Download What Are Enzymes?

Energy and Metabolism
Vocabulary
1/14 – Enzymes
1/15 – metabolism
1/16 – activation energy
I can….
1/14 – Name the suffix
enzymes USUALLY
end.
1/15 – Define an enzyme.
1/16 – Describe how
enzymes may reduce
activation energy.
Hang With Me Today!!!


Bond energy, activation energy,
parts of reaction, and types of
reaction.
HOW ALL THIS IS CONNECTED
TO ENZYMES?????
The Energy of Life

Metabolism – digestion to make energy
and life processes!!!!
 ITS HOW YOU DIGEST FOOD AND
BUILD UP BACK INTO WHAT YOU
NEED!!!

INVOLVES CHEMICAL REACTIONS
Examples of Reactions
Photosynthesis, ATP synthesis, Cellular
respiration, Protein synthesis, making lipids, and
breaking down starch, Breaking down hydroden
perioxide into water,
Breaking down of lipids, proteins, and
carbohydrates, alcohol, etc
Why would someone metabolism
be better?
How do you digest alcohol?
Where does it go?
What causes alcoholic bingeing to be
dangerous?
Alcohol Metabolism

Since alcohol is not stored or used, it is
metabolized before any nutrition. Long term
drinking leads to malnutrition. If on diet,
causes you to retain your weight, because
your body does not digest fat. Alcohol first.
A Toast to Alcohol Dehydrogenase
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Metabolic processes break down organic
molecules such as ethanol and other toxins –
binge drinking is currently the most serious
drug problem on college campuses.
Different people – sex and race produce
different amounts of dehydrogenase. If no
dehydrogenase, then alcohol stays in your
bloodstream.
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Alcohol dehydrogenase (ADH) converts
ethanol to toxic acetaldehyde(POISON),
which is then converted to acetate by ALDH.
This leads to alcohol poisoning- bingeing!!!
What do you think of when you
think of a chemical reaction?
Name some chemical reactions.
Do you think photosynthesis and
cellular respiration are chemical
reactions?
Can You Think of Any Reactions
in Your Body?
Where to you think oxygen and carbon
dioxide come from?
Chemical Reactions
Change substances into different
substances by breaking and
forming chemical bonds.
DOES THIS OCCUR WITH
DIGESTION?
Parts of an Equation
All chemical reactions…
have two parts:
1.
2.

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Reactants = the substances you start with
Products = the substances you end up with
The reactants will turn into the
products.
Reactants  Products
A Chemical Reaction
Catabolic Reaction

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Digestion or breaking apart large molecules to
use for energy or rebuilding
Protein – amino acid
Carbohydrate - monosaccharide
Anabolic Reaction

Building of polymers to reconstruct the cell.

Amino acids – proteins
Lipids - cholesterol

Bond Energy

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BOND ENERGY :Amount of energy needed
to break the bonds between molecules.
Energy is needed to break bonds. The stronger
the bond the more energy needed. The
amount of energy is different for all bonds.
Energy is released when bonds are formed
like with H and O to make water.
Gummi Bear Video

Read the internet article!!!
Activation Energy
Energy needed to get the reaction
started.
Photosynthesis: sunlight
Fuel: match
Activation Energy

Energy needed to get the reaction started.
Some reaction takes more energy than others.
Usually this is increasing the temperature but
organisms cannot change the temperature so
something else has to help decrease the
amount of energy needed. We cannot use all
our energy for reactions like photosynthesis
and respiration.
Bozeman - activation energy

Snowman – video over activation energy
Exothermic and Endothermic
Reactions

A reaction in which heat or more energy is
produced is given out is exothermic.

A reaction in which heat is taken in or more
energy is used is endothermic.
ENERGY AND CHEMICAL
REACTIONS
Exothermic reactions
 These reactions give out heat energy.
 Combustion is an exothermic reaction.
Exothermic reactions

