Grade 12 Biochemistry

activation energy

the minimum amount of energy required to start a chemical reaction

activator

A protein that binds to DNA and stimulates transcription of a specific gene.

active site

the part of an enzyme or antibody where the chemical reaction occurs

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

allosteric inhibitor

causes a structural change in the enzyme that prevents the substrate from binding at the active site

allosteric sites

A region of the enzyme other then the active site to which a substrate can bind

alpha helix

A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure.

amino terminus

terminal amino

anabolic reaction

a type of chemical process that builds up simpler molecules into more complex ones

antiparallel

The opposite arrangement of the sugar-phosphate backbones in a DNA double helix.

beta-pleated sheet

One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds.

bond energy

the energy required to break a chemical bond and form neutral isolated atoms

bonding capacity

number of covalent bonds the atom can form (usually equals the amount of unpaired electrons required to complete the atom's outermost shell)

buffers

weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH

carboxyl terminus

terminal carboxyl

catabolic reactions

Complex molecules are broken down to simpler ones and energy is released.

chaperone proteins

help other proteins fold into their precise shapes

coenzymes

Metal ions or organic compounds that help enzymes.

cofactors

nonprotein helpers needed by enzymes

competitive inhibitors

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics

conformation

a symmetrical arrangement of the parts of a thing

disulfide bridge

A strong covalent bond formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer.

electronegativity

a measure of the ability of an atom in a chemical compound to attract electrons

endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.

energy

the capacity of a physical system to do work

entropy

A quantitative measure of disorder or randomness, symbolized by S.

enzyme-substrate complex

A temporary complex formed when an enzyme binds to its substrate molecule(s).

essential amino acids

Amino acids that are needed, but cannot be made by the body; they must be eaten in foods

ester linkage

A bond between a hydroxyl group and a carboxyl group

exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy.

feedback inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

free energy (Gibbs)

is the amount of energy available to do [chemical] work

functional groups

group of atoms that usually participate in chemical reactions in an organic molecule

globular proteins

These proteins are small spheres with little to no water inside. They have hydrophobic amino acids in the inside and hydrophilic R groups on the outside.

glycosidic proteins

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glycosidic linkages

Covalent bonds holding monosaccharides together, formulated by a condensation reaction; Uses H atom from hydroxyl of one sugar and OH from hydroxyl of another sugar.

hydrolysis reaction

a chemical reaction that breaks apart a larger molecule by adding a molecule of water

hydrophilic

having a strong affinity for water

hydrophobic

lacking affinity for water

immiscible

describes two or more liquids that do not mix into each other

induced-fit model

interactions between the substrate and the enzyme that change the shape of the enzyme

intermolecular bonds

Weak bonds that are held together by polarity or another weak force, present in hydrogen bonds.

intramolecular forces of attraction

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isomers

compounds with the same formula but different structure

kinetic energy

energy of motion

macromolecules

four main classes of large biological molecules (carbohydrates, lipids, proteins, nucleic acids)

metabolism

the organic processes (in a cell or organism) that are necessary for life

micelles

polar heads interact with water; nonpolar tails 'hide' inside (looks like little balls with the tails inside)

miscible

describes two or more liquids that are able to dissolve into each other in various proportions

neutralization reaction

a chemical reaction in which an acid and a base interact with the formation of a salt

noncompetitive inhibitors

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.

oligosaccharides

Sugars containing several simple sugars attached to one another using glycosydic linkages.

oxidation

the process of oxidizing

LEO GER

oxidizing agent

The electron acceptor in a redox reaction.

peptide bonds

The bonds connecting amino acids together to form polypeptide chains in protein synthesis.

phosphorylation

The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.

potential energy

stored energy

potential energy diagram

a diagram that shows the changes in potential energy that takes place during a chemical reaction

primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

redox reaction

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

reducing agent

The electron donor in a redox reaction.

reduction

any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen)

residue

matter that remains after something has been removed

secondary structure

The second level of protein structure; the regular local patterns of coils or folds of a polypeptide chain.

strand

a pattern forming a unity within a larger structural whole

strong acids

Completely ionized in aqueous solution

strong bases

dissociate completely into metal ions and hydroxide ions in aqueous solution

substrate

the substance acted upon by an enzyme or ferment

tertiary structure

The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain.

transition state

An unstable grouping of atoms that exists momentarily in the course of a reaction, when a system is highest in energy.

triglycerides

long term energy storage molecules formed during condensation synthesis between 3 fatty acids and one molecule of glycerol

valence electrons

electrons on the outermost energy level of an atom

van der Waals forces

a slight attraction that develops between the oppositely charged regions of nearby molecules

weak acids

acids that are weak electrolytes

weak bases

react with water to form the hydroxide ion and the conjugate acid of the base