• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

An investigation to find the lowest temperature that kills all the yeast cells in a suspension of bakers yeast.

Extracts from this document...


An investigation to find the lowest temperature that kills all the yeast cells in a suspension of bakers yeast. Contents Page 1 - Hypothesis and introduction Page 2 - Introduction, risk assessment Page 3, 4 - Risk assessment, Pilot study (method, results, conclusion and evaluation) Page 5 - Variables, Equipment list Page 6 - Equipment list, Precision and accuracy, final method Page 7 - Final method Page 8 - Intended treatment of results, References Page 9 - Evaluation of references Hypothesis This investigation involves studying the fungi, yeast, to see how it responds to different temperatures. Based on the effect high temperatures will have on the enzymes of the yeast a sensible prediction would be that higher temperatures, above the optimum, around 50�C would kill yeast cells. Introduction Yeast is a unicellular, eukaryotic, fungus and as so generates energy from respiration as shown below in this simplified equation. Inside the yeast cell enzymes control this reaction. Enzymes are globular proteins which act as biological catalysts maintaining vital reactions such as respiration. Temperature is a major factor that affects the rate of an enzymes activity. As the temperature increases so does the kinetic energy that both the enzymes and substrates possess; which means there will be a greater number of enzyme - substrate collision and thus a greater rate of reaction. ...read more.


Evaluation This was strictly a preliminary experiment as there were many aspects which make it simply a guideline for a further experiment. Firstly there was only one test tube for each temperature meaning it was not an average reading which is far more accurate. The other flaw was that just saying whether or not the yeast was dead or alive seemed unsatisfactory. By means of a counting chamber, it would be possible to discover how much yeast survived in a particular area. However as a preliminary experiment it served its purpose as it gives an approximate suggestion to where yeast enzymes are denatured, which means a more suitable range of temperatures can be used. Variables - Dependent and Independent My independent variable is the single variable I will adjust in order to study the effect it has on the experiment is the temperature of the water bath the test tubes of yeast and glucose and submerged in. The dependent variable is the percentage of yeast alive at the end of the experiment, which is by my prediction directly proportional to the temperature. Constant Variables * Concentration of yeast - Changing how much yeast is present in 0.5cm�of solution each time would give a useless value for the percentage alive. ...read more.


12. Shake the test tubes and then use another pipette to remove a few drops of the solution and place it on three slides and cover with slips. 13. Carefully place the slides under an electric microscope, focus it and examine the slides. 14. Using a counting chamber of 1cm� measure how many yeast cells are alive in this area. 15. Take the mean for how many cells remain alive in this area. 16. Repeat stages 5 to 16 for 40�C, 45 �C, 50 �C, 55 �C and 60 �C. Intended treatment of results Once the experiment is completed I will process the results into a table. -A table to show the percentages of yeast cells alive at various temperatures- Temperature/�C % of yeast alive Average % of yeast alive Run 1 Run 2 Run 3 35 40 45 50 55 60 The first average where 100% of the yeast cells are killed gives the lowest temperature where all yeast dies. By studying the range and uncertainty it can give an approximation to how accurate the results are and account for any significant anomalies. This means that if a significant anomaly is detected it can be disregarded or re -run to account for the random error. References Resource Format Biology 1 (OCR) pages 42 -47 Book Collins advanced science - biology pages 90 - 94 Book http://en.wikipedia.org/wiki/Enzymes Website www.ubi.ca/cart/images/images/enzymes.JPG Website www.examstutor.com/biology/resources/studyroom/biochemistry_and_cells/enzymes/pictures/temperature/.gif Website http://en.wikipedia.org/wiki/Respiration_%28physiology%29 Website http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enzymes. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    The Effect Of Temperature on the Respiration Of Yeast.

    5 star(s)

    This will be the same up to about 45oC. At 45-50oC I predict that the rate of reaction will be high and the enzymes will be working very fast and also denaturing therefore the TTC solution will turn from colourless to pink quickly.

  2. Investigation to find the effect of glucose concentration on fermentation of yeast.

    4 cm? 0.8M glucose solution 4 cm3 0.6M glucose solution 4 cm3 0.4M glucose solution 4 cm3 0.2M glucose solution 4cm3 0.0M distilled water 2cm3 of phenolphthalein To see how long it will take for the phenolphthalein to become colour less, from purple alkali colour to colour less acidic solution.

  1. An experiment to find of the isotonic point of root vegetables cells in contents ...

    This in turn should increase the accuracy and precision of my results. Another error which may have occurred was that when placing the lids back on the McCartney bottles, I may not have placed the lids properly on some of the bottles and this may have caused evaporation to occur resulting in some solution becoming more concentrated.

  2. Investigating the Effect of Temperature on Rate of Respiration in Yeast

    Some of the main enzymes are dehydrogenase enzymes and decarboxylase enzymes, the dehydrogenase enzymes take hydrogen and pass them onto NAD molecules, or simply let them stay in the matrix, and wait to be bonded with an oxygen molecule. Another important enzyme is ATP synthetase, which synthesises ATP from ADP.

  1. The aim of this investigation is to find out how concentration of glucose affects ...

    This graph shows how rate of reaction is affected by pH: 6. I will try to control enzyme concentration by using the same amount of yeast (4g per 100ml of water). However there may be different amounts of enzymes in some yeast cells and more yeast cells will be active

  2. A Level Biology revision notes

    its RNA and reserve transcriptase into the cytoplasm * Reverse transcriptase copies viral RNA strand * This forms a double stranded viral DNA in the nucleus of T-helper cell / now called "provirus" * Viral DNA is integrated into the host DNA / host cell replicates with provirus * Latency period (variable period of time)

  1. The effect of temperature on the survival of yeast cells

    respiring anaerobically, heat energy is produced because fermentation is an exothermic reaction which provides yeast with energy for its metabolism. Anaerobic respiration is the oxidation of molecules in the absence of oxygen to produce energy; Glucose Lactic acid + Energy (ATP)

  2. Investigation to find the lowest temperature that kills all the yeast cells in suspension ...

    Accurate to +/- 0.4cm3, more accurate then a measuring cylinder (+/-1cm3) Boiling tube rack (x3, as each one only holds 5) - To stand the boiling tubes in. Thermometer- This is needed so cross checks of the temperature of each substrate can be made before mixing.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work