Download UNIT 2: The Chemistry of Life

UNIT 2: The Chemistry of Life
Biology I
DAYSHEET 23: Introduction to Enzymes
Name _____________________________________
Date: __________
Bellringer:
Directions: Use your reading strategies (underline, highlight and/or circle) as you review the
passage below.
pH & Solutions Active Reading:
In class, we discussed three types of solutions: Acids, Bases, and solutions that are Neutral. How do
we determine whether a solution is an acid, base, or neutral? That’s easy, we use the pH scale! The
pH scale is a linear scale that runs from 0-14. Look at the scale below:
0 --------------------------------------------------7-----------------------------------------------14
Acid
Base
Neutral
Substances with a pH below 7 are called Acids. Substances with a pH above 7 are called Bases.
Substances with a pH of 7 are called Neutral.
We need to add one more detail to this scenario: The pH scale actually measures the amount of
HYDROGEN IONS (H+) that are present in a solution. The lower the pH value, the greater the
amount of hydrogen ions (H+) present in the solution.
Example: Solution A has a pH of 8. Solution B has a pH of 3. Because Solution B has a lower pH, it
has a greater concentration of hydrogen ions present. The more acidic a solution is, the greater the
concentration of hydrogen ions.
1. An unknown solution has a very high concentration of hydrogen ions present. Is this solution
an acid or a base? _____________________________
2. Most household cleaning products have a very high pH. Are most household cleaning products
acidic or basic? ___________________________
3. What is the only substance discussed in class that has a neutral pH?
_______________________________________
Biology Objective: I understand that enzymes are necessary for maintaining metabolism and
homeostasis in all living things
Homework: HW23 due next class
Activity 1: Cornell Notes
Name:
Period:
Date:
Biology Objective:
Essential Questions
#1: What is an
enzyme?
#2: How do enzymes
work?
#3: How does an
enzyme’s shape help it
speed up reactions?
Notes:

Enzymes are a type of _____________________________

Enzymes are made of _____________________________

Enzymes are __________________ = things that speed up chemical reaction

Enzymes work by lowering ___________________________ energy= the
energy needed to get a reaction started

Lowering activation energy ______________________ chemical reactions!

Complete the graph below to show how enzymes work:

_____________________ = the molecule(s) an enzyme attaches to

____________________________ = part of the enzyme that fits the substrate

An enzyme fits onto its substrate like a _____________________________

Label the following in the above picture: enzyme, substrate, active site
Summary:
ructure of a water molecule by filling in the blanks below!
Directions: Use the graph below and your notes and answer the questions
1
2
1. Which letter(s) on the graph represent(s) the activation energy? ________
2. Which line (1 or 2) on the graph represents a reaction with an enzyme? _________
3. Which line (1 or 2) on the graph represents an uncatalyzed reaction? ________
4. What do enzymes do?
FLIP
Lysosomes are responsible into breaking down food
FLOP
What is the function of the lysosome?
molecules into even smaller molecules the cell can
use for energy. They also help break down waste
and old parts in the cell.
Each cell contains many lysosomes. Each lysosome
has specific molecules inside that help break down
different substances. These molecules are called
enzymes.
Enzymes are proteins that act as catalysts. A
catalyst is something that speeds up a chemical
What do enzymes do?
What are enzymes made of?
A. monosaccharides
C. amino acids
B. fatty acids
D. nucleotides
reaction.
Write what type of molecule the following enzymes
All enzymes have the ending “ase” on their name,
and you can usually tell what they break down by
looking at the first part of their name. For
example, lactase breaks down lactose, a sugar
probably break down:
Lipase breaks down ________________
Protease breaks down _______________
found in milk.
All chemical reactions need some energy, called
activation energy, to get them started. Some
reactions don’t need much energy, while others
need a lot. If a lot of activation energy is needed
to get it started, it will be hard for the reaction to
ever happen.
That is why living things have enzymes. Enzymes
speed up chemical reactions by lowering the
activation energy, so that not as much energy is
needed before the reaction can get going.
Trace over the reaction with a higher activation
energy in one color. Trace over the reaction with
the lower activation energy in another color.
Which line do you think represents the reaction
that involved an enzyme?
FLIP
Enzymes speed up reactions by holding molecules in
FLOP
Example of enzyme
and its substrate:
place while they are joined together or broken
Circle what could be the
substrate for the
enzyme shown here:
apart. At the start of a reaction, the enzymes
a.
binds (attaches) to a specific molecule, called the
substrate. The specific spot on the enzyme that
attaches to the substrate is called the active site.
b.
As long as the enzyme is in good shape and can fit
to the substrate, it will be a lot easier for the
substrate to come together OR split apart.
c.
d.
Why might the relationship between an enzyme and
its substrate be compared to a “lock and key?”
If something happens to an enzyme to mess up its
shape, it will no longer fit the substrate and the
What does it mean if an enzyme is “denatured?”
reaction may happen very slowly or not at all! When
an enzyme loses its shape, it is said to be
“denatured.”
Why might this happen? Well, all enzymes have
specific temperatures and pHs where they work
What might cause an enzyme to denature?
best. If the temperature or pH gets too high or
too low for that enzyme, the enzyme could
denature.
The enzyme ABCase catalyzes the following
reaction:
What will happen to ABCase if the temperature
rises to 40 degrees Celsius?
ABC  A + B + C
ABCase works best at a temperature of
35 degrees Celsius and a pH of 7 (neutral).
What will happen to ABCase if the pH becomes
more acidic (lower)?
HW 23: Enzymes
Name: ______________________________
Biology I
Date ___________________
Enzymes & Chemical Reactions: Use your reading strategies to receive full credit for your
work.
Organisms must be able to quickly turn reactants in a chemical reaction into product. This
speed helps to ensure proper metabolic function, which maintains homeostasis. This is a key
characteristic of life! In class, we discussed speed bumps and their role regulating the speed of
traffic on busy streets. Remember that speed bumps are designed to slow traffic down. We
have a similar “bump” in biology! Although speed bumps are necessary when regulating
traffic, they can be deadly in living things. The body must be able to lower these “bumps” to
ensure that our chemical reactions happen as quickly as possible.
Enzymes are special proteins designed to lower these “bumps.” In chemical reactions, these
bumps are called ACTIVATION ENERGY. The higher the activation energy, the slower the
chemical reaction! Enzymes increase the rate of chemical reactions by making these chemical
speed bumps smaller. If a chemical reaction has an enzyme present, it is a CATALYZED
reaction. Catalyzed reactions will always proceed faster than uncatalyzed reactions.
1. Which statement about enzymes is true?
a.
b.
c.
d.
Enzymes are consumed during chemical reaction.
Enzymes provide energy to activate a chemical reaction.
Enzymes provide a site on which reactants can combine.
Enzymes increase the concentration of reactant particles.
2. How are enzymes able to speed up biochemical reactions?
a.
b.
c.
d.
They provide energy to the reactants.
They absorb energy from the products.
They lower the activation energy of the reaction.
They increase the number of available reactant particles.
Look at the graph below to answer questions 3-6.
3. Which of the chemical reactions has a lower activation energy in the graph above, the
catalyzed or the uncatalyzed reaction? ______________________________________
4. Which of the chemical reactions (catalyzed of uncatalyzed) in the graph above will
happen at a faster rate? _____________________________________
5. Which of the chemical reactions above (catalyzed or uncatalyzed) has an enzyme
present? _________________________________
6. Using the graph above, which chemical reaction will have a lower activation energy
(with enzyme or without an enzyme)? ___________________________________