Biology
Enzymes
Name: _____________ Period: ___ Date:________
VIDEO: Brainpop and Enzymes (http://youtu.be/CZD5xsOKres)
1. After watching the videos on enzymes, describe in your own words what an
enzyme is.
2. Why do you need enzymes?
ENZYMES:
YOU CAN’T LIVE WITHOUT THEM!
PART I: Background Information
All living things have mechanisms that allow them to maintain a stable
internal environment. Without these mechanisms organisms can die. The
maintenance of internal conditions is known as homeostasis. Organisms have
regulatory systems that maintain internal conditions, a large part of which are
enzymes that reduce the amount of energy needed by cells for chemical reactions
to take place. Without the aid of enzymes, an organism’s metabolism (the sum of
all the chemical reactions within the organism – including the breakdown and build
up of molecules) would occur too slowly to sustain life.
Fill in the chart in your notes with the
Enzymes are a class of proteins, which are able to aid in the completion of
chemical reactions. Enzymes are known as catalysts. Catalysts increase the rate
of chemical reactions, without which the reaction would occur very slowly. Enzymes
are highly specific in their catalytic activity, meaning that certain enzymes work
with certain substrates (the substance being acted on by the enzyme – example –
fat molecules are the substrate for the fat enzyme). The reason that they are said
to be so specific is because the enzyme and substrate fit closely together. The
three-dimensional fit of the enzyme-substrate complex helps chemical reactions
occur by lowering the energy needed to complete the joining or breaking of the
substrate to make the desired products. Once the chemical reaction is complete,
the enzyme and substrate separate. The substrate has changed during the
reaction, but the enzyme remains the same allowing it to react with another
substrate until all the substrate has been changed into the desired product.
Fill in the chart in your notes with the
3. Explain what happens to the enzyme and substrate after the
chemical reaction has taken place.
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Enzymes are very sensitive proteins. An enzyme’s three-dimensional shape
is due to weak bonds between amino acids that cause the folding and twisting of the
Biology
Enzymes
Name: _____________ Period: ___ Date:________
amino acids chain that comprises the enzyme. These weak bonds can be broken
by changes in pH and temperature. Under harsh conditions such as extreme
temperature and pH levels, the enzyme becomes denatured, or inactive. Once
denaturing occurs the enzyme is no longer able to fit with the substrate and acts as
a catalyst for chemical reactions. Depending on its location in the body, each
enzyme has an optimum pH and temperature at which it works best.
Answer the following in completely.
4. What are the subunits or building blocks of enzymes?
_________________ ___________
5. What happens to an enzyme under harsh conditions? ____________
6. What is meant by an enzymes optimum temperature?
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Fill in the chart in your notes with the
Starches are complex carbohydrates that are found in food such as rice,
potatoes, bread and crackers. Digestion of carbohydrates, such as starches, begins
in your mouth when it mixes with your saliva. The digestive process is completed
in the small intestine. Amylase is an enzyme found in saliva that breaks down
starches into simple sugars. (Just as with amylase, most enzymes end in the suffix
“ase”). Amylase is a catalyst, because it causes a chemical reaction to take place
quickly without being changed by the reaction. That very same enzyme will do the
same thing the next time a starchy food is eaten. Without enzymes such as
amylase, our metabolism would occur too slowly to sustain life.
7. The amylase enzyme found in _______________ breaks
_____________down into _________________________.
8. How could our metabolism be affected if there were no enzymes?
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PART II: KNOW YOUR PH
pH is one of the factors that can influence an
enzyme’s ability to function. The pH of a
substance also has a tremendous affect on its
properties. For instance, you wouldn’t drink
vinegar to calm an upset stomach or use soap
to dissolve metal. Vinegar is an example of
an acid, whereas the chemicals in soap are
mostly bases. An acid is a substance that
typically tastes sour and a base is a
substance that can leave a slimy or soapy
feeling on your fingers. pH is the measure of
the acidity of a solution. Examine the pH
Biology
Enzymes
Name: _____________ Period: ___ Date:________
scale. Acids are found from pH 0 – pH 6.99. pH of 7 is neutral, and a pH of 7.0114 is bases.
JUST REMEMBER: A goes with B
Acids are Below 7
Bases are Above 7
9. Which is more acidic, stomach acid or tomatoes? ____________________
10.A substance with a pH of 8.7 is a(n) _______________________
11.Which substance is closest to neutral; black coffee (pH 4.8), human saliva
(pH of 6.9), baking soda (pH of 9) or oven cleaner (pH of 13)? The substance
closest to neutral is ____________________.
12.If a student measures the pH of stomach acid and the pH of oven cleaner the
pH of stomach acid would be (above / below) 7, but the pH of oven cleaner
would be (above / below) 7.
13.What is the weakest acid listed on the diagram? ______________________
14.What is the pH of the strongest base listed on the diagram? ____________
ANALYSIS
15.What temperature and pH does amylase work best at? Explain
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16.Rain water has a pH of 5.8, is it acidic or basic? Explain your answer.
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EXTENSION
17.What is the pH of pure water? With that in mind, do you think the pH of
body fluids (sweat, blood, saliva, urine etc) is mostly acidic, mostly basic or
mostly neutral? Explain why.
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Biology
Enzymes
Name: _____________ Period: ___ Date:________
Enzyme Shapes: Read and Answer the questions
Enzymes are proteins that act as catalysts in living cells. Enzymes are also very
“picky” molecules and only work on one substrate.
1. The substrate for a particular reaction is shown below. In the box labeled
“Enzyme,” predict the shape of the enzyme that will react with this substrate.
Draw the enzyme in the space provided.
SUBSTRATE
ENZYME
2. Explain the significance of the shape of the enzyme that you just drew.
3. In the box below, predict the shape of the enzyme AFTER the reaction has taken
place. Draw it in the box below. Explain your prediction in the space provided.
 ENZYME AFTER REACTION
4. In the box below, predict the shape of the substrate AFTER the reaction has
taken place. Draw it in the box below. Explain your prediction in the space
provided.
 SUBSTRATE AFTER REACTION