Effect of Temp on Yeast Cells

Bio coursework

Methylene blue

Yeast cells - explanation of respiration hence colour change etc

Low temp colour change should be visible as the yeast cells are not necessarily dead, just inactive.

Activity increases from 20-45 c

High rate around 30-40

Starts to slow down - basically enzyme curve see bio 1

100 degrees will kill all cells

Do a few preliminary keep working down until first blue solution appears in unit of ten

Then work to find degree. If more accuracy then half a degree.

Show method to do this. Waterbath etc

Methylene blue

It can also be used as an indicator to determine if a cell such as yeast is alive or not. The blue indicator turns colourless in the presence of active enzymes, thus indicating living cells

A simple table with the temperature in one column and whether or not the cells survived

pick a high temp, then a low temp, then pick a point in between and iterate.

ten test tubes each in a water bath with 10 degree intervals should give you a rough idea, then once you have the test tube with the highest temperature that's still colourless (the methylene blue indicator) you can heat it up one degree at a time and find the exact temperature that kills the yeast cells

To multiply and grow, all yeast needs is the right environment, which includes moisture, food (in the form of sugar or starch) and a warm, nurturing temperature (70o to 85oF is best).

Intro

As a living organism yeast needs sugars, water and warmth to stay alive.

which ferments the sugar in cereal (saccharo-mucus cerevisiae) to produce alcohol and carbon dioxide'

Baker's yeast is produced from the genus and species of yeast called Saccharomyces cerevisiae. The scientific name of the genus of baker's yeast, Saccharomyces, refers to "saccharo" meaning sugar and "myces" meaning fungus

The typical yeast cell is approximately equal in size to a human red blood cell and is spherical to ellipsoidal in shape. Because of its small size, it takes about 30 billion yeast cells to make up to one gram of compressed baker's yeast. Yeast reproduce vegetatively by budding, a process during which a new bud grows from the side of the existing cell wall. This bud eventually breaks away from the mother cell to form a separate daughter cell. Each yeast cell, on average, undergoes this budding process 12 to 15 times before it is no longer capable of reproducing. During commercial production, yeast is grown under carefully controlled conditions on a sugar containing media typically composed of beet and cane molasses. Under ideal growth conditions a yeast cell reproduces every two to three hours

Some yeasts have the ability to carry out an alcoholic fermentation. Other yeasts lack this property. In addition to the fermentative type of metabolism, fermentative yeasts