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An investigation into the effects of temperature on the rate of anaerobic respiration of yeast

Extracts from this document...

Introduction

'An investigation into the effects of temperature on the rate of anaerobic respiration of yeast' Sadaf Chezari Risk assessment: Risk: Hazard: Method of Minimizing Risk: Yeast solution Yeast can be an irritant when heated * Clean up spills immediately and keep all skin covered, e.g. wearing a lab coat. * If made contact with skin, rinse off immediately. * Make sure goggles are worn at all times throughout the experiment. Using a Bunsen burner Not knowing if the Bunsen burner is on or off when not in use Hair/clothes can catch the flame * Always leave Bunsen burner on safety flame when not in use * Turn the gas down and make sure the flame is not too big. * Long hair must be tied back and out of the way. * Remove any loose objects to avoid close contact with fire. E.g. I.D badges Boiling water Can cause third degree burns if spilt on skin. * Make sure the beakers which contain hot water (water baths) are all kept in the centre of the table and no objects are in the way to knock the beakers off the tripod stand. Hot apparatus Burn skin if in contact with skin * Use safety equipment to avoid contact with skin * Tripping over If there are bags lying around the room there is a risk of tripping over them. * Tidy away all bags and make sure there nothing left on the floor. Glass wear Can be easily broken * Place them at the centre of the table and not around the edge to avoid knocking them down. * Carry one piece of equipment at a time. * If there is any breakages, sweep up the debris immediately and dispose of it. * Hold equipment when cooled. Thermometer Dangerous if dropped, contains mercury and sharp glass. * Keep away from edges of table to avoid it rolling off. ...read more.

Middle

This is due to the fact that the enzyme controlled reactions of the yeast are identical to any chemical reaction- the more kinetic energy provided; the more rapidly the reaction will occur up to a point. Being a catalyst, after the reaction has occurred, the products are released and the active site remains unchanged to carry out further reactions. The measure of kinetic energy is approximately equal to the temperature applied to the system. Brooklyn Academic agrees and stated that 'the kinetic energy of the molecules can be converted into chemical potential energy' when molecules have collided enough times with the correct amount of energy. This chemical potential energy can help the system achieve the activation energy and more reactions can occur. The 50 �C water bath of yeast solution had a higher amount of kinetic energy due to the increased temperature. The higher the effect of kinetic energy to a system, the more chemical energy the substrate has, which gives it enough energy to collide with the enzymes active site and reach the activation energy. Also, there will be a higher amount of vibration of the particles so more collisions of particles so more reactions will occur. The vibrations of the particles in the water baths of lower temperatures will be less, thus less substrate would collide with the enzymes active site with enough energy for the molecules to break. The gradient of each reaction in the water baths of different temperatures are steepest at the beginning, for example; the Co2 production/ bubble length in the water bath at 35 �C grew most within the first 5 minutes, the gradient is 1.0mm/per minute, while at 30 minutes, the gradient has decreased to 0.2mm/per minute. This gives evidence that after a certain period of time, the rate of respiration by the yeast solution has shoed down in each water bath. This is due to the fact that there is more substrate available for reaction and also there being more available active sites free for the substrate to bind at the beginning of a reaction. ...read more.

Conclusion

This would ensure that all the preparations are the same and would give continuity. I would want to be more strict and thorough with preparing solutions and mixing them up. I would want each one to be thoroughly acclimatised to the surroundings and had the same amount of glucose and the same activating and mixing time. This would help give more reliable results throughout. Another alteration to my investigation would be changing the way in which I collected the gas. This would increase the accuracy of the results if they had a human error. This is because the measuring cylinder we used may not have been filled at a correct graduation mark and therefore the results would have been untrue as there would therefore have been human error of the results + or- a graduation mark. The yeast is converting sugar to ethanol and carbon dioxide- which causes the foam layer of carbon dioxide. This causes difficulty when measuring the bubble length with a ruler. To improve it, pipette solutions from under the foam layer into fermentation tube- push it down the side of the tube to prevent foam bubbles forming. This will increase reliability as the yeast solution will have its rate of reaction measured. Controlling 3 solutions of different temperatures consistent is very hard to keep up, to improve its best to use a thermostat water bath and cooler. This increases reliability as it is electronically controlled so able to ensure that the temperatures are stable, making the experiment more accurate and fair. Also safer not having to leave a Bunsen burner on while rushing to record the length of bubble. If I were to further investigate this experiment and my results, I would probably want to calculate the point where the enzymes begin to denature for respiration in yeast. I could also examine the change in rate between the intervals to determine validity and continuity. I would also have taken more results at each temperature interval as to increase the depth and accuracy of the results and therefore would help in achieving a better graph with a stronger correlation. ...read more.

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