I placed the yeast filled test tube into a water bath. These baths were spread across the classroom and were at different temperatures. I left the tube in the bath so I would be sure that the temperature would stay the same and not go back to room temperature. Before I started my experiment when I placed the tube into the water bath I left it for 1 minute before I took any readings. I did this because in the first minute of when it gets into the hotter water, the air is expanding so the bubbled produced may not be bubbles of carbon dioxide.
I think that at room temperature, there will be little or no respiration because the enzymes just aren’t active at such a low temperature.
FERMENTATION is the breakdown of sugars by bacteria and yeast using a method of respiration without oxygen (anaerobic respiration). It involves a culture of yeast and a solution of sugar, producing ethanol and carbon dioxide with the aid of the enzymes.
This process can be slowed down by DENATURATION of the enzymes at a certain temperature.
All the ENZYMES are protein chains of amino acids. Along the chain there are active sites where interaction between the enzyme and the substrate happens. These sites are sensitive to heat, like the hydrogen bonds that hold the 3D molecule together. When heat is applied to the enzyme, energy is given into the molecule. The active sites deform and the hydrogen bonds break, denaturing this enzyme. It would not be able to function as usual, and this is not reversible. This is called DENATURATION. The analogy of this is to compare a key to a keyhole. If the keyhole has changed, the same key would not fit in any more, and the lock would not be unlocked. The same thing happens here, and fermentation could not continue after this has occurred. Also when the temperature is too low, the enzymes would not work because there is not enough energy for activities to happen.
Diagram-
Results
Bubbles of carbon dioxide Produced
Conclusion
The outcome of the experiment was just as I predicted. This is that the rate of respiration would increase do a certain level then stop due to the enzymes becoming denatured.
The enzyme collision rate as the temperature rose was steady up until the bonds of the enzyme breaking.
My results show that it increases up until the enzymes reach there optimum temperature, then rate of carbon dioxide bubbles produced goes down.
From the successful experiment- I can conclude that temperature is a factor that does affect the rate of respiration in enzymes.
Evaluation
I think my experiment went as successfully as it possibly could.
I think I did the experiment enough times to draw out a clear average then draw out a line of best fit. On the graph, the amount of carbon dioxide produced went up as the temperature went up. It rose straight away and after 40 degrees, it started to fall due to the denatured enzymes unable to produce carbon dioxide as efficiently as the previous temperatures. In this case, an inverted ‘u’.
If I were to do the experiment again I would take more readings to get even clearer results. I would also take more regular temperatures, like every 30, 30.25, 30.5 etc. just to get a clearer idea of the optimum temperature of the enzymes.