Catalyst speeds up chemical reaction and its factors affecting the chemical reaction.

1. Catalysts

2.  Note: For all the questions
in this PPT, write your
answer on a 1 whole sheet
of paper).

3. Catalyst
 A catalyst is a substance that
increases the rate of a chemical
reaction. The presence of a catalyst is
one of several factors that influence
the rate of chemical reactions. (Other
factors include the temperature,
concentration, and surface area of
reactants.)

4. Catalyst- substance that causes a
chemical reaction to happen more quickly
(speeds up).
A catalyst isn’t a reactant in the chemical
reaction it speeds up. As a result, it isn’t
changed or used up in the reaction, so it
can go on to catalyze many more
reactions.

5. How is a catalyst like a
tunnel through a mountain?

6. Chemical reaction- activation of energy
is needed for the transformation of
molecule into usable one.
Activation energy- a minimum amount
of energy required to convert a reactive
one. is the energy needed to start a
reaction. When activation energy is
lower, more reactant particles have
enough energy to react so the reaction
goes faster.

7. The catalyst brings the reactants together by
temporarily bonding with them. This makes it
easier and quicker for the reactants to react
together.

8. Enzymes
 are biomolecules that catalyze (i.e.
increase the rates of) chemical
reactions
 are catalysts in living things
 More than 1000 different enzymes are
necessary for human life.

9. Substrate- the reactant on
which an enzyme acts.
Active site- surface of an
enzyme whose shape permits
binding only a specific molecular
substrate.
Denatured- when enzyme loses
its structure and becomes non-
functional due to changes in
temperature and pH.

10. An example is amylase, which is found in the mouth
and small intestine. Amylase catalyzes the breakdown
of starch to sugar. You can see how it affects the rate
of starch digestion in the Figure below

11. If you chew a starchy food such as
a soda cracker for a couple of
minutes, you may notice that it
starts to taste slightly sweet. Why
does this happen?

12. Naming Enzymes
 End in –ase
 Identifies a reacting substance
sucrase – reacts sucrose
lipase - reacts lipid
 Describes function of enzyme
oxidase – catalyzes oxidation
hydrolase – catalyzes hydrolysis
 Common names of digestion enzymes
still use –in
pepsin, trypsin

13. Classifications of Enzymes
Class Reactions catalyzed
 Oxidoreductoases oxidation-reduction
 Transferases transfer group of atoms
 Hydrolases hydrolysis
 Lyases add/remove atoms
to/from a double bond
 Isomerases rearrange atoms
 Ligases combine molecules
using ATP

14. Examples
 Oxidoreductoases
oxidases - oxidize ,reductases – reduce
 Transferases
transaminases – transfer amino groups
kinases – transfer phosphate groups
 Hydrolases
proteases - hydrolyze peptide bonds
lipases – hydrolyze lipid ester bonds
 Lyases
carboxylases – add CO2
hydrolases – add H2O

15. Learning Check 1 (Write your
answer on 1 whole sheet of
paper)
Match the type of reaction with the
enzymes:
(1) aminase (2) dehydrogenase
(3) Isomerase (4) synthetase
A. Removes 2 H atoms to form double
bond
B. Combine two molecules using ATP
C. Adds NH3

16. Enzyme Action:
Lock and Key Model
 An enzyme binds a substrate in a region
called the active site
 Only certain substrates can fit the active
site
 Amino acid R groups in the active site
help substrate bind
 Enzyme-substrate complex forms
 Substrate reacts to form product
 Product is released

17. Lock and Key Model
+ +
E + S ES complex E + P
S
P
P
S

18. Enzyme Action:
Induced Fit Model
 Enzyme structure flexible, not rigid
 Enzyme and active site adjust
shape to bind substrate
 Increases range of substrate
specificity
 Shape changes also improve
catalysis during reaction

