BCLN BIOLOGY 12 – Rev July 2014
Unit 7 ~ Learning Guide
Name:________________
INSTRUCTIONS
Complete the following notes and questions as you work through the related lessons.
You are required to have this package completed BEFORE you write your unit test. Do
your best and ask questions about anything that you don't understand BEFORE you
write the unit test.
U7L1 NOTES: INTRODUCTION (web notes and video)
YOU SHOULD WATCH THE ENZYME LAB AND
THE MODULE EXAM VIDEO BEFORE PROCEEDING ANY FURTHER!
Definitions:
1. Metabolism - __________________________
_____________________________________
2. Enzymes - ___________________________
(speeds up certain chemical reactions).
a. Apoenzyme - _____________________
- It's shape accounts for an enzymes
ability to run only a single type of
reaction.
b. Coenzyme - ______________________
- can donate or accept atoms to or
from a reaction.
- Our body cannot often make
coenzymes, so we need them in
our diet. E.g.,________________
3. Substrate - ____________________________
_____________________________________.
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BCLN BIOLOGY 12 – Rev July 2014
4. Activation Energy - Many reactions will not
occur unless _____________ is added to
start the reaction off.
Example: A piece of wood needs an
input of energy to start it burning. This
input of energy is called the
______________________________
or energy of activation.
Thyroxin
The _________________________, located in the
neck, accumulates __________________ in order to
produce ___________________________________
________________________.
Thyroxin is a _________________________ that is
secreted into the ___________________ by cells of
the thyroid. It attaches to a _____________________
____________ on the surfaces of our body cells
where it governs the __________________________
_________________________________,
thus
having
an
overall
impact
on
__________________________
___________________________________________
_______________________.
Thyroxin does not have a target organ; it stimulates most of the cells
of the body to metabolize at a faster rate. The number of respiratory
enzymes increases, as does oxygen uptake. Thyroxin also helps
_____________________________
_____________________________________________.
Thyroglobulin is the storage form of __________________. Iodine is
required for Thyroglobulin to be made. No iodine, the thyroid gland
will increase activity as a mechanism to produce more thyroxin.
Unfortunately ____________________ ____________________.
Simple Goiter: A simple goiter occurs when __________________
_______________________________________________________
of the body through sufficient hormone production. The thyroid gland
compensates by enlarging, which usually overcomes mild
deficiencies of thyroid hormone.
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BCLN BIOLOGY 12 – Rev July 2014
Exothalmic goiter: _____________________ is characterized by excessive production
of thyroid hormone. ___________________________________
___________________________________ are characterized by an enlarged thyroid
gland and protrusion of the eyeballs. (Be sure you know where thyroxin is made, how it
affects the cells in the body, and how it affects metabolism)
U7L1 PRACTICE: INTRODUCTION
1. Create a web connecting the terms below. Please show how the terms are
connected (5 marks).
o Metabolism
o Enzyme
o Substrate
o Coenzyme
o Activation energy
a. Example web for the terms: mitochondria, energy, vesicles, Golgi bodies,
nucleus
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BCLN BIOLOGY 12 – Rev July 2014
b. Now your turn for: metabolism, enzyme, substrate, apoenzyme, coenzyme
and activation energy
2. Thyroxin is an important example of a hormone in our body:
a. Where is thyroxin made? (1 mark)
b. What is its function? (1 mark)
c. What is the effect of too little thyroxin? (1 mark)
d. What is the effect of too much thyroxin? (1 mark)
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BCLN BIOLOGY 12 – Rev July 2014
U7L2 NOTES: ENZYMES (web notes and video)
Lock and Key Theory of Enzyme Action
A. In order for a reaction to occur, the reactants (substrates) must be brought
____________________________.
B. The ______________________ bond to the __________________ on the
enzyme, and are brought close together. Sometimes the active site changes
shape to bring the substrates together.
C. The reaction occurs and the ____________________ are released. The enzyme
goes back to its normal tertiary configuration (shape).
According to this analogy, an enzyme acts like a ________ by combining with a specific
substrate and "_______________" the substrate for further activity of the cell.
This is a useful analogy because the key (_________) must have the correct
______________ to fit the lock (substrate). After the lock has been opened
(_______________________) the key (enzyme) is free and unchanged so that it may
be ___________________________ in the same manner. The portion of the enzyme
that is involved in the reaction is called the _____________________.
YOU SHOULD WATCH THE ENZYME STRUCTURE VIDEO, THE LOCK AND KEY
VIDEO, AND THE SUMMARY VIDEO BEFORE PROCEEDING ANY FURTHER!
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BCLN BIOLOGY 12 – Rev July 2014
Metabolic Pathway
Note: Metabolic Pathways are very
complex and multi-stepped with
intermediate products that are then use
as the reactant for the next step.
W = beginning substrate
X, Y = intermediate products/reactants
Z = final product
Number = Enzymes
Factors Affecting Enzyme Activity
A. Heavy Metals: Such as Pb+2 (lead) or Hg+2
(mercury) can bond with parts of enzymes
and cause them to change shape
(_________________ them). This bonding
is called ___________________________
_____________________.

