Dispatch
1) Give 3 facts about enzymes
2) What does denature mean?
3) How are we going to denature our enzyme?
Announcements
• Next test Chapters 2-7. POK or chapter notes
• Pick up your grade report at lunch TODAY
• Meeting today after school so office hours after
school tomorrow
• To redo Ecology POK, turn in chapter notes
Take out prelab
Denaturing Enzymes
• Enzymes are proteins. Proteins are chains of
amino acids.
• Denature=weaken or kill an enzyme
by breaking the amino acid bonds.
• When an enzyme is denatured, it
slowly turns substrate to product or
not at all.
Animation
http://www.biotopics.co.uk/other/aninac.html
What can cause an enzyme to
denature?
Enzyme: Catalase
REACTANT
• H2O2
PRODUCTS
• O2
• H20
What is the equation of this reaction?
• http://bioweb.wku.edu/courses/Biol114/enzy
me/enzyme2.asp
Denaturing Enzyme
• Temperature--Each enzyme has
an optimum temperature at
which it works best; making the
enzyme too hot or too cold will
denature it.
Denaturing Enzyme
• The pH--Each enzyme has an
optimal pH that helps maintain its
three-dimensional shape; making
the enzyme too acidic or basic
will denature it.
Base
Acid
Denaturing Enzyme
• The salt concentration--Each
enzyme has an optimal salt
concentration; making the
enzyme too salty will denature it.
Your job is to denature an enzyme in
the lab and measure its rate of
turning a substrate into a product.
H202
Catalase
Water
Oxygen Gas
Catalase Lab pg 53
• Chicken liver has the enzyme catalase.
• The substrate is hydrogen peroxide (H2O2).
• The products are water (H2O) and oxygen gas
(O2).
catalase
2H2O2----------------------> 2H2O + O2
Materials:
• 5 test tubes
• 1 test tube rack
• 50 ml of catalase
• 1 ml lemon juice (acid)
• 1 teaspoon of salt
• 25 ml of H2O2
Control
Hot
Cold
(Temperature)
Acid
(pH)
Salt
Procedures pg 53 (cont)
Copy and draw each step
1. Label 5 test tubes: Control, Hot, Cold, Acid, Salt
2. Place 10 cm of catalase (enzyme) into each test tube.
3. Make 3 hypothesis, one for temperature, one for pH,
and one for salt.
If_____________then
If_____________then
If _____________then
4. Place the test tube labeled temperature in the hot water
bath for 3 minutes.
5. Place the test tube labeled cold in the cold water bath
for 3 minutes and the test tube labeled room
temperature leave in the test tube rack.
6. Add 1ml of lemon juice to the one labeled acid.
7. Add 1 ml of salt to the one labeled salt. Get approval.
8. Add 5ml of H2O2 (substrate) to each of the 5 tubes.
9. Time the reaction with the stop watch and record the
height of the bubbles in each tube in cm. Record in
Data Table.
Laboratory Safety
T-1-- Lab Room
5
6
7
8
2
1
BEFORE THE LAB
Dress properly during a laboratory
activity.
Long hair, dangling jewelry, and
loose or baggy clothing are a
hazard in the laboratory.
Long hair must be tied back, and
dangling jewelry and baggy
clothing must be secured. Shoes
must completely cover the
foot. No sandals allowed on lab
days.
Which shoe is appropriate?
Don’t touch, until told
When first entering a
science room, do
not touch any
equipment,
chemicals, or other
materials in the
laboratory area
until you are
instructed to do so.
Where’s the safety equipment?
Know the locations and operating procedures of
all safety equipment including: first aid kit(s),
and fire extinguisher. Know where the fire
alarm and the exits are located.
T-1: Fire Extinguiser is by the door, first
aid is by the whiteboard
No food
Do not eat food,
drink beverages,
or chew gum in
the
laboratory. Do
not use
laboratory
glassware as
containers for
food or
beverages.
Know the directions
Follow ALL written and
verbal instructions
carefully. If you do not
understand a direction or
a part of the procedure,
ASK YOUR TEACHER
BEFORE PROCEEDING
WITH THE ACTIVITY!
