Welcome Back!
1. What do you think Isaac Asimov meant
when he wrote:
"When people thought the earth was flat,
they were wrong. When people thought
the earth was spherical, they were wrong.
But if you think that thinking the earth is
spherical is just as wrong as thinking the
earth is flat, then your view is wronger
than both of them put together."
Homework
None… yet!
Make up any missing work.
Objectives
Know the main six elements that make
up living things, and which one is most
important
Elements
 The main six elements that make up living
things, in order of importance/prevalence:
 1. CARBON
 2. Hydrogen
 3. Oxygen
 4. Nitrogen
 5. Phosphorus
 6. Sulfur
Today’s Activities
 You choose:
Like working with models? I challenge you to
make chemical models of the four
macromolecules.
Like games? Or philosophy? Want to get better
at winning arguments? Play a matching game
with logical fallacies.
If you missed the protein synthesis quiz, you will
take it now.
Coming Up
 Mini-unit on enzymes
 Midterm
 Food for thought:
"When people thought the earth was flat, they
were wrong. When people thought the earth was
spherical, they were wrong. But if you think that
thinking the earth is spherical is just as wrong as
thinking the earth is flat, then your view is wronger
than both of them put together." -Isaac Asimov
Enzymes
What do you think Isaac Asimov meant
when he wrote:
"When people thought the earth was flat, they
were wrong. When people thought the earth
was spherical, they were wrong. But if you
think that thinking the earth is spherical is
just as wrong as thinking the earth is flat,
then your view is wronger than both of them
put together.”
1.
2. (Sticker) What gives different proteins
different behaviors and functions?
Homework
 None tonight
 Start studying for the midterm!
Not much nature of science content, mostly just
the vocabulary (theory, law, fact, observation,
hypothesis)
Cell biology, membranes & transport, energy &
metabolism, DNA, protein synthesis, enzymes,
chemistry of macromolecules (included in all the
other units)
Objectives
Be able to explain what a catalyst is.
Know the term for catalysts made by living
things, and know what those catalysts are
made of.
Explain “induced fit” and specificity
Enzymes
Common misconceptions: When you’re
sick, sometimes your body temperature
rises. What’s giving you the fever? The
bacteria or virus, or are you giving it to
yourself?
Why is fever induced?
Enzymes
One of the most important protein
groups to understand are the enzymatic
proteins - enzymes.
Nearly everything that a cell does requires
an enzyme to happen.
Enzymes are important to understanding
how an organism maintains homeostasis a stable internal environment.
Chemical Reactions
 Cells must carry out millions of chemical
reactions to survive, but they have a problem:
most of those reactions won’t happen on their
own.
These reactions include DNA replication,
photosynthesis, cellular respiration, active
transport, breaking down food molecules…
 First, in a reaction, what is a “reactant?”
What is a “product?”
Chemical Reactions
A chemical reaction is turning reactant/s
into product/s.
Activation energy is the amount of
energy that the reactants have to have
in order for the reaction to start
happening.
QuickTime™ and a
decompressor
are needed to see this picture.
Chemical Reactions
If the activation energy of the reaction is
higher than the energy that the
reactants have, then the reaction will
happen very slowly, or not at all.
Most cellular reactions are in this
situation. They need help.
QuickTime™ and a
decompressor
are needed to see this picture.
Catalysis
A catalyst is a chemical that makes a
reaction go faster, without being
damaged or used up.
(We say it
“catalyzes” the reaction.)
•It does this by messing
with activation energy.
How would you change
activation energy, if you
wanted to make a
reaction easier?
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decompressor
are needed to see this picture.
Catalysts
Catalysts work
QuickTime™ and a
decompressor
are needed to see this picture.
by lowering
activation
energy.
Gas in a car
analogy
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decompressor
are needed to see this picture.
Catalysts
QuickTime™ and a
decompressor
are needed to see this picture.
There are lots of different kinds of
catalysts. The main kind of catalyst
used in living things are enzymes.
Enzymes are catalysts that are proteins.
Enzymes
 Checkpoint:
What is activation energy?