The
enzyme
is
inactive
_________
____________________________
This is explained by a process in which the inhibitor fits into a place (site) on the
enzyme, which is different from the active site. When this happens, the folding of the
enzyme changes a little bit, and the _____________________________________ in a
way, which makes it a less effective catalyst. The enzyme can no longer bond to its
substrate so there is no chemical reaction.
B. Competitive Inhibition: Some molecules are shaped like a substrate and
compete with the ____________________ for the enzyme's active site. A
competitive inhibitor fits into the enzyme's _______________________ but
doesn't
react
with
anything
there.
This
prevents
the
correct
_______________________________________________________.
Example: Cyanide is an electron transport inhibitor
Since some of the enzymes get bonded to the "wrong" substrate, the
__________________ of "correct" production is reduced. Sometimes these molecules
only bond temporarily with the _________________, but sometimes they bond
permanently (for the life of the enzyme) rendering the enzyme useless.
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BCLN BIOLOGY 12 – Rev July 2014
If too many important enzymes are inactivated, the organism may ____________.
C. Temperature: ____________________________________________________
________________________________________________________________

Warm
temp
to
around 40oC speed
up reactions

High Temp –
________________
enzymes and cause
reactions to stop
If we increase the _____________ of the solution the enzyme is operating in, we will
typically see an increase in the reaction rate until a point is reached at which the
enzyme __________________________. This is a result of breaking hydrophobic
bonds as the increase in temperature causes the enzyme's structure to
"__________________" around. The enzymes active site changes shape so that it can
no longer bond to its substrate and as a result there is no chemical reaction.
D. pH: ____________________________________________________________
________________________________________________________________

Any other pH affects
tertiary structure (shape
of the active site) of the
enzyme and slows down
reactions. Too much of a
change
____________________
__ the enzyme so it can
no longer bond to its
substrate and stops the
reaction.

To the right are examples
of
various
enzymes
showing their optimum pH
levels:
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BCLN BIOLOGY 12 – Rev July 2014
E. Substrate Concentration: __________________________________________
________________________________________________________________.

If we do a series of
experiments arranged so the
concentration of the enzyme
is always the same, but the
substrate
(reactant)
concentration is increased
from one experiment to the
next, we find that in the
_______________________
_______________________
the rate increases as we
increase substrate concentration. However as the experiments involve
higher and higher substrate concentrations, we find that we
_____________________________________________. More substrate
doesn't increase the rate any more. At this point, we say that the enzyme
is _________________ (it can't handle any more). To increase the rate
again, we'd need more ___________________.
F. Enzyme Concentration - _______________________________________
_____________________________________________________________.

