Intro to Metabolism

Metabolism

The totality of an organism’s chemical reactions

• Manage the materials and energy resources of a cell

Metabolic Rate

Total amount of energy an animal uses in a unit of time

In general, the _______ the organism, the _______ the metabolic rate

In general, the smaller the organism, the higher the metabolic rate

What is the necessity for enzymes in biological organisms

To allow reactions to happen quickly enough to be useful for living things….heating molecules to make reactions happen quickly is not practical

What does a metabolic pathway start and end with?

Beings with a specific molecule and ends with a product

True or False: Each step of a metabolic pathway is catalyzed by the same enzyme

False

• Each step is catalyzed by a specific enzyme

Catabolic Pathways

• Example?

Release energy by breaking down complex molecules into simpler compounds

• Digestive enzymes break down food → release energy

Anabolic pathways

Consume energy to build complex molecules from simpler ones

• Amino acids link to form muscle protein

Activation Energy (E_A)

The initial energy needed to start a chemical reaction

What is activation energy also called?

Free energy of activation

What does each chemical reaction involve?

Bond breaking and bond forming

What form is activation energy often in?

Thermal energy that the reactant molecules absorb from their surroundings

How to enzymes catalyze reactions by lowering the E_A barrier?

Enzymes do not affect the change in free energy (∆G); instead, they hasten reactions that would occur eventually

Bioenergetics

The study of how organisms manage their energy resources

Energy

The capacity to cause change/do work

Kinetic Energy

Energy associated with motion

Heat (thermal) Energy

Kinetic energy associated with random movement of atoms or molecules

Potential Energy

Energy that matter possesses because of its location or structure

Chemical Energy

Potential energy available for release in a chemical reaction

True or False: Energy can be converted from one form to another 

True

Thermodynamics

The study of energy transformations

• The energy of the universe is _____

  • Energy ____ be transferred and transformed

  • Energy _____ be created or destroyed

• The energy of the universe is constant

  • Energy can be transferred and transformed

  • Energy cannot be created or destroyed

Catalyst

A chemical agent that speeds up a reaction without being consumed by the reaction

Enzyme

A catalytic protein

Substrate

The reactant that an enzyme acts on

Enzyme-substrate complex

The structure that forms when an enzyme binds to its substrate

Active Site

The region on the enzyme where the substrate binds

• Important domain

Induced Fit

• What does the theory say?

Brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction

• Once the substrate and enzyme bind, that area gets smaller, strengthening the bond

In what specific ways can the active site can lower an E_A barrier?

• Orienting substrates correctly

• Straining substrate bonds

• Providing a favorable microenvironment (pH change)

• Covalently bonding to the substrate

What can an enzymes activity be affected by?

• General environmental factors, such as temperature and pH

• Chemicals that specifically influence the enzyme

What is the optimal temperature for human enzymes?

37° C

Continue at cofactors

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