effect of temperature on the survival of yeast cells

[lleyew_Acissej]

Right... im writing this up as well and i havent a clue what im ment to do with the glucose or surcrose.... why do i need it??
Im not the brightest of people so please put it as simply as you can.

and has anyone any idea what temp they should denature at cos i thought most enzymes denature at roughly 42 degrees C

Thank you

[tallboy101]

I hadn't thought about diluting to reduce the number to count. but if you're going to dilute you'd have to do it from the start so that each sample used came from the same start point, this is to keep the only variable being temperature. A problem I see with this is to what degree do you dilute? A haemocytometer has the advantage of just shifting to a section where the amount is managable and use that size throughout the exp.

If the sample tested changed from a blue colour to a clearer colour then the yeast is still respiring, so it would not have been denatured at 70 degrees. However I was looking at 70 as being my upper limit and putting in the evaluation that the temperature may not be high enough.

[teek22]

In this investigation I will be using baker’s yeast similar to brewer’s yeast. I need to plan an investigation to find the lowest temperature that kills all the yeast cells in a suspension to either dried or fresh baker’s yeast.

My planning must be based on the assumptions that I am provided with the following:

• 10% suspension of yeast
• 10% solutions of sucrose or glucose
• 1.0% methylene blue solution
• School or college laboratory resources.

I need to give full details of my plan which needs to include:

• Apparatus and materials to be used
• Detailed method to include procedures that I would adopt to ensure that the results obtained were as precise and reliable as possible
• A risk assessment and safety precautions.

I need to indicate briefly how I would present and analyse my data to draw conclusions.

Hey can I just say look it up you bloody self, you have done the exact same with the physics coursework you lazy bum, stop getting other people do your coursework for you!! Also you see on the sheet where it says Declaration by student: Where you sign to say this is my work!! Then make it your work! Ever heard of something called research!

[Classified Information]

I was thinking of using a colorimeter to measure the light intensity afterwards to see how many dead blue cells there were, but then i thought that when there are less dead cells, the yeast lets very little light through anyway, so it wouldn't really work very well, so if i diluted it to a set amount each time, and then used the colorimeter, to see how much red light or whatever was absorbed by the dead blue cells... would that work?

[fhsen]

If the sample tested changed from a blue colour to a clearer colour then the yeast is still respiring, so it would not have been denatured at 70 degrees. However I was looking at 70 as being my upper limit and putting in the evaluation that the temperature may not be high enough.

what i meant was that when i started i tested dead yeast first of all to see the intensity of the blue colour. when i tested the yeast around 75degrees the solution remained blue but not AS blue as the dead yeast solution, if that makes sense..what i assumed is if i viewed that through a microscope there would still be many cells unstained

do you reckon that using a haemocytometer would be acceptable in your experiment? considering it says school laboratory equipment because i reckon using one would be easier too. how many sqaures would you use. i thought maybe about 0.6mm by 0.6mm (thats like 3 by 3 of the small squares)

[fhsen]

you could possibly dilute it after as long as you make sure that you dilute each solution equally.

[iwantthatbrat]

since we don't actually have to carry out the experiment you don't need a haemowhatever you can just say you'd count the cells on a normal microscope - i did the prelim today and tried it and you can see them fine. if we had to actually do the experiment then maybe you wouldnt bother but since we dont actually have to...

you don't need to sya youd dilute it either since you can see the cells fine if the microscope is properly focused

and some people on here are a bit pathetic asking how to do the whole thing. its not that difficult. like that other guy said - research it yourself!

[tallboy101]

since we don't actually have to carry out the experiment you don't need a haemowhatever you can just say you'd count the cells on a normal microscope - i did the prelim today and tried it and you can see them fine. if we had to actually do the experiment then maybe you wouldnt bother but since we dont actually have to...

you don't need to sya youd dilute it either since you can see the cells fine if the microscope is properly focused

and some people on here are a bit pathetic asking how to do the whole thing. its not that difficult. like that other guy said - research it yourself!

having to count cells without losing track isn't always easy!
I HAVE done some research but sometimes its good to bounce ideas off other people. I do agree that there are lazy people on here who just want an easy life, that is why i've only discussed the analysis.

[lleyew_Acissej]

i have done some prelims but i only have to write it up (the plan thingy some people are going on about) we had dry yeast....
we diluted with 5cm3 of water and this seemed to do the job.... i know that the cells are defo dead at 70 degrees C however im a little stuck when it comes to putting the sugar and the yeast together.... i put them together before i heated but it didnt do much and someone said if you put the glucose in after heating it wouild cool it down so i thought if you heat both and them add them together would that be fair?
ALSO the solution didnt go clear. it went back to the yeast colour... is that what is suppose to happen???



AND...... Is yeast an enzyme or a bacteria?.......

[fhsen]

lol yeast is a fungi

and also its not that we dont have to do the experiment but we have to make it as accurate as possible

[lleyew_Acissej]

Ok... but yeast has enzymes that can be denatured? or how does the whole denature thing come into it?

cos so far i have being doint the denature thing with the hydrogen bonds breaking menaing the secondary and tertiay structures lose their shape, becoming random coils so the substrate can no longer bind..... so... is this wrong for yeast?

[lleyew_Acissej]

ok to post a ulr i have to post 5 posts.....