Protein
Large polymers comprised of long chains of amino acids
Amino acids
Monomers that make up the protein polymers. All amino acids have the same basic structure and the R group is the only part that varies.
Peptide bonds
Covalent bonds that join two amino acids together
Polypeptide
Linear chain of amino acids
Secondary structure
Caused by hydrogen bonds forming between the =O on the carboxyl group and -H from the amino group
Secondary structure twist
Twist the chain into an alpha-helix OR into a beta pleated sheet.
Secondary structure uses
Give rise to strong, fibrous proteins. Keratin in wool and collagen in skin and blood vessels
Primary structure
Sequence of amino acids in a polypeptide chain, and joined together by peptide bonds
Tertiary structure
Formed when one polypeptide molecule twists and folds in on itself - only happens in a-helix. Makes globular proteins.
Tertiary shape maintained
Hydrogen bonds, ionic bonds, disulfate bridges and hydrophobic interactions
Ionic
Bonds that are formed from charged variable groups and can interact with water, helps a protein to dissolve
Disulfide bridge
Bonds are formed from variable groups containing sulfur atoms - two of these bonds together to form disulfide bridge. These are covalent bonds that are strong and more difficult to break.
Hydrogen
Bonds between polar variable groups
Hydrophobic interactions
Take place when the variable groups are non-polar. They are repelled by water and are usually found on the inside of the protein; a protein rich in non-polar side groups will be less soluble in water
Order of strength
Peptide bond (Covalent), Disulphide bond (covalent), Ionic bond, Hydrogen bond, Hydrophobic interactions
Metabolic globular functions
Enzymes (active sites to bind to a substrate), antibodies (sites for binding to antigens) and Hormones (sites for binding to specific receptors)
Quaternary structure
Involves linking together of two or more polypeptide chains, each of the polypeptide chains has a primary, secondary and sometimes tertiary structure. They have a non-protein group.
Fibrous proteins
Long thin molecules that are insoluble in water, therefore they have structural functions. Collagen is an example - it provides strength and toughness needed in tensions. Hydrogen bonds hold the three chains together
Globular protein
Compact spherical molecule, soluble, and functions include: enzymes, haemoglobin, antibodies, plasma, proteins and hormones
Fibrous
Little or no tertiary structure, long parallel polypeptide chains, cross linkages at intervals, long fibres and sheets formed, mostly insoluble and most have a structural role
Keratin
In hair and outer layer of skin
Collagen
In connective tissue
Globular
A complex tertiary structure, folded into a spherical/globular shape, usually soluble in water, some have a quarternary structure and has a role in metabolic reactions