Lab 1 Enzyme Catalysis 10.20.16

2H2O2 -------------> 2H2O + O2 Enzymatic reaction is very important for everyone including Turnip Sad Turnip Happy Turnip Turnip Peroxidase  2H2O2 -------------> 2H2O + O2 Enzymes' activity is important for every organisms. One important aspect of enzymes is to regulate the rate of the reactions. Sometimes, cells want the reaction to be fast; but there are also times cells want the reaction to be slow. Because enzymes are proteins, of which the activity can be altered by the environmental conditions (like pH or temperature), cells would use this property to change the activity of enzymes by changing the environmental conditions (how?). The change of enzyme’s activity would lead to the change of the reaction rate.

+ Reaction of small molecules (i.e. H2O2) Reaction of big molecules (proteins) Enzymes can catalyze reaction of small molecules; it can also catalyze reaction between big molecules including proteins, which happens quite often in cells. Protein complex AB Protein A Protein B Enzymes Polymerase +

“Microtubule” filament “Microtubule” filament “Microtubule” filament Microtubules are the enzymatic reaction product of tubulins short “Microtubule” filament Nucleus (DNA) Microtubules tubulins tubulins Enzymes Polymerase + Long “Microtubule” filament short “Microtubule” filament Microtubules are like bones of the cells. Small subunits proteins called tubulins are assembled into microtubules to support the cell functions. But they are also very flexible so that they can be disassembled (or have lower assembly rate) for changing the “cell motility” (like our bones, though we use flexible alternative called joint for our motility instead of disassembling our bones). tubulins Polymerase + Polymerase is an enzyme

“Microtubule” filament “Microtubule” filament Microtubules growth can be affect be temperature Long “Microtubule” filament short “Microtubule” filament So the assembly rate of microtubules also needs to be regulated. One factor that can affect the rate is the temperature. The higher the temperature is, the higher the assembly rate is (not too high, because tubulins are proteins) , which also means the longer microtubules would be. tubulins High T + Low T

What you will see in cells when looking at microtubules Pay attention to the length of the bright tubule-like signal in the movie (S.Pombe is yeast)! https://www.youtube.com/watch?v=ygatgSfi8U8 In case that you cannot view the movie here. S.Pombe is a single-celled organism. The bright lines in this movie are microtubules which were made to be visualizable. See what would happen when temperature is shifted from 25 degrees to 5 degrees?

“Open Inquiry” What conclusion you can make from the movie? What is the thing that you see in the movie that can be measured if that is an experiment? If you were the scientists that have these cells, what do you want test next? pH? Oxygen level? Inhibitor?....