Section 2.4 &2.5: Enzymes - PowerPoint Presentation

Slide1

Section 2.4 &2.5: Enzymes

Slide2

To the penny placed on your desk.

Observe the penny but don’t touch it. What happens?

Explain why

2. Give the penny a

little

push. What happened?

Why did the penny move the second time and not the first time?

What was added the second time and not the first time?

Slide3

Energy is neither created or destroyed, it continues to be transferred.

All Chemical reactions involve a change/transfer in energy.

Chemical Reactions Release and Absorb Energy

Potential Energy

Potential to Kinetic Energy

Potential Energy

Potential Energy

Slide4

Observing a Chemical Reaction

Put 50 mL of water into a flask

Add 10 drops of

Bromothymol

Blue

(

an acid indicator which will turn the solution

yellow if an acid is present)

Get the temperature in `C.Add one Alka

Seltzer tablet (split into two)Observe reaction and write down observations

Get the temperature after the reaction occurs.What you observed was:

CO

2 + H2O H2CO3 (Carbonic Acid) Reactants Product

Slide5

Energy is needed to start a Chemical Reaction

Activation Energy

is the amount of energy that needs to be absorbed to start a chemical reaction

The push to get the boulder to go down the hill

Activation Energy

Slide6

Do you have this bottle at home?

What is it?

What is it used for?

Can you keep it in your medicine cabinet forever?

Why?

Hydrogen Peroxide

Disinfecting a wound

NO!!

It will naturally break down into Water and Oxygen

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What happened when the Manganese Dioxide was added to the 3% Hydrogen Peroxide?

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What happened when the Manganese Dioxide was added to the 30% Hydrogen Peroxide?

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How can we reduce the amount of activation energy needed to get a reaction started?

2H

2

O

2

2H

2

O + O2

This reaction will occur on its own but will take a long time and a lot of activation energy

Catalysts reduce the amount of activation energy necessary to get a reaction started

This is a method of cleaning contact lenses using a Manganese dioxide disk which will quickly break hydrogen peroxide into water in oxygen and get your contacts totally disinfected!!The Manganese dioxide disk can be used over and over again without a loss of functioning.

Slide10

A Chemical Reaction with and without a catalystThe Catalyst

decreased the amount of activation energy needed to get the reaction started

a catalyst

a catalyst

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Does anyone suffer from eating…?

…Beans, peanuts, broccoli, cauliflower, Brussel sprouts, cabbage, peppers, onions…

?

You know what I am talking about!!!

This happens because we can’t digest

alpha-galactose

present in these foods There is something to prevent this!! Beano contains the

Enzyme alpha-

galactosidase to allow us to break down alpha-galactose

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What is the name of the sugar found in milk? Maybe you can’t tolerate lactose sugar and are lactose intolerant.

What do people do who are lactose intolerant?They take Lactaid pills which contain the enzyme

Lactase

We will do a lab on this

Enzymes

are

protein catalysts

made by living organisms that

reduce the amount of activation energy necessary to start and control the rate of a chemical reaction

Lactose

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Our cells always produce Hydrogen Peroxide. 2H

2

O

2

2H

2

O + O2

This is highly toxic to our cells.An enzyme called catalase

will allow hydrogen peroxide to quickly break down to water and oxygen. You have seen this with a cut and blood when you put hydrogen peroxide on it.

One catalase molecule can convert 40 million of molecules of hydrogen peroxide to water and oxygen each second

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Characteristics of Enzymes

Made up of

Proteins

Are specific

to whatever they act upon

Are

reusable

– don’t get used up in a chemical reactionUsually have names ending in “ase

”Enter directly into a reaction

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How Enzymes workTheir shape is specific to what they act upon (the

substrate

)

They will bind directly to the

substrate

as an

enzyme-substrate complex

The binding site is called the

Active SiteA substrate and its enzyme fit together like puzzle pieces –

Lock and Key Theory

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Slide17

Substrate

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What can influence an enzymes reactivity?

Temperature

Since enzymes are proteins, their structure can be changed or destroyed by high temperatures.

As temperature increases, the rate of enzyme activity increases to a point then quickly decreases.

Study Island Virtual lab

In us, this temperature is at ~ 40`C

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pH Too high or too low pHs will effect the enzyme activity and possibly change its shape.

Lactase activity virtual lab

Different for different organs

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Concentration of enzymes As the number of enzymes increases, the rate of reaction increases also to a point

where all the enzymes are already bound to an active site of a substrate.Additional enzymes won’t speed up a reaction at this point.

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ReviewTo which biomolecule group do enzymes belong to and usually end in …?

2. What is an enzyme?

What do enzymes do?

4. What part of the enzyme enters into a reaction?

Proteins, -

ine

Organic catalyst

Controls the rate of a reaction

Active Site

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What is the term used for the molecule which is acted on by the enzyme?When the two are together, what is it now called?

What will extreme pH’s and temperatures do to the active sites of enzymes?

What is the ideal pH and temperature for most reactions in our body?

Enzyme-Substrate Complex

Denature the active site – Change the shape

~6.5 – 7.4 & 37`C

Substrate

Slide23

Label the diagram using the terms, Product, substrate, enzyme, active site and, enzyme-substrate complex.