introduction to metabolism. metabolism includes all of the chemical reactions in an organism. ...
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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.
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