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

The effects of temperature on catalase in yeast and liver.

Extracts from this document...


Introduction & Theory: As stated in the headline, this will be a plan to investigate the effects of temperature on the enzyme catalase in yeast and liver. But before I go in to detail about the experiment itself, the biology behind the reaction should be discussed. Starting with what will in great part control the reaction, some knowlegde of the biology of enzymes should be obtained. As we have learned, enzymes may be described as globular proteins with catalytic properties. They cannot cause reactions to occur, but only speed up ones which would otherwise take place more slowly. While the enzyme molecule is normally larger than the substrate molecule it acts upon, only a small part of the enzyme, called the active site, actually comes into contact with the substrate. It is commonly accepted that the enzymes operate on a socalled lock and key mechanism. The lock and key mechanism works in the way that in same way as a lock fits a key, the substrate fits exactly into the active site of the enzyme molecule. There, the substrate is either split into two or more molecules, or two or more molecules may be joined together, as with dipeptide. During the entire process, the enzyme remains unchanged and maintains its initial shape. This allows it to keep turning sustrate into products, being used over and over again. The rate at which enzymes normally work can be shown on a graph as a rapid increase at first, as there is plenty of substrate for the enzymes to bump into and turn into product. At a point though, the reaction will reach its peak. A maximum number of substrate is being turned into product per second/minute. ...read more.


The yeast and liver will be homogenised and used as a yeast/water and liver/water suspension. One reason for doing this is to secure an even enzyme concentration. If we were to use single cut pieces, a piece cut from the center of the yeast/liver may have higher enzyme concentration than one in the outer edges. The best way of keeping this a fair test is in other words to make a suspension, using for instance 1g liver and 50cm3 water. Mixing the sample of yeast/liver will make possibly different enzyme concentrations blend in together. Also, dried yeast ages more quickly, becoming denatured and deteriated. Another important factor is to use the same yeast or liver throughout the entire experiment. If we were for instance to suddenly use a new, fresh piece of yeast, this could contain a higher concentration of enzymes than the original. Seeing as a higher concentration of enzymes would produce more substrate at a quicker rate, this would make the experiment inaccurate. Another necessity in order to make this a fair test is in other words to use the same sample of yeast/liver throughout the experiment. As for the substrate, we need to use the same concentration and volume for all samples. The way in which we can make sure of this is to make out one mixture of H2O2, for instance 50 cm3, and use fractions of this for all the samples. The opposite, making new concentrations for each sample would make this variable anything but constant. Changing the concentration would affect the results, as a higher or lower concentration would produce different amount of products at different speeds. Important for both is to keep a constant volume. ...read more.


Hydrogen peroxide is not flammable. 10 C 20 C 30 C 40 C 50 C 60 C Yeast Liver Yeast Liver Yeast Liver Yeast Liver Yeast Liver Yeast Liver Initial volume (cm3) Table: Table of initial volume of water in burette: Table of temperature vs rate of oxygen gas release 10 C 20 C 30 C 40 C 50 C 60 C min sec Volume (cm3) No of bubbles Volume (cm3) No of bubbles Volume (cm3) No of bubbles Volume (cm3) No of bubbles Volume (cm3) No of bubbles Volume (cm3) No of bubbles 30 1 1 30 2 2 30 3 3 30 4 4 30 5 5 30 6 6 30 7 7 30 8 8 30 9 9 30 10 Area where error could occur: * Volume of gas emitted exceeding that of the burette's volume, oxygen gas escaping into free air. This would make further readings impossible, and the final volume could not be recorded. * The bung might not be fitted tightly enough into the boiling tube and oxygen gas might leak out through the space between the bung and the sides of the boiling tube. All results obtained would be inaccurate. * Oxygen gas might also be lost if it the pipette misses the opening of the burette. In that case, the gas would rise to the surface of the water outside the burette. Inaccurate readings would be the result. Method to avoid this: * Be wary not to use too large amounts of hydrogen peroxide, 5 cm3 should be enough to observe a reaction. Also be careful to fill the burette with as much water as possible. * Fit bung tightly into the boiling tube, taking care that no oxygen gas escapes. * The pipette must be kept directly under the opening of the burette, preventing the potential loss of the oxygen as the reaction is taking place. ...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

    An investigation to examine the effects of temperature on membrane stability in beetroot, by ...

    3 star(s)

    From this I can conclude that the permeability of the cell surface membrane is affected by the temperature of the environment that it is in. If the temperature falls too low, the cell membrane freezes and dies, so becoming more permeable.

  2. Does ethanol causes greater inhibition of pig liver catalase than of yeast catalase

    I will choose beads with a 5mm diameter. I will measure each bead with a ruler to make sure it is right. Pilot Experiment To complete my experiment I must find out a reasonable strength of hydrogen peroxide to use.

  1. The effect of Copper Sulphate concentration on Catalase activity on Hydrogen Peroxide.

    If I stirred the contents of each test tube such problem could have perhaps been avoided. Reliability of results: Overall I consider my results to be reliable, as I did a number of repeats which values didn't extremely differ from each other.

  2. Catalyse Investigation

    This meant that it was the substrate and not the enzyme that was at the required temperature. When the sucrase was added, the extra volume in the boiling tube would have meant that the temperature would have dropped slightly. The enzyme would have been reacting with the substrate before its

  1. Investigate how concentration of the enzyme catalase in celery tissue alters the rate of ...

    collected in the time indicated Reading 1 Reading 2 Volume of Oxygen Gas produced (cm3) Concentration of Celery Extract % 1 min 2 min 3 min 1 min 2 min 3 min 100 12.8 15.2 18.4 None Achieved - 75 8.3 11.1 14.3 None Achieved -

  2. Investigating the effect of the Temperature on the Enzyme Catalase when it reacts with ...

    For example I could investigate the different tissue e.g. liver and try to find out the optimum temperature of the catalase enzyme within a mammalian body. However there are many different enzymes, which are always present in a mammals and in our body, all these enzymes have a different chemical properties.

  1. This is an experiment to show how different concentration of celery tissue enzyme, catalase ...

    This means large amount of hydrogen peroxide will be broken down. Consequently, as the enzymes breakdown hydrogen peroxide there will be little left of this substrate, resulting in the high amount of oxygen. I think if the enzyme concentration is doubled from 25% to 50% concentration the amount o oxygen produced will also double.

  2. An investigation to see how different concentrations of aspirin affects hydrogen peroxide breakdown by ...

    There should be adequate ventilation when working with hydrogen peroxide, and there should be easy access to an ample water supply for thorough flushing of accidental spillage on surfaces and on people. Hydrogen peroxide is a non flammable liquid, however the decomposition produces oxygen that is flammable.

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