Warm-up

•What are the four macromolecules and their function?

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

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.

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

Mindstretcher

EnzymesEnzymes

Metabolism

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

Enzymes are “biological catalysts”:they make all the chemical reactions happen

in the cell!

Enzymes = “biological catalysts”

•Catalyst = chem agent that accelerates a reaction without being permanently changed

•Protein

•Specific

•Reusable

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

Enzymes 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

EnzymesEnzymesEnzymes often end in -ase

•Lactase breaks down lactose

•Amylase breaks down amylose

•Make up your own enzyme-substrate names. Write on your paper

Quick CheckQuick Check1. What’s 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?

Enzyme SpecificityEnzyme SpecificityEnzyme SpecificityEnzyme SpecificityEnzymes 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)

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.

Enzymes Lower Activation Energy•Stress bonds for

catabolism (breakdown)

•Orient molecules for anabolism (building)

•Provide microenv. that facilitates the reaction

Catalytic Cycle of Enzymes

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 won’t work

•What would change the shape of an enzyme?

Factors Affecting Enzyme Activity

•Temperature—increase 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

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

Destroying EnzymesDestroying EnzymesAn enzyme’s job is determined by its SHAPE

Enzymes are denatured by high temperatures and low pHs.

Optimum Temperature and pH

1. Find the highest point on the curve. 2. Drop down to the x-axis.

3. Record temperature or pH.

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

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)

Factors Influencing Rate of Enzyme Action: Temperature

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.

lactose + H2O glucose + galactose

lactase

substrate

enzyme

products

Enzymes (Notes)Enzymes (Notes)

\

Enzyme FoldableSUBSTRATES A &

B

ENZYME

ENZYME-SUBSTRATE COMPLEX

PRODUCT AB

ENZYME

1 2

3 4

TAB 1• ENZYME: proteins that act as catalyst to speed

up chemical reactions in living cells.

• SUBSTRATE: the substance and enzyme acts on

Tab 2Induced Fit:

ACTIVE SITE: a region of an enzyme molecule which the substrate binds to

•A change in the shapeshape of an enzyme’s active site

•Induced Induced by the substrate

Tab 3Factors that Affect Enzyme

Action:

•pH

•Temperature

•Amount of substrate

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

ReviewQuiz!

Question 1

What are proteins that speed up chemical reactions called?

A. Amino acidsB. Reactants C. EnzymesD. Substrates

Question 2 What is a substrate?

A. The compound that is before the arrow in a chemical reactionB. Another name for an enzymeC. The material that an enzyme binds to D. The term used to describe the structure formed after an enzyme binds with a complex

Question 3 How do enzymes affect the activation energy of

a chemical reaction?A. Enzymes increase the activation energy needed for a reaction to startB. Enzymes decrease the activation energy needed for a reaction to startC. Enzymes do not alter activation energy of chemical reactionsD. Enzymes initially decrease activation energy than increase it

Question 4

Which of the following statements best describes enzymes?

A. enzymes cannot be reused after a reactionB. Enzymes are organic catalystsC. Enzymes slow down chemical reactionsD. Enzymes can bind to any substrate

Question 5

An enzymes job is determined by its what?

A. sizeB. shapeC. colorD. Activation energy

Answers

Question 1

What are proteins that speed up chemical reactions called?

A. Amino acidsB. Reactants C. EnzymesD. Substrates

Question 2 What is a substrate?

A. The compound that is before the arrow in a chemical reactionB. Another name for an enzymeC. The material that an enzyme binds to D. The term used to describe the structure formed after an enzyme binds with a complex

Question 3 How do enzymes affect the activation energy of

a chemical reaction?A. Enzymes increase the activation energy needed for a reaction to startB. Enzymes decrease the activation energy needed for a reaction to startC. Enzymes do not alter activation energy of chemical reactionsD. Enzymes initially decrease activation energy than increase it

Question 4

Which of the following statements best describes enzymes?

A. enzymes cannot be reused after a reactionB. Enzymes are organic catalystsC. Enzymes slow down chemical reactionsD. Enzymes can bind to any substrate

Question 5

An enzymes job is determined by its what?

A. sizeB. shapeC. colorD. Activation energy