UNIT 2: Metabolic Processes Intro to Metabolism, Energy, ATP and

Redox

MetabolismLiving organisms must constantly capture, store

and use energy to carry out the functions of life.At any given instant an organism is breaking

down macromolecules(catabolic reactions) to release energy, and synthesizing macromolecules (anabolic reactions) which requires energy.

The sum of all anabolic and catabolic processes in a cell or organism is called METABOLISM.

Energy TransferEnergy is not easy to obtain; often it is

captured in one form and converted to another before it is used.

Ex. Plants use photosynthesis to convert light energy to glucose.

Ex. Plants and animals use cellular respiration to change macromolecules, like carbohydrates, into a source of useable energy, ATP.

The First Law of ThermodynamicsThe total amount of the energy in the universe

is constant. Energy cannot be created or destroyed, but

only converted from one form to another.

EnergyChemical Potential energy is energy stored in

bonds.Free energy is energy that can do work.

It is _____________ when a bond is broken and _____________ when a new bond is made.

ATP: Useable EnergyATP is a prime energy

carrying molecule. ATP is used to create

free energy for the cell.

ATP is a nucleotide composed of adenine (nitrogenous base), ribose (pentose) and three phosphate groups (P groups).

Hydrolysis of ATPThe removal of the terminal P group

from ATP by hydrolysis in the presence of ATPase (enzyme), forms ADP and an inorganic phosphate group (Pi) and releases free energy for the cell.

ATPase

PhosphorylationThe energy is not given off as heat or

the cell would die. It is immediately coupled with a reaction which uses the energy.

Phosphorylation: the terminal P, and it’s high energy bond, are attached to a new molecule.

Phosphorylation makes the molecule more reactive.

PhosphorylationAn example of this process is in active

transport, ATP’s phosphate group is removed and then phosphorylated to protein carriers, changing their shape and letting ions into or out of the cell against the concentration gradient.

Redox Reactions (Biol.Rxn Type #3)Much of the ATP created by the cell is a result of

redox reactions; a reaction in which one atom transfers an electron/electrons to another atom. Oxidation and reduction both occur.

Oxidation: a process in which an atom loses one or more electrons (aka: the Reducing agent)

Reduction: a process in which an atom gains one or more electrons (aka: the Oxidizing agent)

LEO the lion says GER or OIL RIG

Oxidation-Reduction Reactions

Ionic ReactionsRedox is easily seen

in ionic reactions.

Redox in Covalent SystemsRedox is more difficult to see in a covalent

system.In covalent systems reactions, the unequal

sharing of electrons in a polar bond is considered to be a loss or a gain of electrons.

Easiest to see in combustion reactions (fig 13 p67):

CH4 (g) + 2O

2 (g) --> CO

2 + 2H

2O + Energy

Diagram:

Redox in MetabolismRedox reactions often occur in a chain.

This is what happens in metabolism. The electron(s) are moved to successively better oxidizing agents. (ex Electron Transport Chain)