BIO 1140 - Cell Metabolism

capacity to cause change, especially to do work (to move matter against an opposing force). - Different forms of energy are interconvertible

energy associated with the relative motion of objects

energy available in molecules for release in a chemical reaction (= potential energy)

kinetic energy due to the random motion of atoms and molecules (= heat)

energy that matter possesses as a result of its location or spatial arrangement

thetotal amountof energyin theuniversemustalways bethesame

Light Energy - Universal source is the sun - Used in photosynthesis - the radiant energy of sunlight sustains all life, with few exceptions

All animals live on energy stored in the chemical bonds of organic molecules (from food) - Animals eat plants or eat other animals that eat plants. - Plants obtain their energy directly from sunlight.

Solar energy enters the living world through photosynthesis in plants

Photosynthesis is a process that converts the electromagnetic energy in sunlight into chemical-bond energy in organic molecules.

Cellular Respiration is a process that extracts energy from organic molecules (food) by gradual oxidation.

The addition of oxidizing agent - Takes away electrons - Most common agent is oxygen

The converse reaction, called reduction, involves the addition of electrons to an atom.

Living cells create and maintain order in a universe that is tending always toward greater disorder.

Measure of system’s disorder - Requires constant energy for cell function + organization - creates more favourable environments for cell systems - Order is necessary for survival

The increased order inside the cell is accompanied by increased disorder in the cells’ surroundings - Disorder increases when useful energy that could be harnessed to do work (free energy) is dissipated as heat

amount of energy available in a molecule to do work in a system when the temperature and pressure are uniform - measured in in kcal/mole. - can also be expressed in joules (1 cal = 4.184 joules

stored in the bonds between individual atoms of a molecule

causes vibration, rotation and movement of the molecule through space

• The reaction can decrease the amount of order in the cell • Changes of bond energy of the reacting molecules can cause heat to be released, which disorders the environment around the cell

The free-energy change for a reaction determines whether it can occur

measures theamount ofdisordercreated in the universewhen areactioninvolving these moleculestakesplace - the change inorder inside the cell and the change in order of the surroundings

A chemical reaction that occurs spontaneously must have a negative ΔG - The disorder of the universe can only increase. - ΔG is negative if the disorder of the universe (reaction plus surroundings) increases - Exergonic Reaction - Favourable

the rates of the forward and reverse reactions are equal - Reactions will eventually reach a chemical equilibrium - ΔG = 0, so the reaction will not proceed forward or backward