Help with lab project [Effect of low pH on Enzyme Activity]

[normy]

I am supposed to do a lab experiment that shows The Effect of low pH on Enzyme Activity. I will be using yeast as a catalase enzyme and hydrogen peroxide as a substrate. I was going to use vinegar, bleach and distilled water for pH levels but I am not sure if that is right. The project isn't about any pH level but low pH. It is supposed to test the effect of an acidic fluid on enzyme activity. I started thinking that maybe I should just use vinegar to test it and distilled water. I plan on using the distilled water as a control. Does it make sense to just put distilled water with peroxide and no enzyme? The more I think about it, the more confused I get.

Edited October 6, 2015 by normy

[hypervalent_iodine]

Firstly, bleach won't give you a low pH. It's basic. Some also contain peroxides.

 

Could you give a little more context about what you're doing? Why are you adding household chemicals instead of dilute HCl? Surely this will complicate the number of variables you are changing? How are you determining enzyme activity? Are you using purified enzyme or yeast cells? What are your controls?

[normy]

Okay, I have been going over everything and trying to get everything right. This is what I have so far.

Materials

3% H2O2

Vinegar

Yeast (Pack of yeast bought at the grocery store)

pH test strips

2 test tubes

balloons

 

I would put 1/4 tsp yeast in one test tube. Then I would put 3 mL of water in one test tube and 3 mL of vinegar in the second test tube with vinegar. Swirl the test tubes. I would let that sit for 10 about 10 minutes while I measured the circumference of the deflated balloons using a string and ruler. I would then add 3 mL of 3% peroxide into each balloon. Without spilling the peroxide into the tube, I would wrap the neck of the balloon around the test tube top. When both test tubes are ready, I would then spill the peroxide into the test tube and swirl the tubes. I would then observe the tubes for reaction for at least two minutes. Then I would wrap the string around the center of each balloon to measure the circumference and record my measurements.

 

I am not sure how to prepare a dilute HCI. I was thinking that the water would be a control group because it does not have yeast in it.

[BabcockHall]

I don't see dilute HCl in your protocol. Dilute is a little bit vague, but remember to add commercial HCl to water to prepare it, not the other way around.

[John Cuthber]

Ordinary "chlorine" bleach reacts with hydrogen peroxide.

 

While it is good practice to dilute acids by adding them to water,it doesn't matter which way round you do it with HCl.

 

It might be interesting to try using an alkaline material (perhaps bicarbonate of soda) to see what effect that has.