Before the Lab—Answer in complete
sentences
1) How do we dress for a lab?
2) What is the rule about food and gum?
3) Can you touch equipment before being
told?
During the Lab
Be responsible
Conduct yourself in a
responsible manner
at all times in the
laboratory.
Work together
Never work alone in
the laboratory.
No student may
work in the
science classroom
without the
presence of a
teacher.
Authorized experiments only!
Perform only those
experiments
authorized by your
teacher. Carefully
follow all instructions,
both written and oral.
Unauthorized
experiments are not
allowed.
Be preapred
Be prepared for your work in
the laboratory. Read all
procedures thoroughly
before entering the
laboratory. Never fool
around in the
laboratory. Horseplay,
practical jokes, and pranks
are dangerous and
prohibited.
Keep your area organized
Observe good housekeeping practices. Work
areas should be kept clean and tidy at all
times.
Don’t wander
Experiments must be personally monitored at
all times. Do not wander around the room,
distract other students, startle other students
or interfere with the laboratory experiments
of others.
Goggles on at all times
Any time chemicals, heat, or glassware are used,
students will wear safety goggles. NO
EXCEPTIONS TO THIS RULE
Ask for help
If you do not understand
how to use a piece of
equipment, ASK THE
TEACHER FOR HELP!
If there is a problem…
YELL FOR HELP
If you or your lab partner is hurt,
immediately (and loudly) yell out the
teacher's name to get the teacher's
attention. Do not panic.
USE the eye wash
If a chemical should splash in your eye(s) or on
your skin, immediately flush with running
water for at least 20 minutes. Immediately
(and loudly) yell out the teacher's name to get
the teacher's attention.
Notify of dangerous hazards
Be alert and proceed
with caution at all
times in the
laboratory. Notify
the teacher
immediately of any
unsafe conditions
you observe
Report accidents or injuries
Report any accident (spill, breakage, etc.) or
injury (cut, burn, etc.) to the teacher
immediately, no matter how trivial it
seems. Do not panic.
T-1: Fire Extinguiser is by the door, first
aid is by the whiteboard
Know what to do in a drill
Know what to do if
there is a fire drill
during a
laboratory period;
containers must
be closed, and any
electrical
equipment turned
off
If there is a problem…
1) What should you do if someone is injured?
2) Where is the first aid located?
3) What do you do if something gets in your
eyes?
FOR GLASSWARE
Use clean, unbroken glassware
Examine glassware before each use. Never use
chipped, cracked, or dirty glassware.
Don’t touch broken glass
Never handle broken
glass with your bare
hands. Tell the teacher
immediately, the
teacher will clean it up.
Nothing hot in the sink
Do not immerse hot glassware in cold
water. The glassware may shatter.
Be careful with the hot plate
Do not operate a hot plate
by yourself. Take care that
hair, clothing, and hands
are a safe distance from
the hot plate at all
times. Use of hot plate is
only allowed in the
presence of the teacher.
Use
tongs for
hot items
Heated glassware remain very hot for a long
time. They should be set aside in a designated
place to cool, and picked up with caution. Use
tongs or heat protective gloves if necessary.
Don’t watch a boiling test tube
Never look into a container that is being heated.
Don’t touch hot plates or test tubes
Do not place hot
apparatus directly
on the laboratory
desk. Always use
an insulated
pad. Allow plenty
of time for hot
apparatus to cool
before touching it.
Always use
your brain
ALWAYS think
before you do
something!!!!
For glassware
1) What things can happen to glassware that
you should be aware of?
2) How should you touch glassware that has
been on the hot plate?
3) Why shouldn’t you look at a boiling test
tube?
CLEANING UP
Wash your hands
Keep hands away from face, eyes, mouth,
and body while using chemicals or lab
equipment. Wash your hands with
soap and water after performing all
experiments.
Dispose of chemicals
• Dispose of chemicals in waste containers, not
down the sink
Cleaning
1) What do you do with the chemicals that you
have finished with?
2) What should you do before you leave the lab?
Get dressed
• Gloves
• Aprons