Download Text 5- Pre and Post Reading Activities Enzymes

Grade 10 Science Related Reading/Chemistry
Chemistry Gr10
Name:____________________
Class:____________________
Date:____________________
Chlorinated
hydrocarbons
Enzymes make
the world go
and “round”
their uses
Task 1 – Pre-Reading Activity
Watch the animation given in the following link and answer the questions that follow:
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html
1. Enzymes are
a. Carbohydrates
b. Fats
c. Proteins
d. Nucleic acids
2. Which one of the following attaches to the enzyme?
a.
Water
b. Substrate
c.
another enzyme
d. product
3.
An enzyme can only bind to one reactant at a time.
a. True
b. False
4.
An enzyme speeds up a chemical reaction in a cell , but can be used only once.
a. True
b. False
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Task 2 – Reading Activity
Enzymes are compounds that assist chemical reactions by increasing the rate at which they
occur. For example, the food that you eat is broken down by digestive enzymes into tiny
pieces that are small enough to travel through your blood stream and enter cells. Enzymes are
proteins that are found in all living organisms. Without enzymes, most chemicals reactions
within cells would occur so slowly that cells would not be able to work properly. Enzymes
function as catalysts. Catalysts accelerate the rate of a chemical reaction without being
destroyed or changed. They can be reused for the same chemical reaction over and over, just
like a key can be reused to open a door many times. Enzymes are generally named after the
substrate affected, and their names usually end in -ase. For example, enzymes that break
down proteins are called proteases. While lipases break down lipids, carbohydrases break
down carbohydrates.
The compounds that enzymes act upon are known as substrates. The site at which the
enzyme attaches to substrate is called the active site. An enzyme can lower the energy
needed for a reaction to occur, thus making this reaction faster. The energy required for a
chemical reaction to occur is known as the activation energy. Once the reaction between an
enzyme and a substrate is complete, the substrate is changed to a product while the enzyme
remains unchanged.
Since the 1950s, enzyme technology has really taken off. It is the basis of the new industry
called biotechnology. There are great benefits in using enzymes as catalysts to make
products. They can be some 10,000 times more efficient than ordinary inorganic catalysts
used in industry. One enzyme molecule can catalyse 10 million reactions in a single second!
They also work at relatively low temperatures (typically, about 40 °C), saving energy and
therefore saving money.
Some of the Industrial applications of enzymes are as follows:
Yoghurt
Milk contains a sugar called lactose. Natural bacteria in the
milk turn this into lactic acid . It is the first step in making
cheese or yoghurt. Nowadays cheese and yoghurt makers
use pasteurized milk. This has been heated to kill any
bacteria. So they add their own bacteria to start off the
process. Enzymes in bacteria break down lactose into two simple sugars . Then other enzymes
convert the sugars into lactic acid.
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Confectionery
break down starch syrup into glucose syrup (carbohydrases are
used);
change glucose into fructose, which is sweeter so less is
needed and is used in 'slimming' foods (isomerase);
Biological detergents
break down stains (proteases attacks proteins and lipases attack
fats);
soften fabrics (cellulases break down the 'bobbly' bits that can form)
Meat
make the meat tender
Medical
treat cancer, make drugs such as synthetic penicillin , help in
digestion.
Key Vocabulary
enzyme
substrate
catalyst
product
Active site
Activation energy
Biotechnology
lipases
cellulases
proteases
isomerase
carbohydrases
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A. Match the following terms with their definitions by writing the correct letter in the
middle column:
Term
product
active site
enzyme
substrate
catalyst
activation energy
Definition
a. Amount of energy required for a chemical reaction to occur.
b. Substances that bring about a chemical reaction without
being changed itself.
c. Substances on which an enzyme acts.
d. Regions on the surface of enzymes that fit the substrate.
e. Substance formed from the substrate at the end of a
chemical reaction with an enzyme.
f. Proteins that speed up chemical reactions.
B. The illustration below shows how an enzyme works. Use the terms provided in the
box to place them in the correct place.
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C. Answer the following Questions:
1. Name 3 characteristics of enzymes.
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2. How do names of enzymes end? Give examples.
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3. What are enzymes named after. Give examples.
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4. Enzymes have an optimum temperature at which they work best. Temperatures
above and below this optimum will decrease enzyme activity. Which graph best
illustrates the effect of temperature on enzyme activity?
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D. (1)From the given illustration identify the following:
Substrate : ________________________________
Enzyme : _________________________________
Product : _________________________________
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(2) Given below is an enzyme and 4 different molecules .
Which molecule would most likely react with the enzyme?
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Explain your answer :
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Task 3 – Post Reading Activity
Complete the graphic organizer to show the various ways in which enzymes catalyze
Industrial processes
Biotechnology
What are the benefits of using enzymes as catalysts?
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