Glossary

adenosine triphosphate (ATP)

Coenzyme found in all lifeforms, that is important for metabolism as an energy molecule.

adipocytes

Lipid storage cells.

alpha (α)-helix

Type of secondary protein structure formed by folding the polypeptide into a helix shape with hydrogen bonds stabilising the structure.

amino acids

A protein’s monomer that has a central carbon or alpha carbon to which an amino group, a carboxyl group, a hydrogen, and an R group or side chain is attached; the R group is different for all 20 common amino acids.

anions

Negatively charged ion.

arthropods

Diverse group of invertebrate animals that have an exoskeleton (a hard, external covering), a segmented body, and jointed appendages. They include insects, spiders, centipedes, and crabs.

atom

Smallest part of a substance that uniquely defines a chemical element and cannot be broken down while retaining element properties.

atomic number

Number of protons in a nucleus.

beta (β)-pleated sheet

Covalently linked amino acid chains linked to adjacent chains by hydrogen bonds to form an accordion-like sheet.

carbohydrates

Biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells and form arthropods’ cellular exoskeleton.

catalysts

Substance that increases the rate of a chemical reaction by lowering the energy barrier of the reaction’s transition state, but remains unchanged and un-consumed at the end of the reaction.

cations

Positively charged ion.

cholesterol

Fat-like, waxy steroid mainly synthesised in the liver and is an important precursor for many steroid hormones, vitamins E and K, and bile salts.

cohesion

Like molecules sticking together.

covalent bond

Equal sharing of one or more electron pairs by two or more atoms.

disaccharides

Two sugar monomers that a glycosidic bond links.

electron

Subatomic particle with a negative charge that are bound or unbound to all atoms.

electron transfer

Movement of an electron from one element to another.

elements

Made of atoms and is a substance that cannot be degraded or altered chemically into another substance.

enzymes

Catalyst in a biochemical reaction that is usually a complex or conjugated protein.

essential fatty acids

Fatty acids that are required for physiological processes and cannot be synthesised by the body.

evaporation

Process of turning from liquid into vapour.

exoskeleton

External hard shell or rigid structure that supports and protects an animal’s body.

hormones

Secretion of an endocrine organ that travels via the bloodstream or lymphatics to induce a response in target cells or tissues in another part of the body.

hydrogen bonds

Attachment of a covalently bonded hydrogen atom to another atom.

hydrophilic

Describes a substance or structure attracted to water.

hydrophobic

Property of a molecule to be repelled by, or not having an affinity for, water.

ionic bonds

Attachment due to electron transfer from one atom or molecule to another atom or molecule. Also known as electrovalent bond.

ions

Positively or negatively charged atom or molecule.

isotopes

Different form of the same element that has the same number of protons but a different number of neutrons.

lipid

Macromolecule that is nonpolar and insoluble in water.

low-density lipoprotein (LDL)

Circulating fat that transports cholesterol. Commonly known as ‘bad’ cholesterol.

mass number

Sum of the number of protons and neutrons in an element. Also known as atomic mass.

matter

Composed of elements and is something that occupies space and has mass.

molecules

Two or more atoms held together by chemical bonds that make up the smallest fundamental unit of a chemical compound.

monosaccharides

Single unit or monomer of carbohydrates.

neutrons

Subatomic particle with no electrical charge, present in the nuclei of atoms except hydrogen, and slightly higher mass as a proton.

nonpolar

Symmetric distribution of electrical charge, resulting in no areas of positive or negative charge.

oils

Hydrophobic and lipophilic, nonpolar, viscous fluid.

peptide bond

Bond formed between two amino acids by a dehydration reaction.

phospholipids

Membranes’ major constituent; comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone.

polypeptides

Long chain of amino acids that peptide bonds link.

polysaccharide

Membranes’ major constituent; comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone.

primary structure

Polypeptide chain sequence of amino acids.

proteins

Biological macromolecule comprised of one or more amino acid chains.

proton

Subatomic particle with positive electrical charge, present in the nuclei of all atoms and slightly lower mass of a neutron.

quarks

Subatomic particles carrying fraction of an electric charge.

saturated fatty acids

Long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximised.

secondary structure

Structure comprised of arrangements of adjacent polypeptide chains amino acid residues.

solvent

Molecule, typically a liquid, that can dissolve a solid.

steroids

Type of lipid comprised of four fused hydrocarbon rings forming a planar structure.

subunits

Assembly of multiple polypeptide chains or protein molecules.

surface tension

Cohesive nature of liquid in which it acts as a stretched elastic membrane, allowing resistance to external force.

temperature

Objective measure of hotness and coldness.

tertiary structure

Polypeptide three-dimensional structure that allows functionality.

triglycerides

Fat molecule; consists of three fatty acids linked to a glycerol molecule. Also known as Triacylglycerol.

unsaturated fatty acid

Long-chain hydrocarbon that has one or more double bonds in the hydrocarbon chain.

van der Waals interactions

Weak attractive forces with nonspecific, nondirectional attraction of outer electron clouds of adjacent atoms.