Chapter 6 McGraw Hill Bio

Energy

the capacity to do work

Kinetic energy

the energy of motion

Potential energy

stored energy

calorie

the heat required to raised the temperature of water one degree celsius (C)

joule

equals .239 cal; energy unit often used in physics

photosynthesis

the process in which energy is absorbed from the sunlight and used to combine H2O and and CO2 to form sugars, in doing so it converts Carbon from an inorganic to an organic form

oxidation

loses an electron

reduction

gains an electron

Thermodynamics

the branch of chemistry concerned with energy changes

First Law of Therrmodynamics

states that energy can not be created or destroyed, it can only be converted from one form to another

heat

a measure of the random motion of molecules (and therefore a measure of one form of kinetic energy

Second Law of Thermodynamics

states that disorder in the universe--entropy, is continuously increasing

free energy

the energy that is available to do work in any system

G (Gibbs free energy)

in a molecule within a cell where pressure and volume are usually constant. the free energy is denoted by-... which stands for-

enthalpy

the total energy contained in a molecules chemical bonds (designated by H)

Kelvin, Entropy

In the equation G = H -TS where G is defined as free energy and H is defined as enthalpy. What do T and S stand for

endergonic

any reaction that requires an input of energy resulting in positive G (which means H is greater and S is lower)

exergonic

any reaction that releases excess free energy as heat resulting in negative G (tend to proceed spontaneously)

activation energy

the extra energy needed to destabalize existing chemical bonds and initiate a chemical reaction

ATP

the chief currency for all cells is this nucleotide.

ADP

a molecule that started as ATP, but the outermost high energy phosphate bond has been hydrolized

catalysis

the process of influencing chemical bonds in a way that lowers the activation energy needed to initiate a reaction

enzymes

the agents that carry out most of the catalysis in living organisms

substrates

the molecules that will undergo a reaction

active sites

the locations in which substrates bind to enzymes

multienzyme complexes

several enzymes catalyzing different steps of a sequence of reactions associated with another in noncovalently bonded assemblies

cofactors

chemical components that assist enzymes

coenzyme

a cofactor that is a nonprotein organic molecule, they shuttle energy in the form of Hydrogen atoms from one enzyme to another in a cell

optimum temperature

the temperature at which an enzyme-catalyzed reaction operates most efficiently

inhibitor

a substance that binds to an enzyme and decreases its activity

competitive inhibitors

compete with the substrate for the same active site, occupying the active site, in turn preventing substrates from binding

noncompetitive inhibitors

bind to the enzyme in a location other that the active site, changing the shape of the enzyme thus disabling its ability to bind to the substrate

allosteric sites

"on/off" chemical switches on an enzyme

allosteric inhibitor

substance that binds to an allosteric site and reduces enzyme activity

allosteric activator

binds to allosteric sites to keep an enzyme in its active configuration

metabolism

the total of all chemical reactions carried out by an organism.

anabolism

the metabolic chemical reactions that expend energy to build up molecules

catabolism

reactions that harvest energy by breaking down molecules

biochemical pathways

metabolic reactions occuring in pathways where the product of one reaction becomes the substrate for the next; the organizational units of metabolism

feedback inhibition

the mode of regulation in which the end-product of the pathway binds to an allosteric sithe on the enzyme that catalyzes the first reaction on the pathway