19. Enzyme Action:
Induced Fit Model
E + S ES complex E + P
S
P
P
S
S

20. SOME INDUSTRIAL USE OF
ENZYMES
Application Enzyme Uses
Dairy industry Rennin
Lactase
Coagulant in cheese
production
Hydrolysis of lactose-
free milk product
Brewing industry Protease, amylase,
cellulase
Breakdown of starch
and proteins, prevent
cloudiness in stored
beers
Biological detergents Protease, lipase,
amylase
Removal of organic
stains such as gravy, oil
and saliva
Baking industry Amylase
Protease
Breakdown of starch,
production of maltose
Breakdown of proteins

21. SOME INDUSTRIAL USE OF
ENZYMES
Application Enzyme Uses
Leather industry Protease Removal of hairs
from hides
Paper industry Ligninase Removal of lignin
from pulp
Pharmaceutical and
medical industries
Lysozyme
Trypsin
Urokinase
Antibiotic
Removal of dead
tissues from
wounds and burns
Dissolves blood clot
after a heart attack

22. According to some European Sports
Medicine reports, there is scarcely a
atop athlete in Germany who is not
familiar with enzyme therapy. Top
Austrian athletes, runners, wrestlers,
boxers, hand ball players and skiers
are provided with enzyme capsules
as a precaution to aid in rapid
recovery after injury

23. Learning Check 2
A. The active site is
(1) the enzyme
(2) a section of the enzyme
(3) the substrate
B. In the induced fit model, the shape of
the enzyme when substrate binds
(1) Stays the same
(2) adapts to the shape of the substrate

24. Factors Affecting Enzyme
Action: Temperature
 Little activity at low temperature
 Rate increases with temperature
 Most active at optimum
temperatures (usually 37°C in
humans)
 Activity lost with denaturation at
high temperatures

25. Effect of Temperature
 40 °C – optimum/optimal temperature
 20 °C – inactive
 60 °C – enzyme is destroyed

27. Factors Affecting Enzyme
Action: pH
 Maximum activity at optimum pH
 R groups of amino acids have
proper charge
 Tertiary structure of enzyme is
correct
 Most lose activity in low or high pH

28. Reaction
Rate
Optimum pH
3 5 7 9 11
pH

30. Factors Affecting Enzyme Action:
Substrate Concentration
 Increasing substrate concentration
increases the rate of reaction
(enzyme concentration is constant)
 Maximum activity reached when all
of enzyme combines with substrate

31. Factors Affecting Enzyme
Action
Maximum activity
Reaction
Rate
substrate concentration

32. Learning Check 3
Sucrase has an optimum temperature of
37°C and an optimum pH of 6.2.
Determine the effect of the following on
its rate of reaction
(1) no change (2) increase (3) decrease
A. Increasing the concentration of
sucrose
B. Changing the pH to 4
C. Running the reaction at 70°C

33.  Directions: Choose the letter of your
choice.
1. How does a catalyst work in speeding
up a reaction?
a. by lowering the activation energy or
reaction
b. by giving them more energy
c. by making them more available
d. by increasing the amount of reactant

34. 2. The minimum amount of energy
needed for colliding particles to react is
called the
a. Chemical Energy c. Activation
Energy
b. Kinetic Energy d. Potential
Energy

35. 3. A substance that increases the rate of
a reaction without being used up during
the reaction is called a
a. Catalyst c. reactant
b. Product d. solute
4. Catalysts permit reactions to proceed
along a ___________energy path.
a. lower c. the same
b. higher d. constant

36. 5. A catalyst increases the efficiency of
collisions between reactants.
a. true c. it depends
upon the reactant
b. false d. no relationship
at all
6. What is the name given to a catalyst in
the human body?
a. Biology c. Chemical
b. Catalyst d. Enzyme

37. 7. When a catalyst is added to a reaction
the rate of reaction ________.
a. Increases c. Does not
change
b. Decreases d. Is constant
8. A catalyst is __________ in a reaction.
a. used up c. limited
b. never used up d. obtained

38. 9. A catalyst be regenerated or used
again and again
a. False
b. True
c. It depends on the amount of the reactant
d. No relationship at all

39. 10. A catalyst changes the mechanism of
the reaction
a. True
b. False
c. It depends on the amount of the reactant
d. No relationship at all

40. THE END