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

Find the effect of temperature on anaerobic respiration of yeast.

Extracts from this document...

Introduction

Introduction We wanted to find the effect of temperature on anaerobic respiration of yeast. We investigated how a mixture of yeast, water, sugar, and flour were affected. Diagram Apparatus 1g of yeast 0.5g of sugar 10g of flour 6 measuring cylinders - to put the sachets in and the 20cm3 of water Measuring cylinders to measure the water Thermometers - to keep the same temperature in the water baths Water baths - at 20�C, 30�C, 40�C, 50�C, 60�C Hot air oven - at 70�C Beakers - to use to put the yeast mixture in the cylinders. Method We set up the apparatus as shown, and placed 1g of yeast, 0.5g of sugar, and 10g of flour each into the beakers. Then we added 20cm3 of water, measured with a measuring cylinder, and stirred the mixture until there were no bubbles left in it, and it was a smooth paste. Then the volume of the dough in each was 25cm3 and we poured it into 6 measuring cylinders. Then we placed the 4 cylinders in 10�C, 30�C, 40�C, 50�C and 60�C in water baths at those constant temperatures, maintained with a thermometer. Then we left a cylinder at room temperature (20�C) and the last in a hot air oven at 70�C. ...read more.

Middle

A chemical reaction always involves a substrate changing into another. The substance, which is present in the beginning of the reaction, is called the substrate. The substance, which is made by the reaction, is the product, e.g. ethanol + CO2 from glucose and yeast. Enzymes have a very precise 3D shape, and each has a "duct" and has exactly the right size and shape for a molecule of the enzyme's substrate to fit into it. This "duct" is known as the active site. When the substrate slots into the active site, the enzyme "tweaks" the substrate molecule, by pulling it out of shape and making it split into product molecules. These then depart from the active sit, which is then ready to repeat the process with another substrate molecule. Most chemical reactions happen faster when the temperature is higher. At higher temperatures, molecules move around faster. This makes it easier for them to react together. Usually a rise of 10�C will double the rate of the reaction. They are very sensitive to high temperatures. Once the temperature is above 100�C, the enzyme will be damaged. When this occurs, it cannot catalyze its reaction so well, so the reaction slows down. The water rehydrated the powdered yeast, sugar, and flour mixture, so it gave the enzymes a solution to work in. ...read more.

Conclusion

These are due to the problem we had with the uneven temperatures, in which the measuring cylinders with dough were in, as it was relatively difficult to maintain the temperatures in the water baths, as we continuously had to put some hotter or colder water into the baths. However, the results were reliable and accurate to support the conclusion, which also agreed with my hypothesis. As the temperature increased, the volume of the dough increased until it reached its peak, and the enzymes had reached their optimum temperature. Then the volume decreased because the enzymes were denatured. I hav creatd another experiment which investigates the best temperatures at which yeast enzymes work best at. I want to investigate further into what exactly is the yeast enzymes' optimum temperature, as it was 101cm3 at 50C, but as I mentioned before - the dough was at unevern temperatures, as it was hard to control it without the special abilities of laboratory machines. I know that the optimum temperature is between 40C and 50C. Method We will mix 1g of yeast, 0.5g of sugar, and 10g of flour, each in 4 beakers with 20cm3 of water, which will be measured with a measuring cylinder. Then we will pour it into measuring cylinders, but this time using a measuring cylinder with a larger opening, to avoid spilling the mixture around the edges of it. Then, the volumes in each of the 4 cylinders will be 25cm3 ...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

    Investigating respiration of maggots

    5 star(s)

    Therefore if the water bath heats up the rate will rise and vice versa, and once again the rate would not be constant. By repeating the experiment these factors can be accounted for. ___ Risk Assessment During my investigation there are various safety issues that I must abide by to ensure my experiment is safe.

  2. Marked by a teacher

    The Effect Of Temperature on the Respiration Of Yeast.

    5 star(s)

    At the end of glycolosis the product made, pyruvate still has a lot of chemical potential energy left over. When there is free oxygen available, some of this energy can be released via Krebs cycle and oxidative phosphorylation. If under anaerobic respiration, pyruvate gives off CO2, ethanal, which is then, reduced to ethanol.

  1. Marked by a teacher

    Investigating the Effect of Ethanol Concentration on the Rate of Respiration in Yeast.

    3 star(s)

    These are then converted to Pyruvic Acid by NAD molecules being reduced to NAD + H+. In these processes, 2 ATP molecules are formed and 2 Pyruvate molecules. The Link Reaction is the next stage in respiration. This occurs in the mitochondria of the cell.

  2. WHAT EFFECT DOES SUBSTRATE HAVE ON THE RATE OF RESPIRATION IN SACCHAROMYCES CEREVISIAE?

    There are three types of enzymes I need to know about; digestive enzymes, transport enzymes and respiratory enzymes. Digestive enzymes: are enzymes which work to break down larger molecules into smaller molecules. The 'induced fit theory' explains how enzymes can catalyse the breakdown of substrate molecules in a reaction.

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

    The first ATP causes the hexose sugar to be turned into hexose phosphate, and the second ATP molecule makes it hexose bisphosphate. Phosphorylation raises the energy of the glucose, and reduces the activation energy barrier for the pathway. After phosphorylation, the hexose bisphosphate is split into 2 other identical molecules of triose phosphate.

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

    The amount of yeast will have an effect on the rate of reaction, as the yeast contains the enzyme (zymase), so if I increased the amount of yeast the rate of reaction will take place in a different way it could be both slower and faster.

  1. Investigate how temperature affects the rate of anaerobic respiration in a sucrose & yeast ...

    This indicated that not only are enzymes affected by heat, but that they also are inclined to catalyse the reaction much more rapidly at higher temperatures. Another experiment shown as an example in the Key Science Biology textbook showed that pepsin (an enzyme that catalyses the breakdown of proteins)

  2. Investigation to discover the effect of temperature on anaerobic respiration in yeast cells.

    Yeast can respire using oxygen, this is known as aerobic respiration and releases up to 20 times more energy that fermentation or anaerobic respiration. However the investigation that I wish to proceed with does not require aerobic respiration, therefore I will coat the surface of the yeast solution with a

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