Does a catalyst make a reaction go faster or
slower?
What does a catalyst do to a reaction’s activation
energy?
After the reaction is done, is the catalyst the same
as it was before?
Enzymes are catalysts that are made of what?
Enzymes
(In these kinds of reactions, we call the
reactant the substrate.)
The active site is where the reactants
bind to the enzyme.
QuickTime™ and a
decompressor
are needed to see this picture.
Enzymes
Enzymes are highly specific. Each
enzyme with its unique shape will only
fit a certain substrate, so it will only
catalyze a certain reaction.
•Remember, enzymes are
proteins. Different
proteins having different
shapes mean that they
also have different ___?
QuickTime™ and a
decompressor
are needed to see this picture.
Enzymes
Enzymes are somewhat flexible,
though. They bend a bit to
accommodate the substrate. Copy this
diagram of the induced fit model and
label the enzyme-substrate complex:
QuickTime™ and a
decompressor
are needed to see this picture.
Enzymes
http://www.youtube.com/watch?v=cbZs
XjgPDLQ
http://highered.mcgrawhill.com/sites/0072495855/student_view
0/chapter2/animation__how_enzymes_
work.html
Enzymes
 Who can explain back to me how an enzyme
works?
 Example: http://highered.mcgraw-
hill.com/sites/0072507470/student_view0/cha
pter25/animation__enzyme_action_and_the_
hydrolysis_of_sucrose.html
Enzymes
 How well an enzyme does its job, meaning
how quickly a reaction proceeds, is not
always the same, though.
 We’ll use play-doh and a computer model to
figure out how these things affect enzyme
activity: increasing or decreasing
temperature, pH change, enzyme
concentration, substrate concentration
 http://www.kscience.co.uk/animations/model.swf
Enzymes
 Quiz+ due Monday.
 Grab a laptop, navigate to
harwichbio.wikispaces.com and continue with
the enzyme packet!
When you finish a “KEY CONCEPT” question,
check your answer with me before continuing.
 You must finish sections I-III. If you don’t finish them in
class, they are assigned as homework.
Key Concepts Review
 Catalysts are molecules that help chemical
reactions go faster, without being changed
themselves. Some reactions could never
happen at all unless an enzyme helped.
 Catalysts that are proteins and work in living
things are called enzymes.
Enzymes make reactions happen in cells.
Enzymes are very specific, they have an active
site that will usually only squish to fit one particular
chemical. That the enzyme squishes a little to fit a
chemical to its active site is called “induced fit.”
The reactant in the reaction that the enzyme is
helping is called the substrate. When the enzyme
is bonded to the substrate it’s helping, we call
them an enzyme-substrate complex.
Cells can’t live without enzymes.
Enzyme Lab
• The three greatest dangers: Hydrochloric acid
(HCl), sodium hydroxide (NaOH), and the
boiling bath.
– HCl and NaOH are corrosive. They will damage
skin and eyes, potentially causing blindness if
correct action isn’t taken. They are toxic if
swallowed.
– Liquids may be boiling after being in the boiling
bath even if they don’t look like it. Treat them as
though they’re liable to “burst.”
• ONLY do what the lab procedure instructions,
and follow all safety protocols:
Lab Safety
• 1. All belongings - coats, backpacks, purses will be put on the window tables. All chairs
pushed in.
• 2. Speak in low tones, so that if there is an
emergency, everyone can hear me call out
instructions immediately.
• 3. If I speak to you, immediately stop talking
and pay attention, in case I’m there with a
safety instruction.
– If I say No or Stop, you STOP whatever you’re
doing. Zero tolerance for failure to follow
instructions.
– Horseplay, no matter how innocent, is an
immediate ban from lab.
Lab Safety
• 4. Read the directions to each part as a
group before doing that section, and talk it
over together so you all understand what to
do.
– Before each section, decide on a role for each
group member, and ready only the materials you
will need for that section.
• 5. If you break glass, place the broken item in
the white bin. Call me to consult on clean-up.
• 6. Be sure that the lid is tightly screwed onto
the bottles.
– Check for this when you first get them, and recheck after you use them.
