## Quiz #9

$V_{0} = \frac{V_{max}[S]}{K_{M} + [S]}; K_{M} = \frac{[E][S]}{[ES]}$

melissasandoval2O
Posts: 24
Joined: Fri Jul 15, 2016 3:00 am

### Quiz #9

Hello ya'll!
Can someone please explain to me how number 9 is done? Since Dr. Lavelle stated we should know how to do this one, I'm hoping someone can show me!
Thanks!

AnkitaNair1E
Posts: 17
Joined: Wed Sep 21, 2016 2:55 pm
Been upvoted: 1 time

### Re: Quiz #9

Hi Melissa,

So for #9 they give you four options and we need to find the incorrect one. Let's go through them together.

a) When the concentration of the substrate is low, the rate of an enzyme-catalyzed reaction increases with the concentration of the substrate.
This one is true because essentially we need to remember that usually the reaction rate is determined by the amount of reactant we have (in this case substrate), hence all the reasons for the first and second rate laws. The only time that the rate isn't determined by the concentration of the reactants is when you have a limited amount of catalysts and you have more product than enzyme. If you run into this scenario, then the rate is determined by the enzymes not the concentration of the reactants because the enzymes will get saturated and will limit the rate of the reaction. But in this case, the problem specifically tells us that we have a low substrate concentration so we can conclude that the rate is directly proportional to the concentration of reactant. So an increase in concentration leads to an increase in rate.

b) When the concentration of the substrate is high, the reaction rate only depends only on the concentration of the enzyme.
So we kinda went over this in the explanation of A but this one is true because usually our body has a limiting amount of enzymes so when we have too much product, our enzymes become saturated. At this point, the rate is determined by how much enzyme you have NOT how much reactant you put in.

c)All enzymes are proteins
This one is true because the structure of an enzyme is a protein. If you want more information about it, I definitely encourage you to study the biology behind this.

d)All proteins are enzymes
So this is the tricky one. Basically what you have to remember from biology is that protein have 5 main functions: enzyme/catalyst activity, movement, defense, structure, and transportation. Because we have such a diverse amount of proteins in our body, we know that not all proteins are going to be enzymes. So you can conclude this choice to be the false one.

Hope this helped!

melissasandoval2O
Posts: 24
Joined: Fri Jul 15, 2016 3:00 am

### Re: Quiz #9

^^^^ That is such an amazing explanation! Thank you so so sooooo much!!!!