ExergonicVs

Endergonic?

Endergonic: Building

Exergonic: Breakdown

Enzymes: Proteins that are used for chemical reactions(some RNA molecules)• Enzymes can either break up or put

together substrates • Enzymes are specific – only work on

certain substrates.• Enzymes are biological catalysts that

react on substrates• Enzymes are NOT CHANGED in the

reaction

Catalyst:

A substance that causes a reaction to occur but does not itself get changed

Biological catalysts (enzymes) are found in ALL living cells

How do enzymes affect chemical reactions?

Enzymes are catalysts which speed up the reaction by lowering the activation energy required, thus making it efficient for sustaining life.

Activation Energy

The energy required for a chemical reaction to start and continue on its own.

Similar to rolling a boulder downhill, it is the chemical ‘push’ that gets a chemical reaction going.

(Enzymes lower the activation energy needed for chemical reactions. Less energy needed to start the reaction, can occur at lower temperatures.)

Liver, Potato Cells…Hydrogen

Peroxide

Lowering the

Activation Energy

How an enzyme works…

Substrate: A substance that the catalyst (enzyme) acts on

Ex) Lactose = milk sugar (substrate) Lactase = breaks down lactose

(enzyme)Active Site: The specific

region of the enzyme that combines with the substrate

Liver/Potato Demo- Reaction? Enzyme? Multiple collisions…

forever??

“Induced Fit”- stress on substrate bonds, weakens them…less AE needed

(text p 162,166)

Lock and Key:

The lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).

Factors that affect the rate of Enzyme Action:

Temperature: There is an optimum (best) temperature that each enzyme works in . Increase temperature, increase molecule movement, increase rate of the reaction.

Temperature too LOW, decrease the effect of the enzyme

Temperature too HIGH- Protein Denatures (breaks down/changes shape)- the enzyme will not work.

Denatured EnzymeWeakened H-bonds….Alpha/Beta… unravels

Enzyme Regulation:

Factors that affect the rate of enzyme actionA cell can regulate enzymatic activity by controlling the amount of enzyme produced

Allosteric Sites (Feedback Inhibition)

A cell can regulate enzymatic activity by controlling the amount of enzyme produced

Noncompetetive vs Competetive Inhibition

Factors that affect the rate of Enzyme Action:

TemperaturepHConcentration: Increasing the amount of enzyme will

increase the rate of reaction, but it will eventually level off- why?

For the same reason, increasing the substrate concentration will increase the rate of reaction, but it will eventually level off.

SEE ALL GRAPHS ON PAGE 3 of the Enzyme Packet

Enzyme Animation

http://www.biotopics.co.uk/other/hienz.html

http://www.kscience.co.uk/animations/anim_2.htm