Grade 12 biology - The biochemical basis of life

Isotope

a form of an element that differs in its number of neutrons

radioisotope

A radioactive isotope of an element (The nuclei of some isotopes of an element are unstable and tend to break down, or decay, giving off particles of matter that can be detected as radioactivity. The decay process transforms an unstable, radioactive isotope)

orbital

a region of space that is occupied by electrons located around the nucleus of an atom

valence electron

an electron in the outermost energy level or shell of an atom

ionic bond

a bond that results from the attraction between two oppositely charged atoms or molecules

cation

an ion that has a positive charge

anion

an ion that has a negative charge

Electronegativity

the measure of an atoms attraction to shared electrons

polar covalent bond

a bond between two atoms, made up of unequally shared electrons

polarity

partial positive or negative charge at the ends of a molecule

intermolecular force

the force of attraction between two molecules

van der waals forces

very weak attractions between two molecules, or parts of molecules, when they are close together

hydrogen bond

the attractive force between a partially positively charged hydrogen atom and a partially negatively charged atom in another molecule

dehydration reaction

a chemical reaction in which subunits of a larger molecule are joined by the removal of water; also called a condensation reaction

hydrolysis reaction

a chemical reaction in which water is used as a reactant to split a larger molecule into smaller subunits

neutralization reaction

a reaction in which an acid and a base combine to create a salt and water

redox reaction

an electron transfer reaction

oxidation

a reaction in which a molecule loses electrons

reduction

a reaction in which a molecule gains electrons

96% of the weight in organic compounds in living organisms are composed primarily of:

carbon, hydrogen, nitrogen and oxygen

(They often occur as ions or in inorganic compounds) Most of the 4% of he weight inorganic compounds in living organisms are composed of:

Calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium

The rest of the elements (0.1%) required by organisms are called trace elements (A deficiency in any trace element can lead to health problems), examples are:

Iodine and iron

Specific heat

the amount of thermal energy required to raise the temperature of a given quantity of a substance by 1 C

hydrophilic molecules

polar or charged molecules that are strongly attracted to water

Auto ionization

The process in which a molecule spontaneously dissociates into ions

Buffer

A chemical that compensates for pH in a solution by accepting or donating H⁺ ions

Functional group

A group of atoms that affects the function of a molecule by participating in chemical reactions

Most functional groups are either:

Ionic or strongly polar (this makes them very attracted to other ionic or polar molecules, including water molecules)

Carbohydrate

A biomolecule that consists of carbon, oxygen and hydrogen

Monosaccharide

The simplest form of carbohydrate, consisting of a simple sugar unit; a building block for more complex carbohydrates

Isomer

A molecule that has the same composition as another, but a different arrangement of atoms

Disaccharide

A carbohydrate molecule that is made from two monosaccharide units that are joined together by a dehydration synthesis reaction

Glycosidic bond

A bond between two monosaccharides

Complex carbohydrate

A molecule that is composed of hundreds to thousands of monosaccharides linked together; an essential part of nutrition and a valuable energy source

Polysaccharide molecule

A molecule that contains many linked monosaccharides

Polymerization

A process in which small subunits are linked to form a large molecule

Monomer

A small molecule that can bind chemically to other molecules

Polymer

A large molecule that is formed when monomers link together chemically in a chain

Lipid

A non polar compound that is made mostly of carbon and hydrogen

Fatty acid

A molecule that consists of a carboxyl group and a hydrocarbon chain

Triglyceride

A fat; three fatty acid chains linked to a glycerol molecule

Saturated fat

A lipid that is composed of saturated fatty acids with single bonds in their hydrocarbon chain

Unsaturated fat (oils)

A lipid that is composed of unsaturated fatty acids with double bonds in their hydrocarbon chain (become less fluid as their chains grow longer)

Phospholipids

A lipid that consists of two fatty acids and a phosphate group bound to glycerol

Most plant fats are

Unsaturated fats

Diets rich in saturated fats can lead to

Heart disease

A fat is

A lipid that is made from two types of molecule: fatty acid and a glycerol molecule

Steroid

A lipid that is composed of four carbon rings

wax

A lipid that is formed when long fatty acid chains are joined to alcohols or carbon rings

Protein

A large molecule that consists of many amino acid subunits that are joined together by peptide bonds folded into a specific three-dimensional shape

Nucleic acid

A blueprint for proteins that are synthesized in cells; stores hereditary information

Amino acid

A molecule that contains a carboxyl group and an amino group; serves as the monomer subunits or proteins

Denaturation

The loss of both the structure and function of a protein

Nucleotide

the building block of nucleic acids; consists of a 5-carbon sugar, a nitrogenous base, and one to three phosphate groups

Pyrimidine

Single organic rings (Uracil, thymine, cytosine)

Purines

Two ringed organic structures (adenine and guanine)

Phosphodiester bond

A link that is formed between nucleotides by a phosphate bridge

Antiparallel

Oriented in opposite directions

Enzyme

A biological catalyst, usually protein, that speeds up a chemical reaction (if even one enzyme is missing or defective, the results can be disastrous)

Substrate

A substance that is recognized by and binds to an enzyme

Active site

A pocket or groove in an enzyme that binds its substrate

Induced-fit model

A model of enzyme activity that describes how an enzyme changes shape to better accommodate a substrate

Cofactor

A non-protein group that binds to an enzyme and is essential for catalytic activity

Coenzyme

An organic molecule that acts as a cofactor of an enzyme

Competitive inhibition

A situation in which a competitor substance binds to a normal substrate binding site to block enzyme activity

Non competitive inhibition

A situation in which molecules bind to an enzyme at a site that is not the active site, thus blocking enzyme activity

allosteric site

A binding site on an enzyme that binds regulatory molecules

Allosteric regulation

The regulation of one site of a protein by binding to another site on the same protein

feedback inhibition

The regulation of a pathway by one of the products of this pathway