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Chemical reaction where more energy is
released than it absorbs
Difference in energy between reactant and
products.
Usually heat or light.
EX: Cellular respiration
Energy Level Diagrams
These are drawn as graphs.
They are used to show exothermic and
endothermic reactions.
The x axis shows time, the y axis shows energy.
Energy
Time
Exothermic Reactions
An exothermic energy diagram looks like this.
reactants
Energy
products
Time
}
Energy released
Exothermic Reactions
Combustion and respiration are exothermic reactions.
e.g. burning methane (natural gas).
CH4 + 2O2 
2H2O
+ CO2
CH4 + 2O2
Energy
2H2O + CO2
Time
}
Energy released
Exothermic Reaction
ENERGY AND CHEMICAL
REACTIONS
Endothermic reactions
 These reactions take in heat energy from their
surroundings.
 These cause temperatures to fall. They get
cold!!!
Endothermic reactions

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
Chemical reaction where more energy is
absorbed than released. IT IS A NET
THING!!!
Energy must be absorbed to make up
difference between reactants and products
EX: photosynthesis Traps energy in bonds of
glucose
Endothermic Reactions
Examples are photosynthesis and most electrolysis reactions.
The energy level diagrams look like this.
products
Energy
reactants
Time
}
Energy needed
to make the
reaction work.
Endothermic Reaction
When trying to classify a process as exothermic or endothermic, watch how the
temperature of the surroundings changes. An exothermic process releases heat, and
causes the temperature of the immediate surroundings to rise. An endothermic process
absorbs heat and cools the surroundings. Can you think of a way to test the classification
of each of these processes?
Exothermic processes - gives off energy
Endothermic processes- takes in
energy
melting ice cubes
conversion of frost to water vapor
evaporation of water
making ice cubes
formation of snow in clouds
condensation of rain from water vapor
a candle flame
mixing sodium sulfite and bleach
baking bread
rusting iron
cooking an egg
burning sugar
producing sugar by photosynthesis
forming ion pairs
separating ion pairs
Combining atoms to make gas
splitting a gas molecule apart
mixing water and strong acids
mixing water and ammonium nitrate
mixing water with an anhydrous salt
crystallizing liquid salts
in chemical handwarmers)
melting solid salts
nuclear fission reaction of barium hydroxide octahydrate crystals with dry ammonium ch
Explain why this is a graph of
photosynthesis.
Where is the
activation
Energy
On the
Graph?
Increase of Temperature How to
get Activation energy

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Can organisms have a great increase in
temperature?
Need other ways to get increase or to decrease
the amount of activation energy needed
This is where catalysts come into play.
CATALYST

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A substance that decreases the activation
energy needed to start a reaction. Usually
temperature increase but organisms cannot
have a great increase in temperature or die
Increases the rate of reaction or speed of
reactions.
They break the bonds between the reactants to
speed up the reaction.
Enzymes
41
ENZYMES
*A type of protein that acts as a catalyst which
lowers activation energy needed to start a
reaction.
*They speed up reactions by weaken bonds.
*Always in in -ase
© 2007 Paul Billiet ODWS
What Are Enzymes?
Most enzymes are
Proteins (tertiary
and quaternary
structures)
 Act as Catalyst to
accelerates a
reaction
 Not permanently
changed in the
process

43
How do enzymes Work?
Enzymes work
by weakening
bonds which
lowers
activation
energy
44
Enzyme structure

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Enzymes are
proteins
They have a
globular shape
A complex 3-D
structure
.
© 2007 Paul Billiet ODWS
Enzymes
Are specific for
what they will
catalyze
 Are Reusable
 End in –ase
-Sucrase
-Lactase
-Maltase
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46
The substrate
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The substrate of an enzyme are the reactants
that are acted on by the enzyme.
Enzymes are specific to their substrates
The specificity is determined by the active
site
ENZYMES ARE SHAPED TO FIT ONLY
THEIR SUBTRATE BECAUSE THEIR
ACTIVE SITE IS SHAPED TO FIT
ONLY ONE SUBSTRATE!!!!
© 2007 Paul Billiet ODWS
The active site
PLACE WHERE
SUBSTRATE FITS!!
ONLY THE ONE
SUBTRATE WILL
FIT!!!
© H.PELLETIER, M.R.SAWAYA
ProNuC Database
© 2007 Paul Billiet ODWS
Enzyme Structure
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It fits like a lock and key with its subtrate.
Will not fit any other substance.
How Works
1. Enzyme brings molecules close together.
2. By bonding they have weaken the bonds of
the subtrate so they reaction can occur
quicker.
An enzyme controlled pathway
© 2007 Paul Billiet ODWS
The Lock and Key Hypothesis
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Fit between the substrate and the active site of the
enzyme is exact
Like a key fits into a lock very precisely
The key is analogous to the enzyme and the substrate
analogous to the lock.
Temporary structure called the enzyme-substrate
complex formed
© 2007 Paul Billiet ODWS
The Lock and Key Hypothesis
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This explains enzyme specificity
This explains the loss of activity when
enzymes denature
© 2007 Paul Billiet ODWS
Different Types of Enzymes
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Metabolic or digestive enzymes to digst food
Detergent enzymes
There are over 500 enzymes in just one cell!!
Needed to speed up reactions or wold be too
slow!!!
Enzymes
Without Enzyme
With Enzyme
Free
Energy
Free energy of activation
Reactants
Products
Progress of the reaction
55
57
Enzyme-Substrate
Complex
The substance (reactant) an enzyme
acts on is the substrate
Substrate
Joins
Enzyme
58
Active Site

