Unit 5 1/2
A chemical reaction will
occur spontaneously…
but the process may be
too slow to be effective,
in living
cells…
A chemical reaction will
occur spontaneously,
but the process may
be too slow to be
effective,
in living
cells…
ex. hydrolysis of sucrose:
adding water~
they break apart
ex. hydrolysis of sucrose:
energy is required to
break the bond between
those two carbohydrate
molecules,
ex. hydrolysis of sucrose:
+ adding water~
they break apart
Chemical reactions can’t “get
started” w/o energy being added
• In other words…
ENERGY must be
added in order for the
reaction to start…
• Kinda like you cannot
put keys on a ring…
without opening the
ring first!
ex. hydrolysis of sucrose:
energy required to break
bonds = Activation
Energy
it is EXTREMELY
HIGH!
ex. hydrolysis of sucrose:
Activation energy!!
ex. hydrolysis of sucrose:
Activation
Energy - -
the reaction can occur
only when energy is
ACTIVATION ENERGY
can give off heat
hydrolysis of molecules in
your body…
Energy of Activation EA
barrier is EXTREMELY
high - the reaction will
occur only if reactantsed:
Energy of Activation EA
barrier is EXTREMELY
high - the reaction will
occur only if reactants are
heated:
Enzymes lower the
temperature of the activation
Energy
energy
- of
Activation EA
barrier is
EXTREMELY
high - the
reaction will
occur only if
reactants are
heated:
Enzymes lower activation energy
so rxn. can occur Too hot!!!
AHHHHH!!!
Enzymes lower activation
energy this allows chemical reactions to
happen in your body FASTER!!
Bromelai
n
Pineapple has been used as a medicinal plant in several native
cultures and bromelain has been known chemically since 1876.
Bromelain is a digestive enzyme found in the stem and fruit of
the pineapple plant
DURKEE meat tenderizer has BROMELAIN
Papai
n
Its utility is in breaking down the tough meat fibers and has
been utilized for thousands of years in its native South
America.
It is sold as a component in powdered meat tenderizer
available in most supermarkets.
The cheap meat tenderizer had PAPAIN
This is an enzyme called
CATALASE
It’s active site
The substrate enters the
ezyme’s active site
Enzymes are specific to
the molecule with which
they attach (substrate)
Enzyme
molecule it attaches with
Stages of an enzyme-catalyzedreaction:
catalase
H2O2
Stages of an enzyme-catalyzedreaction:
catalase
H2O2
Stages of an enzyme-catalyzedreaction:
Stages of an enzyme-catalyzedreaction:
catalase
H2O
O2
Energy
released
Energy
released
Energy
released
Energy
released
Enzymes are affected by
environmental factors:
ex. pH
Energy o
Beyond that temp, speed
of reaction drops:
Enzymes do have
optimal pH:
Improper pH disrupts
bonds in the protein
…remember, enzymes
are PROTEIN
Enzymes are affected by
environmental factors:
ex. temperature
Enzymes are affected by
environmental factors:
ex. too cold
Enzymes slow
down
They cannot
Enzymes are affected by
environmental factors:
ex. amount of heat
Acceptable
temperature…
PERFECT
Too hot…
DENATURED
hmmm… WHAT would that
do to the active site?
Too hot…
DENATURED
Enzymes do have
optimal temperatures:
heat disrupts bonds in
the protein
…remember, enzymes
are PROTEIN
Sometimes enzymes
require nonprotein
“helpers”
Molecules that are bound to the active site
CoEnzymes
“A cell is not just a bag
of chemicals with
thousands of different
kinds of enzymes and
substrates wandering
about randomly.”
Control of metabolism-
Chaos would result if all of
a cell’s metabolic
pathways were open at the
same time… chemical
reactions must be regulated
Cattle-ist