Grade 12 biology - An introduction to Metabolism

Metabolism

The sum of all chemical reactions in a cell or organism

Kinetic energy

The energy of motion

Potential energy

The stored energy that an object possesses as a result of its position relative to other objects or to its internal structure

First law of thermodynamics

Principle that states that energy can be transferred or transformed, but it cannot be created or destroyed

Bond Energy

The minimum amount of energy that is required to break a particular type of bond; measured in kj/mol of bonds

Mole

The number (approximately 6.022 × 10²³.) of atoms or molecules whose mass in grams is equal to the atomic mass of one such particle in atomic mass units; one carbon atom has a mass of 12 AU, and therefore, one mole of carbon atoms has a mass of 12 g

Activation energy (E_a.

The minimum amount of energy that chemical reactants must absorb to start a reaction

Transition state

A temporary condition during a chemical reaction in which the bonds in the reactants are breaking and the bonds in the products are forming

Exothermic reaction

A chemical reaction in which energy is released, leaning the products with less chemical potential energy than the reactants

Endothermic reaction

A chemical reaction in which energy is absorbed, giving the products more chemical potential energy than the reactants

Second law of thermodynamics

Principle that states that every time energy is converted to another form, some of the energy becomes unusable

Entropy

A measurement of disorder in a system

Spontaneous change

A change that will, once begun, continue on its own under a given set of conditions; does not require a continuous supply of energy

Free energy

Energy that can do useful work; also called Gibbs free energy

Exergonic reaction

A chemical reaction that releases free energy; the products have less free energy than the reactants

Endergonic reaction

A chemical reaction that absorbs free energy; the products have more free energy than the reactants

Energy coupling

The transfer of energy from one reaction to another in order to drive the second reaction

Catabolic pathway

A pathway in which energy is released and complex molecules are broken into simple molecules

Anabolic pathway

A pathway in which energy is supplied to build complex molecules from simple molecules

Mechanical work (ATP)

-beating of cilia or movement of flagella

-contraction of muscle fibres

-movement of chromosomes during mitosis/meiosis

Transport work (ATP)

-process of pumping substances across membranes against their concentration gradient

Chemical work (ATP)

-process of supplying chemical potential energy for non-spontaneous, endergonic reactions, including protein synthesis

phosphorylation

the transfer of a phosphate group, usually from ATP, to another molecule

Adenosine triphosphate consists of

-a nitrogen base called adenine

-five carbon sugar named ribose

-a chain oof three phosphate groups

ATP cycle

the cyclic and ongoing breakdown and re-synthesis of ATP

Enzymes DO

-lower the activation energy of a reaction

-increase the rate of a spontaneous (exergonic) reaction

Enzymes DO NOT

• alter the products of a reaction

• supply free energy to a reaction

• make an endergonic reaction proceed spontaneously

dehydrogenase

an enzyme that oxidizes a substrate and transfers hydrogen ions to an acceptor

NADH

the reduced form of the coenzyme nicotinamide adenine dinucleotide