A restricted region of an
enzyme molecule which binds
to the substrate.
Active
Site
Substrate
Enzyme
59
Induced Fit
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A change in
the shape of
an enzyme’s
active site
Induced by
the substrate
60
Induced Fit
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A change in the configuration
of an enzyme’s active site (H+
and ionic bonds are involved).
Induced by the substrate.
Active Site
substrate
Enzyme
induced fit
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Digestive enzymes are secreted by the body to
digest the food eaten.
There are three categories of digestive
enzymes:
• Amylases (found in saliva, the pancreas, and
intestinal juices) break down carbohydrates; •
Proteases (found in the stomach, pancreatic,
and intestinal juices) help digest protein; •
Lipases (pancreatic juices, and in food fats) aid
in fat digestion. •
•Amylase enzymes are found in the saliva and in the
juices of the pancreas and intestinal tract and help the
digestive process by breaking down carbohydrates.
There are different kinds of amylase. For example, the
enzyme sucrase breaks down the sugar sucrose found
in cane and beet sugar. The enzyme lactase breaks
down the lactose sugar in milk. The enzyme maltase
breaks down the malt sugar maltose.
•Protease enzymes are found in the juices of the
pancreas, the stomach and the intestinal tract and help
with the breakdown and the digestion of proteins.
•Lipase enzymes are found in the juices of the stomach
and pancreas and help to break down fats.
What Affects Enzyme
Activity?

Three factors:
1.Environmental Conditions
2.Enzyme Inhibitors
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Denaturing of Enzymes

Denaturing: enzyme structure can be
destroyed by many different factors.
1.
Environmental and inhibitors
1. Environmental Conditions
A. Extreme Temperature are the
most dangerous high temps may
denature (unfold) the enzyme.
B. pH (most like 6 - 8 pH near
neutral)
C. Ionic concentration (salt ions)
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The effect of temperature
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For most enzymes the optimum temperature is about
30°C
Many are a lot lower,
cold water fish will die at 30°C because their
enzymes denature
A few bacteria have enzymes that can withstand very
high temperatures up to 100°C
Most enzymes however are fully denatured at 70°C
© 2007 Paul Billiet ODWS
The effect of temperature
Q10
Enzyme
activity
0
© 2007 Paul Billiet ODWS
10
20
30
40
Temperature / °C
Denaturation
50
Increase of Temperature
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Can organisms have a great increase in
temperature?
Need other ways to get increase or to decrease
the amount of activation energy needed
This is where catalysts come into play.
The effect of pH
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Extreme pH levels will produce denaturation
The structure of the enzyme is changed
The active site is distorted and the substrate
molecules will no longer fit in it
At pH values slightly different from the enzyme’s
optimum value, small changes in the charges of the
enzyme and it’s substrate molecules will occur
This change in ionisation will affect the binding of
the substrate with the active site.
© 2007 Paul Billiet ODWS
Enzymes work in different pH

