The most important metabolic fuel in the human body is: A. Sucrose B. Starch C. Protein D. Cellulose E. Glucose

When two monosaccharides undergo a condensation reaction: A. a new monosaccharide is formed B. a disaccharide is formed C. a polysaccharide is formed D. a starch is formed E. hydrolysis occurs

Metabolism & Enzymes Constraints on Reactions Making Reactions Possible with ATP Making Reactions Probable with Enzymes Why does Grandma take St. Joseph’s?

What is Metabolism? All the chemical reactions of the body

What is Metabolism? All the chemical reactions of the body Catabolism breaking large molecules into smaller molecules (hydrolysis) releases energy (an exergonic process)

What is Metabolism? All the chemical reactions of the body Catabolism breaking large molecules into smaller molecules (hydrolysis) releases energy (an exergonic process) Anabolism builds a large molecule from smaller ones (dehydration synthesis/condensation) consumes energy (an endergonic process)

Metabolism & Enzymes Constraints on Reactions Making Reactions Possible with ATP Making Reactions Probable with Enzymes Why does Grandma take St. Joseph’s?

Constraints on Reactions First Law of Thermodynamics Energy can be converted from one form to another, but it cannot be created or destroyed Chemical energy is stored in macromolecules we eat When bonds are broken, energy is released We use this energy to power our bodies

Constraints on Reactions First Law of Thermodynamics Energy can be converted from one form to another, but it cannot be created or destroyed Chemical energy is stored in macromolecules we eat When bonds are broken, energy is released We use this energy to power our bodies Second Law of Thermodynamics In every energy transfer, some energy is lost as heat Unless our bodies obtain energy from our surroundings, we lose energy over time (entropy)

To counter the loss of energy (as heat), we add energy to our bodies in the form of food

Using ATP to Build Macromolecules

Using ATP to Build Macromolecules endergonic exergonic

ATP is Recycled (Breakdown of food)

Metabolism & Enzymes Constraints on Reactions Making Reactions Possible with ATP Making Reactions Probable with Enzymes Why does Grandma take St. Joseph’s?

Enzymes are Everywhere

Enzymes are Biological Catalysts Enzymes are proteins that function as biological catalysts Increase the speed of chemical reactions Increase likelihood of chemical reactions

Enzymes are Biological Catalysts Enzymes are proteins that function as biological catalysts Increase the speed of chemical reactions Increase likelihood of chemical reactions Can increase rate of chemical reactions by over 1,000,000X

Enzymes Bind to Substrates Bind with one or more reactants, termed substrates

Enzymes Bind to Substrates Bind with one or more reactants, termed substrates Enzymes are named after the substrate with which they bind -ase forms the suffix (e.g., the enzyme amylase digests the starch amylose)

How do Enzymes Work? Enzymes can affect reactions by: 1) Placing reactants in proper orientation 2) Create environment that promotes the reaction 3) Chemically weakening the bonds within the reactants 4) Donating electrons or protons to the reactants

How do Enzymes Work? Enzymes can affect reactions by: 1) Placing reactants in proper orientation 2) Create environment that promotes the reaction 3) Chemically weakening the bonds within the reactants 4) Donating electrons or protons to the reactants Enzymes catalyze specific reactions

How do Enzymes Work? Enzymes can affect reactions by: 1) Placing reactants in proper orientation 2) Create environment that promotes the reaction 3) Chemically weakening the bonds within the reactants 4) Donating electrons or protons to the reactants Enzymes catalyze specific reactions Enzymes are reusable (i.e. recycled)

Enzymatic Reactions

Cofactors Cofactors bind to enzyme and change its shape, creating an active site (e.g., iron, copper, zinc, magnesium or calcium ions)

Cofactors Cofactors bind to enzyme and change its shape, creating an active site (e.g., iron, copper, zinc, magnesium or calcium ions) Vitamins are used to make organic cofactors called coenzymes. Many enzymes cannot function without cofactors.

Rate of Enzymatic Reactions The basis for chemical reactions is molecular and collision Molecular Motion Animation

Rate of Enzymatic Reactions Rates of reactions are affected by various factors: Substrate and enzyme concentration Temperature pH Why do these influence reaction rates?

Enzyme/Substrate Concentration Slow at low concentration Enzyme

Enzyme/Substrate Concentration Slow at low concentration Increase until point of saturation Why does saturation occur? Enzyme

Temperature Slow at low temperatures Reaction Rate Temperature (°C)

Temperature Slow at low temperatures Slow at high temperatures Explain rate at each arrow Reaction Rate Temperature (°C)

pH Enzymes function best within a specific pH range Why does pH alter enzyme function?

Competitive Inhibition Slow down enzyme function Effect is reversible Substrate Active Site Inhibitor Enzyme Enzyme

Non-Competitive Inhibition Binds to enzyme away from active site Substrate Enzyme Inhibitor

Non-Competitive Inhibition Binds to enzyme away from active site Substrate no longer binds to active site Irreversible damage to enzyme function - Mercury, Cyanide Substrate Enzyme Inhibitor

Metabolism & Enzymes Constraints on Reactions Making Reactions Possible with ATP Making Reactions Probable with Enzymes Why does Grandma take St. Joseph’s?

Aspirin is a Non-Competitive Inhibitor Inhibits COX enzyme, which functions in blood platelet aggregation What do blood platelets do? Hence, Aspirin reduces risk of a heart attack

Patient Profile: Laurie Ate a Cheese Omelet, Blueberry yogurt, and 2 glasses of chocolate milk at IHOP Symptoms: Diarrhea, Nausea, Stomach Ache What do you think Laurie suffers from?

Summary Building macromolecules, is an anabolic process that requires energy released from the catabolism of adenosine triphosphate (ATP) Enzymes bring together reactants and create an environment that favors a reaction Like any protein, the structure of an enzyme is critical to its function. Environmental conditions, cofactors, and inhibitors alter the structures of enzymes and hence alter their functions