Transcript (enzyme).

Enzymes:
Proteins that are used
for chemical reactions
• Enzymes can either break up or put together
substrates
• Enzymes are specific – only work on certain
substances.
• Enzymes are catalysts that react on substrates
• Enzymes are NOT CHANGED in the reaction
Textbook
pages: 78-81 Figure 5-5 on pg. 80
You will be responsible for all definitions on pages 1 & 5 of the
enzyme packet, and should be able to interpret the graphs on
Page 3 of the packet.
Definitions:
 Proteins:
Biochemical
compounds (macromolecules)
made up of long polymer chains
of amino acids linked together
 Catalyst: A substance that
causes a reaction to occur but
does not get changed itself
Definitions:
 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
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).
Lactose is a 2-unit
sugar. Lactase
breaks it into 2
individual sugars:
glucose and
galactose.
Can it break down sucrose as
well? Why or why not?
Factors that affect the rate
of Enzyme Action:
 Enzymes
work best at certain:
–Temperatures
–pH
–Concentrations
(See Graphs- Page 3 of Enzyme Packet)
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 Enzyme
Factors that affect the rate
of Enzyme Action:
 pH: Enzymes work best at different pH
levels depending on where they are.
Page 4- Enzyme Packet: Relative Rate
of Enzyme Action.
 pH Scale?
 Acidic = 0 – 6.9
Basic = 7.1 – 14
 #3- Enzyme A- pH of the stomach?
 #4- Enzyme B- pH of the intestine?
Factors that affect the rate
of Enzyme Action:
Concentration:
 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
Activation Energy
The energy needed to start a chemical
reaction.
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.

Activation Energy
Endothermic: Building
Activation Energy
Exothermic: Breakdown
Enzyme Animation
http://www.biotopics.co.uk/other/hienz.
html
http://www.kscience.co.uk/animations/a
nim_2.htm
How Enzymes Work



The active site (location on the enzyme where the
substrate fits and the reaction takes place) on the
enzyme attaches to a substrate molecule
While attached to the substrate, the enzyme either
breaks or makes a bond, resulting a change to the
substrate
Ex) Carbohydrate broken into sugars
Amino acids bonded to make protein
The enzyme is not changed during the reaction
and is free to break-down more substrates
CAPT LAB: ENZYMES



Comparing the effectiveness of cellulase and
pectinase in making juice.
You will investigate which enzyme or
combination of enzymes will remove more juice
during the process of making apple juice from
applesauce .
Once you complete the lab, you will evaluate
which enzyme will be the most cost effective
plan to use in juice production.
CELLULOSE



Large carbohydrate
Composes the cell walls of plants
Tough and fibrous – provides structure
to plants
CELLULASE


The enzyme that breaks down
cellulose
The optimum pH generally lies
between 4 and 5
Pectin


Large carbohydrate found in plant cell
walls
Sticky substance used to bind plant
cell walls to each other and hold
cellulose in place
Pectinase



Enzyme that breaks down the pectin in
plant cells
Used to produce fruit juice and wine
Optimum pH is 4-5
CAPT Lab:
Cellulase v. Pectinase
Enzymes?
 Pectinase and Cellulase
Substrates?
 Apple Sauce
CAPT LAB: Purpose

To determine which enzyme, or
combination of enzymes, will produce
the most juice for the least cost