All enzymes can work in different conditions
Intestines would have a lower pH than mouth.
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Look at website for examples!!!!!!
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The effect of pH
Optimum pH values
Enzyme
activity
Trypsin
Pepsin
1
© 2007 Paul Billiet ODWS
3
5
7
pH
9
11
Inhibitors
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Inhibitors are chemicals that reduce the rate of
enzymic reactions.
The are usually specific and they work at low
concentrations.
They block the enzyme but they do not
usually destroy it.
Many drugs and poisons are inhibitors of
enzymes in the nervous system.
© 2007 Paul Billiet ODWS
Two examples of Enzyme
Inhibitors
a. Competitive inhibitors: are
chemicals that resemble an
enzyme’s normal substrate and
compete with it for the active
site.
Substrate
Competitive inhibitor
Enzyme
76
Inhibitors
b. Noncompetitive inhibitors:
Inhibitors that do not enter the active
site, but bind to another part of the
enzyme causing the enzyme to change its
shape, which in turn
alters the
active site.
Substrate
active site
altered
Enzyme
Noncompetitive
Inhibitor
77
Enzymes
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Substrate, active site, factors that affect
enzymes!!
Uses for enzymes
Purpose – How do they speed up reactions
Examples
Metabolic Enzymes
Metabolic enzymes run all the body organs and
systems by performing various chemical
reactions within the body cells. Catalase, which
breaks down hydrogen peroxide, a metabolic
waste product, liberating the oxygen for use in the
body..

Place cracker in mouth!! What happens!!
WHY?????
Would this happen with a piece of meat?

Why or why not?

http://highered.mcgraw-hill.com/sites/0072495855/student_
view0/chapter2/animation__how_enzymes_work.html

1.
Enzymes have five important properties that you should know:
They are always proteins.
2. They are specific in their action. Each enzyme controls one
particular reaction, or type of reaction. Thus sucrase degrades
sucrose and only sucrose (table sugar).
3. They are not altered by the reaction. This means that an enzyme
can be used repeatedly. It also means that enzymes appear neither
in the reactants nor in the products of a chemical equation.
4. They are destroyed by heat. This is because enzymes are proteins,
and all proteins are destroyed by heat. Destruction of protein by
heat (or under any extreme conditions of pH or salt concentration)
is called denaturation.
5. They are sensitive to pH. The term pH refers to the degree of
acidity and alkalinity of a solution. Most intracellular enzymes work
best in neutral conditions, i.e. conditions that are neither acidic nor
alkaline.

Hydrogen peroxide (H2O2) is a poisonous byproduct of metabolism
that can damage cells if it is not removed. Catalase is an enzyme that
speeds up the breakdown of hydrogen peroxide into water (H2O) and
oxygen gas (O2).

2H2O2--------catalase--------------> 2H2O + O2

REMEMBER: A CATALYST is a substance that lowers the activation
energy required for a chemical reaction, and therefore increases the rate of
the reaction without being used up in the process. CATALASE is an
enzyme, a biological (organic) catalyst. Hydrogen peroxide is the
substrate for catalase.
CATALASE!!!
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Hydrogen peroxide (H2O2) is something you can buy at the drug store. What you
are buying is a 3-percent solution, meaning the bottle contains 97-percent water
and 3-percent hydrogen peroxide. Most people use it as an antiseptic. It turns out
that it is not very good as an antiseptic, but it is not bad for washing cuts and
scrapes and the foaming looks cool.
The reason why it foams is because blood and cells contain an enzyme called
catalase. Since a cut or scrape contains both blood and damaged cells, there is lots
of catalase floating around.
When the catalase comes in contact with hydrogen peroxide, it turns the hydrogen
peroxide (H2O2) into water (H2O) and oxygen gas (O2).
Catalase does this extremely efficiently -- up to 200,000 reactions per second.
The bubbles you see in the foam are pure oxygen bubbles being created by
the catalase. Try putting a little hydrogen peroxide on a cut potato and it will
do the same thing for the same reason -- catalase in the damaged potato cells
reacts with the hydrogen peroxide.
Hydrogen peroxide does not foam in the bottle or on your skin because there is no
catalase to help the reaction to occur. Hydrogen peroxide is stable at room
temperature.
Hydrogen peroxide is not only found at the drug store…
it is also produced in the human body by cells of the
immune system, for example. These cells make H2O2
to combat infection during the inflammatory process.
BUT too much Hydrogen peroxide kills cells
by destroying their cell membranes. In other words,
H2O2 can, and does cause harm to the human body.
The biochemistry of hydrogen peroxide is complex
and widely researched. It is an essential molecule for
our survival. However, our bodies are pretty smart; they
use enzymes to keep levels under control.