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First Five
Turn in the Winter Break HW
Grab a packet from the
podium
Spend the next 15 minutes
reading and working on the
packet
Intro to
Enzymes
Today’s Objectives
 B3-1 Define enzymes as proteins that function
as biological catalysts.
 B4.3-12 State where, in the alimentary canal,
amylase, protease and lipase enzymes are
secreted.
 B4.3-13 State the functions of a typical amylase,
a protease and a lipase, listing the substrate and
end-products.
Turn and Talk
What is a “catalyst”?
What are Enzymes?
Biological catalysts that increase
reactions rates
Catalysts: substances that speed
up reactions w/o being consumed
Biological? Because they are
proteins; NOT because they are
alive (they aren’t!)
Enzyme-Catalyzed Reactions
Hydrogen peroxide (H2O2) is
broken down into water and
oxygen gas
Write the word equation for
this reaction.
Hydrogen peroxide  Water + Oxygen
Enzyme-Catalyzed Reactions
Hydrogen peroxide (H2O2) is
broken down into water and
oxygen gas
Hydrogen peroxide  Water + Oxygen
Write the balanced symbol
equation for this reaction.
Enzyme-Catalyzed Reactions
This reaction is catalyzed by the
enzyme catalase.
How do we show this in the equation?
Catalase
Hydrogen peroxide --------------> Water + Oxygen
Enzyme-Catalyzed Reactions
In an enzyme reaction, we use the following terms:
Substrate: substance(s) changed by the
enzyme reaction (the reactants)
Product: substance(s) produced by the
enzyme reaction
Catalase
Hydrogen peroxide --------------> Water + Oxygen
Reactant
Products
Identify the substrate and the products for the
reaction above.
More Practice
A.Write the word equation for the examples below.
B. Then, identify the enzyme, substrate(s), and
product(s)
I)Acetylcholinesterase breaks down acetylcholine into
acetyl and choline.
Enzyme: _________ Substrate(s): _________ Product(s): ________
II) A disaccharide can be broken down into glucose
and fructose by lysozyme
Enzyme: _________ Substrate(s): _________ Product(s): ________
How Enzymes Work: Mode of Action
With a partner, place the pictures in order (first to
forth).
Then, match the pink terms to the appropriate
places on the diagram.
Once done, answer these 3 questions in your
notebook.
1. What happens to the substrate during the
reaction?
2. What happens to the enzyme? The active site?
3. What happens during the 2nd and 3rd step in the
diagram?
Mode of Action
Discussion Time
Why are enzymes so
important for life?
Protease
Proteases break down
proteins.
Baby food:
As babies can’t digest solid food, using protease enzymes makes it easier for a baby’s
digestive system to cope with it.
Proteases are used to produce baby food from cow’s milk. The proteases break down milk
proteins into amino acids, diminishing the risk of babies developing milk allergies.
Particular proteases are also used for the production of hypoallergenic food . These
proteases break down specific allergenic proteins that can cause allergic reactions.
What else?
•Animals produce digestive enzymes that break down proteins,
such as trypsin and pepsin.
•Some plants, such as pineapple, have a high protease content.
The main enzyme of pineapple is called papain.
•Many foodstuffs (meat, cheese, fish) also contain proteases or
activate them during the process of maturing. The "hanging" of
meat activates digestive enzymes that tenderise the meat.
Carbohydrase: Lactase
Carbohydrases are a group of enzymes which digest carbohydrates
into the simpler sugars they are made from.
Lactase is a carbohydrase enzyme which helps to break down lactose (a sugar
found in milk) into simple sugars.
Lactase is secreted in the intestine to break down the lactose in milk into sugars
which can be absorbed. If the enzyme isn’t present, the lactose cannot be
converted into sugars such as glucose.
A lack of this enzyme causes lactose intolerance. The lactose can’t be broken
down and acts as a great food source for gut bacteria.
The amount of lactase mammals produce
tends to decrease with maturity however
humans have evolved to keep producing the
enzyme into adulthood due to the amount of
milk consumed.
Carbohydrase
Carbohydrases are a group of enzymes which digest carbohydrates into the simpler
sugars they are made from.
Used to convert starch syrup, which is relatively cheap, into sugar (glucose)
syrup, which is more valuable - for example, as an ingredient in sports drinks.
We can get starch from plants eg: corn which is very cheap. Using
carbohydrases to convert this to sugar means it is a cheap source of sweetness
for food manufacturers
Carbohydrases are also
used in making fuel from
plants (ethanol).
Biological
detergents
Used to remove stains such as blood, grass, sweat and food from clothes.
Biological washing powders contain proteases and lipases. Proteases break down
proteins and lipases break down fats in the stains into smaller water soluble
substances.
They still work at the lower
temperatures enzymes work at, which
makes washing more environmentally
friendly.
Isomerase
Isomerase enzyme is used to convert glucose syrup into
fructose syrup. it does this by rearranging the atoms in the
glucose molecules.
Glucose and fructose contain the
same amount of energy however
fructose is a sugar which is sweeter
than glucose.
Using fructose in foods means that
less is needed which is why it is
used in slimming foods. Food tastes
sweet but contains fewer calories!
The enzyme isomerase is normally
"immobilised" when used, i.e., it is fixed to
a transporter and is not transferred to the
product or ingredient on which it is used.
Enzymes for Digestion
For dinner you eat a bean and cheese
burrito. Now what?
Your teeth chewed it to smaller pieces,
but then you swallowed. In order to get
energy from this, your digestive system
needs to break it down even more.
This is done by chemical digestion
Chemical Digestion
Definition: the breakdown of
large molecules of food into
smaller ones, done by enzymes
Digestive Enzymes Video
Fill out table based on: https://www.youtube.com/watch?v=vTQybDgweiE
BEFORE: Use the shaded card cut-outs to fill in
the first two columns of the table.
DURING: Use the non-shaded cards to fill out
the third and fourth columns of the table, based
on the info presented.
AFTER: 1) Write the word equation for the
enzyme-catalyzed reaction. 2) Copy the
completed table into your notebook
Digestive Enzymes Video
Fill out table based on: https://www.youtube.com/watch?v=vTQybDgweiE
Class review of table
Exit Ticket
Silently answer the following
question in your notebook. In 5
minutes, we will trade with
partners and peer grade.
Why are enzymes
referred to as
“biological catalysts”?