Lab Safety
• 7. WEAR GOGGLES AT ALL TIMES.
• 8. If you spill HCl or NaOH on your
skin, flush with water.
– If you were foolish enough to not wear
goggles and you get any in your eyes,
immediately start flushing them in the eye
fountain and don’t stop until I, the nurse, or
the paramedics say you can stop.
Lab Safety
• 9. Wash your materials every time you’re
done using it for that part of the experiment.
– Slowly pour used test tube contents down sink
while running water. Pour only one test tube in the
sink at a time!
– Do NOT MIX ANYTHING unless the lab tells you
to. Pay attention to bottle labels.
• 10. Never touch the hotplate or a test tube
that’s been in the boiling water. Use a test
tube holder.
– Don’t touch a hot and cold test tube together, they
may shatter.
– Point test tubes that have been heated away from
faces.
Lab Safety
• 11. Nobody in your group leaves class
until your materials are clean and
returned to the counter. No passes will
be given. When I say “stop and clean
up,” stop and clean up!
– The last thing you do before leaving the
room is to wash your hands.
Lab
• Cross out part B, we’re going to skip it.
• Everyone do Part A first.
• Again: read through the procedure for each
part before you do it. Decide on who has
what role. Only then do you do it.
– If you are not sure that you understand what to do,
or what a question is asking for, ask me for help!
Notes on Things that have
been Messing People Up
• Only use the plastic dropper for the liver
enzyme, and only use the graduated cylinder
for the hydrogen peroxide.
• Don’t use a plugged up sink!
• The little arrows in the data table correspond
to questions in the procedure that you must
answer.
• Read the instructions first and narrate what
you’re going to do before you do it.
(Don’t use clogged sinks!)
SET UP
• 1. Put all materials except lab packet over by
the window. Push in all chairs you’re not
sitting in.
• 2. Put on goggles.
• 3. Get a lab tray.
• 4. Read through the procedure for whatever
part you’re on with your team. Narrate what
you’re going to do before you do it.
– 5. Be sure you’re filling in the data table.
Reaction rates go in one column, question
answers go by their arrows.
– 6. Discuss answers to questions together as you
go.
CLEANUP ORDER
• 1. Pour test tube contents down sink while
running the water.
– Pour only ONE tube in a sink at a time.
• 2. Rinse used glassware with water.
– Do not throw away your unused liver enzyme,
HCl, NaOH, or hydrogen peroxide!
• 3. Put your clean lab station back on the
counter.
• 4. Return goggles.
• 5. Wash hands. If our sink is crowded with
clean-up, you can use a bathroom sink.
• I. Enzyme
– A. Definition
•
•
•
•
1.
2.
3.
4.
Biological catalyst
Made of protein
Interacts with substrate = reactant
Not used up in reaction
– B. Function
• 1. Lowers activation energy
– a) Activation energy = energy needed for reaction to happen
• 2. Increases reaction rate
– C. Specificity
• 1. Highly specific, often fits only one substrate
• 2. Works best at certain temp, pH
– a) Temp too high changes shape, which deactivates it
– b) Otherwise, higher temperatures = faster reaction
 1.

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
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

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
http://www.nelsonthornes.com/secondary/science/scinet/scinet/reaction/cont
ent.htm
2. http://misterguch.brinkster.net/6typesofchemicalrxn.html
3.
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookEnzym.html
4. http://www.biotopics.co.uk/other/enzyme.html
5. http://www.tvdsb.on.ca/westmin/science/sbi3a1/digest/enzymes.htm
6. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enzymes.html
7. http://student.ccbcmd.edu/biotutorials/proteins/enzyme.html
8. http://www.youtube.com/watch?v=cbZsXjgPDLQ
9. http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_enzym
es_work.html
10. http://www.worthington-biochem.com/introBiochem/introEnzymes.html
11. http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__enzyme_ac
tion_and_the_hydrolysis_of_sucrose.html
12.
http://programs.northlandcollege.edu/biology/Biology1111/animations/enzym
e.swf
13. http://www.biologyinmotion.com/minilec/wrench.html