Substrate concentration Practical - Hydrogen peroxide and Liver (1 Viewer)

[Kujah]

I've typed up a mock method of how to go about doing this. It involves adding different quantities of 5% hydrogen peroxide mixed with distilled water, and uses 1g of fresh liver for each test tube. The result is obtained by measuring the height of the bubbles of oxygen formed when liver and the solution mix, and this gives us an indication of the enzyme activity of catalase.

My question is, how could I improve the design of the experiment?

 

[Survivor39]

Ok, rather than measuring the height of the bubble formed, can you use a more scientific approach to measure the products form?

Afterall, you are trying to show that additional substrates, in the presence of catalase, allow the enzyme to produce more products up to a certain substrate concentration. So how much products were formed - quantify it? And what is the range of substrate concentrations have you used? Can you use more concentrations?

 

[marwa990]

Hey;

u should consider the following experimental improvements:
1. Placing 10 liver pieces in the 10 test tubes containing different concentrations of H2O2 amd starting timing is not accurate as u cant gurantee that the liver pieces came in contact with the solution at the same time. A better approach is to experiment with 2 testtubes at a time or alternitavley do one test tube at a time and after a specific time start measuring height of O2 froth.
2. Furthermore, its more valid to seal the testtubes to ensure the O2 bubbles dont escape into atmosphere.
3. do repeats to increase reliability and validity.
4. be careful with timing and use a mm ruler for accuracy.

 

[xiao1985]

Just a point on the safety side of the things.

Sealing any reaction which evolve gases can be quite dangerous. As gas builds up and can (potentially) explode.

 

[Undermyskin]

Actually be aware of the rather reactivity of this H2O2 'cuz in our experiments, we got a trouble with the bubbles spilling over the test-tubes. It's like bubbles you make when washing yourself actually. lolz. So, the amount of liver should be decreased, I guess or the tube tests used should be larger in size. (this doesn't help 'cuz the bubbles still floated over) BTW, I suggest you should put the H2O2 stuff into each test-tube only after you finish putting the liver and measuring the previous bubble height already. (to increase the validity, I think) otherwise the O2 and H2 formed will be lost. I got troubles like that which startled me a while in the prac test. Hope these help.

 

[xiao1985]

Oh, one more safety thing. Hydrogen peroxide is a strong oxidant. Avoid contact with skin, etc. It should also be handled in dark where possible.

 

[Kujah]

Cheers!