suggest that methylene blue would be put on to the slide above yeast suspension? is the concentration i'm using for yeast correct cause its been debated whether its 0.1% or 0.01% at which you can see the no. of yeast clearest. Also how much of the methylene blue do you need to put on and how would you go about calculating the % of yeast is it neccessary to be able to view all yeast cells under microscope?

How come evryone is putting the methylene blue into the yeast solution before heating and then adding the glucose?

dee88
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Post by dee88 » Sat Apr 28, 2007 3:08 pm

what would the results table be...all i can come up with right now is a simple table with the different temps and the colour change...but this wont be useful in graph form...any suggestions?

is it enough to write about how enzymes work for the hypothesis or do we need to mentions the fermentation of yeast?




im sure its not the colour change you need to be plotting but the % of cells you can see. Also i think its the enzymes you need to be talking about fermentation involves anaerobic respiration and the plan is not based on that

flyingbarbie
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Post by flyingbarbie » Sat Apr 28, 2007 3:17 pm

i would think adding a few drops of the yeast/glucose solution to a slide and then adding a couple of drops the meth blue to it will be fine
under the microscope, count the number of cells which r clear and those which r blue...from there u can calculate the % of the total cells which were blue

when i was carrying out my prelim work i was told that using a microscope would not be necessary and that just observing a colour change in the test tube would be fine....but using a microscope would make more sense as u can derive a %, which would go on the graph

have u done ur hypothesis?

Ulbrid
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Post by Ulbrid » Sat Apr 28, 2007 3:19 pm

dee88 wrote:How come evryone is putting the methylene blue into the yeast solution before heating and then adding the glucose?


Because they're silly. :wink:

I'm not sure about the concentration of yeast in the suspension; all i've mentioned is that it's a yeast suspension, and that's it.

Once you heated the sugar solution and yeast suspension to the desired temperature, use a pipette and put one drop of the mixture into a haemocytometer slide (or a normal one, if you so wish). Once you put a coverslip on, put 2 drops of methylene blue at one end of the coverslip (again, using a pipette). Then, once there's 2 drops (they should be just on the edge of the coverslip, they will begin bleeding into the yeast and sugar solution. You can speed up this process by holding a bit of tissue the other end of the coverslip, which will help pull the solutions through.

There are 2 ways you can calculate the percent of living yeast using a microscope. If using a normal slide, you can just count the living and dead yeast cells at any given magnification and, using ratios, calculate the percentage. Alternatively, if using a haemocytometer, you can count the amount of living and dead yeast cells in a given amount of space; this will be more precise because you actually have a specific area in which the yeast cells can be counted.

I hope this has been of some help. If you have any more questions, just ask. :wink:

dee88
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Post by dee88 » Sat Apr 28, 2007 3:29 pm

im at work now but im sure il have some more questions when i begin to write it up be sure to come back on at 8 :D

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