ENERGYIntroduction to Metabolism

Metabolism

Includes all of the chemical reactions in an organism.

Reactions are ordered in metabolic pathways (sequence of steps)

Each step is controlled by an enzyme that converts a specific molecule into a product.

Metabolism Through metabolic

pathways, the cell transforms and creates the organic molecules that provide energy for life.

Metabolism

Catabolic Pathways release energy stored in complex molecules through breaking down these molecules into simpler compounds.

Proteins, Carbs &

Lipids

Metabolism

Anabolic Pathways require energy to combine simpler molecules into more complicated ones. (Building up)

Amino Acids Proteins

Metabolism

The energy released from catabolic pathways drives anabolic pathways in the cell.

RESPIRATION BIOSYNTHESIS Glucose CO2 + H2O Monomers

Macromolecules

CATABOLIC REACTIONS ANABOLIC REACTIONS

(Exergonic) (Endergonic)

ATP

Forms of Energy

Energy is the ability to cause change. Some forms of energy can do work such

as moving matter against an opposing force.

Forms of Energy

Kinetic Energy is the energy of Motion. Falling rocks, orbiting planets, air

molecules.

Forms of Energy

Potential Energy is stored energy as a result of location or arrangement of matter.

A rock perched on ledge, standing on a diving board.

Forms of Energy

Chemical Energy is a form of potential energy stored in the arrangement of atoms in molecules.

Forms of Energy

Light Energy/ radiative energy carried by light.

Light can alter molecules in our eyes allowing us to see.

Light is the only energy we can see.

Forms of Energy

Energy can be converted from one form to another.

Plants convert light energy to chemical energy ( the potential energy of ATP).

When climbing up a hill kinetic energy of muscle movement becomes potential energy.

Thermodynamics

The laws of energy transformation. 1st Law of Thermodynamics – the total

amount of energy in the universe or any process remains constant. Energy can change form but can neither be created nor destroyed.

Thermodynamics

2nd Law of Thermodynamics – in any process, the amount of energy available to do work decreases, such as when heat is released.

Heat is the random movement of molecules.

As a process occurs heat is the energy that can no longer do work.

Thermodynamics

An organism takes in large molecules to use for energy and releases Heat and smaller molecules like CO2 and water into the environment.

Free Energy

Free Energy (G) is the energy available to do work

Each chemical has a certain amount of free energy.

Each chemical reaction involves a change in free energy. ∆G

∆G = Gproducts - Greactants

Free Energy

Exergonic reactions release energy and the free energy decreases. -∆G

Exergonic reactions occur spontaneously.

Downhill Reaction

C6H12O6 + 6O2 6 CO2 + 6 H2O + ATP

Exergonic Reaction

Free Energy

Endergonic reactions absorb energy from the surroundings, and stores the free energy in molecules. +∆G

Endergonic reactions are not spontaneous and require ENERGY

Uphill Reaction

Endergonic Reaction

Exergonic vs. Endergonic

Free Energy

Free energy, energy available to do work depends on the concentration of molecules.

The greater the difference in concentration of molecules on either side of a barrier (Cell Membrane) the more work that can be done.

Concentration Gradient

Equilibrium

Eventually, in a closed system, reactions reach equilibrium and then can do no more work ∆G = 0.

A cell that has reached metabolic equilibrium is DEAD!

Metabolism as a whole is never at equilibrium.

Equilibrium

The constant flow of materials in and out of the cell is essential to LIFE.

As long as our cells have a steady supply of glucose, other fuels and oxygen and are able to get rid of waste, their metabolic pathways never reach equilibrium.

ATP

ATP (Adenosine triphosphate) powers cellular work by coupling exergonic reactions to endergonic reactions.

Exergonic reactions are used to power endergonic ones.

A cell uses ATP as immediate energy.

ATP

Structure of the ATP molecule

Hydrolysis of ATP

Can be hydrolyzed to ADP (Adenosine diphosphate) and an inorganic phosphate.

Releases 7.3 kcal of energy.

ATP + H2O ADP + Pi + ENERGY

Hydrolysis of ATP

In a cell, the free energy released from the hydrolysis of an ATP molecule is used to transfer the phosphate group to another molecule producing a phosphorylated molecule that is more reactive (less stable).

This phosphorylation forms the basis for almost all cellular work.

Hydrolysis of ATP

Phosphorylation of a Glucose molecule traps glucose inside of the cell.

Regeneration of ATP

A cell regenerates ATP constantly. The formation of ATP from ADP and Pi is

endergonic (+∆G) Cellular Respiration provides the energy

for the regeneration of ATP. Plants can also produce ATP using light

energy.