Protein
Polymer consisting of one or more polypeptides
Formed by dehydration
3D under normal conditions
[!abstract] Globular
(Of a protein) spherical
[!abstract] Denaturation / renaturation
Denaturation: loss of 3D structure at high temperature or extreme pH
Renaturation: regain of 3D structure at low temperature or normal pH
Types
Grouped by function
Hormonal
Coordination of the organism's activities
[!example] Insulin: regulate blood sugar
Receptor
Response to chemical stimuli
[!example] Receptors in the membrane of a nerve cell detect signalling molecules from other nerve cells.
Enzymatic
[!example] Digestive enzymes catalyst the hydrolysis of polysaccharides.
Defensive
Protection against disease
[!example] Antibodies inactivate and help destroy viruses and bacteria.
Contractile and motor
Movement
[!example] Actin and myosin: contraction of muscles
Structural
Structural support
[!example]
- Keratin: protein of hair, horns and feathers
- Silk fibre: cocoon and web
- Collagen and elastin proteins: animal connective tissues
Storage
Storage of amino acids
[!example]
- Casein: protein of milk
- Ovalbumin: protein of egg white
Transport
Transport of substances
[!example] Hemoglobin: iron-containing protein in blood that transports oxygen
Ajitani Hifumi