CH:2 - Biological Molecules Flashcards
(26 cards)
Macromolecule
A large molecule such as a polysaccharide, protein or nucleic acid.
Polymer
A giant molecule made from many similar repeating subunits joined together in a chain; the subunits are much smaller and simpler molecules
known as monomers; examples of biological polymers are polysaccharides, proteins and nucleic acids.
Monomer
A relatively simple molecule which is used as a basic building block for the synthesis of a polymer; many monomers are joined together by covalent bonds to make the polymer, usually
by condensation reactions; common examples
of monomers are monosaccharides, amino acids and nucleotides.
Monosaccharide
A molecule consisting of a single sugar unit and with the general formula (CH2O)n.
Condensation Reaction
A chemical reaction involving the joining together of two molecules by removal of a water molecule.
Hydrolysis
A chemical reaction in which a chemical bond is broken by the addition of a water molecule; commonly used to break down complex molecules into simpler molecules.
Disaccharide
A sugar molecule consisting of two monosaccharides joined together by a glycosidic bond.
Glycosidic bond
A C–O–C link between two sugar molecules, formed by a condensation reaction; it is a covalent bond.
Benedict’s test/reagent test
A test for the presence of reducing sugars; the unknown substance is heated with Benedict’s reagent, and a change from a clear blue solution to the production of a yellow, red or brown precipitate indicates the presence of reducing sugars such as glucose.
Polysaccharide
A polymer whose subunits are monosaccharides joined together by glycosidic bonds.
Glycogen
A polysaccharide made of many glucose molecules linked together, that acts as a glucose store in liver and muscle cells.
Cellulose
A polysaccharide made from beta-glucose
subunits; used as a strengthening material in plant cell walls.
Hydrogen Bond
A relatively weak bond formed by the attraction between a group with a small positive charge on a hydrogen atom (Hδ+) and another group carrying a small negative charge (δ−), e.g. between two –Oδ–Hδ+ groups.
Ester bond/ester linkage
A chemical bond, represented as –COO– , formed when an acid reacts with an alcohol.
Triglyceride
A type of lipid formed when three fatty acid molecules combine with glycerol, an alcohol with three hydroxyl (−OH) groups.
Peptide Bond
The covalent bond joining neighbouring amino acids together in proteins; it is a C–N link between two amino acid molecules, formed by a condensation reaction.
Polypeptide
A long chain of amino acids formed by condensation reactions between the individual amino acids; proteins are made of one or more polypeptide chains; see peptide bond.
The different structures of PROTEINS?
Primary structure: The sequence of amino acids
in a polypeptide or protein.
Secondary structure: The structure of a protein
molecule resulting from the regular coiling or
folding of the chain of amino acids (an α-helix or
β-pleated sheet).
Tertiary structure: The compact structure of
a protein molecule resulting from the three-dimensional coiling of the chain of amino acids.
Quaternary structure: The three-dimensional
arrangement of two or more polypeptides, or of a
polypeptide and a non-protein component such as haem-, in a protein molecule.
α-helix
A helical structure formed by a polypeptide chain, held in place by hydrogen bonds; an α-helix is an example of secondary structure in a protein.
β-pleated sheet
A loose, sheet-like structure formed by hydrogen bonding between parallel polypeptide chains; a β-pleated sheet is an example of secondary structure in a protein.
Haemoglobin
The red pigment found in red blood cells, whose molecules contain four iron atoms within a globular protein made up of four polypeptides; it combines reversibly with oxygen.
Globular Protein
A protein whose molecules are folded into a relatively spherical shape, often has physiological roles and is often water-soluble and metabolically active, e.g. insulin, haemoglobin and enzymes.
Sickle Cell Anaemia
A genetic disease caused by a faulty gene coding for haemoglobin, in which haemoglobin tends to precipitate when oxygen concentrations are low.
Collagen
The main structural protein of animals; known as ‘white fibres’, the fundamental unit of the fibre consists of three helical polypeptide chains wound around each other, forming a ‘triple helix’ with high tensile strength.