What happens if we change the concentration of an enzyme? More
catalyst means a faster ________________, so the reaction rate
increases. (Reaction rate is basically "how much substrate reacts in a
particular amount of time, usually a ________________).
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BCLN BIOLOGY 12 – Rev July 2014
U7L2 PRACTICE: ENZYMES
1. Complete the following table by giving the name for the enzyme that acts on
each substrate listed. (3 marks).
Substrate
Enzyme
Maltose
Peptides
Nucleic Acids
Neutral Lipids
Acetylcholine
Starch
2. Chemical reactions in cells occur at lower temperatures because enzymes
___________________ the activation energy for the reaction. (1 mark)
3. Label the diagram with the following terms: enzyme, substrates, co-enzyme,
enzyme-substrate complex, product, and activation site. (6 marks)
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BCLN BIOLOGY 12 – Rev July 2014
4. The ____________________________ on an enzyme is the region where the
substrate fits with the proper geometry for a reaction to occur. This “fit” between
the enzyme and substrate is called the ____________________________
model. (2 marks)
5. Explain the lock and key model of enzyme action. Why does denaturation of the
enzyme prevent it from functioning properly? (2 marks)
6. Compare and contrast competitive versus non-competitive inhibition. (2 marks)
7. List two environmental factors that can change the shape of an enzyme. (2
marks)
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BCLN BIOLOGY 12 – Rev July 2014
8. Label the vertical and horizontal axes in the following diagrams. (6 marks)
a.
b.
c.
PLEASE REMEMBER:
YOU MUST PERFORM AND SUBMIT THE ENZYME LAB BEFORE THIS
UNIT IS COMPLETE! REFER TO THE UNIT 7 DROP-DOWN MENU TO
ACCESS THE LAB GUIDE AND LAB.
~ END OF BIOLOGY 12 UNIT 7 LEARNING GUIDE ~
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BCLN BIOLOGY 12 – Rev July 2014
UNIT 7 ANSWER KEY
U7L1 PRACTICE: INTRODUCTION
1. Create a web connecting the terms below. Please show how the terms are connected (5 marks).
o Metabolism
o Enzyme
o Substrate
o Coenzyme
o Activation energy
Answers will vary. One possible example
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BCLN BIOLOGY 12 – Rev July 2014
2. Thyroxin is an important example of a hormone in our body:
a. Where is thyroxin made? (1 mark)
= thyroid
b. What is its function? (1 mark)
= regulate oxygen consumption and therefore, overall rate of metabolism
c. What is the effect of too little thyroxin? (1 mark)
= hypothyroidism…slower metabolism, lethargic, weight gain, enlarged
thyroid
d. What is the effect of too much thyroxin? (1 mark)
= hyperthyroidism…faster metabolism, "nervous energy", weight loss, bulging
eyes, enlarged thyroid
U7L2 PRACTICE: ENZYMES
1. Complete the following table by giving the name for the enzyme that acts on each substrate
listed. (3 marks).
Substrate
Enzyme
Maltose
maltase
Peptides
peptidases
Nucleic Acids
nucleases
Neutral Lipids
lipases
Acetylcholine
acetylcholinesterase
Starch
amylases
2. Chemical reactions in cells occur at lower temperatures
___________________ the activation energy for the reaction. (1 mark)
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because
enzymes
BCLN BIOLOGY 12 – Rev July 2014
3. Label the diagram with the following terms: enzyme, substrates, co-enzyme, enzyme-substrate
complex, product, and activation site. (6 marks)
activation
co-enzyme
substrates
enzyme-substrate
complex
product
site
enzyme
4. The ____________________________ on an enzyme is the region where the substrate fits with
the proper geometry for a reaction to occur. This “fit” between the enzyme and substrate is called
the ____________________________ model. (2 marks)
5. Explain the lock and key model of enzyme action. Why does denaturation of the enzyme prevent
it from functioning properly? (2 marks)
= the three dimensional shape of the enzyme's activation site is complimentary and
specific to the three dimensional shape(s) of its substrate(s)
= when an enzyme is denatured its three-dimensional shape is altered, typically such
that it no longer compliments its substrate(s) three-dimensional shape(s), and thus,
it can no longer bind to the substrate(s) to lower the reaction's activation energy
and speed up (catalyze) the reaction.
6. Compare and contrast competitive versus non-competitive inhibition. (2 marks)
= competitive inhibition is when a substance, other than the substrate itself, competes
with and binds to the active site of the substrate's enzyme, when the competitive
inhibitor binds to the enzyme's active site the substrate can no longer do so and thus,
the enzyme cannot effectively catalyze the reaction and the reaction rate slows down
(common regulatory mechanism often involving a negative feedback loop)
= non-competitive inhibition is when a substance, other than the substrate itself, binds
to an alternate site (allosteric site as opposed to the active site) on the substrate's
enzyme, when the non-competitive inhibitor binds to the enzyme's allosteric site it
alters the enzyme's three dimensional structure including its active site such that the
substrate can no longer bind to the enzyme and thus, the enzyme cannot effectively
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BCLN BIOLOGY 12 – Rev July 2014
catalyze the reaction and the reaction rate slows down (another common regulatory
mechanism often involving a negative feedback loop)
7. List two environmental factors that can change the shape of an enzyme. (2 marks)
= change in pH (addition of either H+ or OH- ions to the solution surrounding the
enzyme as it tends to interfere with hydrogen bonds that influence the enzyme's
three dimensional shape)
= increase in temperature (tend to disrupt bonds influencing the enzyme's three
dimensional shape)
8. Label the vertical and horizontal axes in the following diagrams. (6 marks)
Temperature °C
Reaction Rate (variable units)
b.
Subtrate Concentration
(variable units)
c.
Reaction Rate (variable units)
Reaction Rate (variable units)
a.
pH
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