Download Enzymes - Guided Notes - Flip-Flop

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Name:_________________________ Period:_________ Date:____________________
Enzymes: Biological Catalysts for Chemical Reactions
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All chemical reactions begin with chemical
reactants that are then changed into different
chemicals called products. The order of the
reaction is indicated with an arrow, which points
from reactants to products:
H2O2

H2O
+
O2
Reactant 
Product
Product
-----------------------------------Here’s a reaction – the one for photosynthesis:
H2O +
CO2
 C6H12O6 + O2
(water) + (carbon dioxide)  (sugar) +(oxygen gas)
----------------------------------------------------------------------Here’s one more – the reaction for respiration: 
C6H12O6 + O2
 H2O +
CO2
(sugar) + (oxygen gas)  (water) + (carbon dioxide)
---------------------------------------------------------------------How to tell if a chemical reaction has taken place:
1) Change in temperature;
2) Change in color; or
3) Formation of a gas
-----------------------------------------------------------------All chemical reactions need some energy, called
activation energy, to get them started (get “over
the hump/hill”). The bigger the hill, the more
activation energy it takes to get it started.
It will be hard for a reaction with a large
activation energy to ever happen.
H2O2

H2O
+
H2O2 = hydrogen peroxide
H2O = water
O2 = oxygen gas
O2
How many reactants are there? ______
How many products are there? _______
----------------------------------------------------------------- What is/are the reactant(s)?
What is/are the product(s)?
--------------------------------------------------- What is/are the reactant(s)?
What is/are the product(s)?
Looking at the reactions above what would be a definite
way (from the list at left) to tell if those reactions had
occurred?
------------------------------------------------------------------------
*1*That is why living things have enzymes, which
are proteins that act as catalysts. Catalysts are
things that speed up chemical reactions.
*2*Enzymes speed up chemical reactions by
lowering the activation energy (hillspeed bump),
so that less energy is needed to start the reaction.
*3*Enzymes are NOT “used up” or altered by the
reaction – they are reused/recycled over and over.
Notes
Trace over the reaction with a higher activation
energy in blue. Trace over the reaction with the
lower activation energy in red.
Which line do you think represents the reaction
that involved an enzyme?
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Enzymes speed up reactions by binding (attaching)
one or more reactants of a reaction to a spot on
the enzyme called the active site.
Example of enzyme
and its substrate:
The reactant(s) that binds to an enzyme are called
the substrates.
*4*Enzymes catalyze one specific chemical
reaction since only that substrate(s) has the right
shape to bind to the active site [“Lock & Key”]
If something happens to change the shape of an
active site, it will no longer fit the substrate and
the reaction may slow or stopl!
*5*When an enzyme loses it’s shape, it is said to be
“denatured.”
---------------------------------------------------Re-read the previous page to refresh your
memory and then write the definitions of the
bolded words on the other side:

---------------------------------------------------Enzymes are affected by
1.
2.
3.
Enzymes typically function best (optimal) within a
narrow range of ___________&____________?
Circle what could
be the substrate for
the enzyme shown
here:
a.
b.
c.
d.
---------------------------------------------------Chemical reaction –
Activation energy –
Enzymes –
Catalyst –
Active site -
Substrate –
Denatured ---------------------------------------------------A + B + C  ABC
What is the optimal pH for each enzyme??
What can cause an enzyme to Denature??
1.
2.
---------------------------------------------------You saw how a fake enzyme called ABCase (most
enzyme names end with “ase”) catalyzed the
reaction A + B + C  ABC

Notes
What is/are the reactant(s)/substrates?
What is/are the product(s)?
What’s the name of the enzyme?
What was special about its shape?
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Notes
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