Warm-up

1
Warm-up

• What are the four macromolecules and their
  function?

2
Mindstretcher

• 1. What is the name of the region at which
  reactants bind to an enzyme during a biochemical
  reaction?
• a) Catalyst
• b) Product
• c) Substrate
• d) Active site

3
Mindstretcher

• 2. How are enzymes able to speed up biochemical
  reactions?
• a) They provide energy to the reactants.
• b) They absorb energy from the products.
• c) They lower the activation energy of the
  reaction.
• d)They increase the number of available reactant
  particles.

4
Mindstretcher

• 3. The diagram below shows a single glucose
  molecule.
• This molecule is also referred to as
• a) A polysaccharide
• b) A monosaccharide
• c) A fatty acid
• d)A nucleic acid

5
Enzymes
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Metabolism

• The totality of an organisms chemical processes,
  involving thousands of precisely coordinated,
  complex, efficient and integrated chemical
  reactions in the cell.

7
Enzymes are biological catalyststhey make all
the chemical reactions happen in the cell!
8
Enzymes biological catalysts

• Catalyst chem agent that accelerates a reaction
  without being permanently changed
• Protein
• Specific
• Reusable

9

• Catalyst something that speeds up a chemical
  reaction
• Enzyme proteins that speed up/help jump start
  reactions in an organism
• Therefore enzymes are catalysts because they
  speed up biochemical reactions
• We need enzymes for every process that happens in
  our bodies!
• e.g. Digesting food, replicating DNA

10
Enzymes

• Substrate the material that an enzyme binds to
  and breaks down
• Complex enzyme and substrate together
• Active site Where the enzyme and substrate bind
  together

11
Enzymes

• Enzymes often end in -ase
• Lactase breaks down lactose
• Amylase breaks down amylose
• Make up your own enzyme-substrate names. Write on
  your paper

12
Quick Check

• 1. Whats a substrate?
• 2. What do enzymes usually end in?
• 3. Is catalase an enzyme or a substrate? How do
  you know?
• 4. What do you predict is the substrate for the
  enzyme sucrase?

13
Enzyme Specificity

• Enzymes are specific
• They only work with one substrate
• The enzyme and the substrate fit together like a
  lock and a key
• Enzymes are reusable meaning _________
• therefore the enzyme is not changed during a
  reaction
• The substrate is changed, it becomes the
  product(s)

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Activation Energy

• For reaction to occur, reactants must absorb
  energy to break bonds
• Activation Energy is the amount of energy
  reactant molecules must absorb to start a
  chemical reaction.

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Enzymes Lower Activation Energy

• Stress bonds for catabolism (breakdown)
• Orient molecules for anabolism (building)
• Provide microenv. that facilitates the reaction

16
Catalytic Cycle of Enzymes
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Factors Affecting Enzyme Activity

• Enzymes are proteins
• Proteins are long chains of amino acids
  foldedinto a very specific shape
• The function of every protein depends on
  itsstructure or shape
• Change the shape of an enzyme and it wont work
• What would change the shape of an enzyme?

18
Factors Affecting Enzyme Activity

• Temperatureincrease temp, increase reaction
  rate, until heat denatures protein
• pH most optimal from 6-8
• Ionic conc. most enz cannot tolerate high
  salinity
• Many adaptations are exceptions to above

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Destroying Enzymes

• Denature enzyme changes shape so that it no
  longer works properly

An enzymes job is determined by its SHAPE
Enzymes are denatured by high temperatures and
low pHs.
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Optimum Temperature and pH

1. Find the highest point on the curve.
2. Drop down to the x-axis.
3. Record temperature or pH.

21
Factors Influencing Rate of Enzyme Action pH

• pH - the optimum (best) in most living things is
  close to 7 (neutral)
• high or low pH levels usually slow enzyme
  activity
• A few enzymes (such as gastric protease) work
  best at a pH of about 2.0

22
Factors Influencing Rate of Enzyme Action
Temperature

• Temperature - strongly influences enzyme activity
  
• optimum temperature for maximum enzyme function
  is usually about 35-40 C.
• reactions proceed slowly below optimal
  temperatures
• above 45 C most enzymes are denatured (change in
  their shape so the enzyme active site no longer
  fits with the substrate and the enzyme can't
  function)

23
Factors Influencing Rate of Enzyme Action
Concentrations of Enzyme and Substrate

• When there is a fixed amount of enzyme and an
  excess of substrate molecules -- the rate of
  reaction will increase to a point and then level
  off.

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Enzymes (Notes)
enzyme
lactase
glucose galactose
lactose H2O
substrate
products
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Enzyme Foldable
SUBSTRATES A B
ENZYME-SUBSTRATE COMPLEX
1
2
ENZYME
\
PRODUCT AB
3
4
ENZYME
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TAB 1

• ENZYME proteins that act as catalyst to speed up
  chemical reactions in living cells.
• SUBSTRATE the substance and enzyme acts on

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Tab 2

• Induced Fit
• ACTIVE SITE a region of an enzyme molecule
  which the substrate binds to
• A change in the shape of an enzymes active site
• Induced by the substrate

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Tab 3

• Factors that Affect Enzyme Action
• pH
• Temperature
• Amount of substrate

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Tab 4

• Reusable or NOT reusable? Reusable
• Specific or not specific? Specific
• Effect on chemical bonds that join atoms in
  molecules
• Break bonds or
• Make bonds
• What macromolecule? Enzymes always protein
• Examples of biological catalysts Protease,
  Lactase, Amylase

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ReviewQuiz!
31
Question 1
What are proteins that speed up chemical
reactions called?
A. Amino acids B. Reactants C. Enzymes D.
Substrates
32
Question 2
What is a substrate?
A. The compound that is before the arrow in a
chemical reaction B. Another name for an
enzyme C. The material that an enzyme binds to
D. The term used to describe the structure
formed after an enzyme binds with a complex
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Question 3
How do enzymes affect the activation energy of a
chemical reaction?
A. Enzymes increase the activation energy needed
for a reaction to start B. Enzymes decrease the
activation energy needed for a reaction to
start C. Enzymes do not alter activation energy
of chemical reactions D. Enzymes initially
decrease activation energy than increase it
34
Question 4
Which of the following statements best describes
enzymes?
A. enzymes cannot be reused after a reaction B.
Enzymes are organic catalysts C. Enzymes slow
down chemical reactions D. Enzymes can bind to
any substrate
35
Question 5
An enzymes job is determined by its what?
A. size B. shape C. color D. Activation energy
36
Answers
37
Question 1
What are proteins that speed up chemical
reactions called?
A. Amino acids B. Reactants C. Enzymes D.
Substrates
38
Question 2
What is a substrate?
A. The compound that is before the arrow in a
chemical reaction B. Another name for an
enzyme C. The material that an enzyme binds to
D. The term used to describe the structure
formed after an enzyme binds with a complex
39
Question 3
How do enzymes affect the activation energy of a
chemical reaction?
A. Enzymes increase the activation energy needed
for a reaction to start B. Enzymes decrease the
activation energy needed for a reaction to
start C. Enzymes do not alter activation energy
of chemical reactions D. Enzymes initially
decrease activation energy than increase it
40
Question 4
Which of the following statements best describes
enzymes?
A. enzymes cannot be reused after a reaction B.
Enzymes are organic catalysts C. Enzymes slow
down chemical reactions D. Enzymes can bind to
any substrate
41
Question 5
An enzymes job is determined by its what?
A. size B. shape C. color D. Activation energy