Proteins
To make a protein, amino acids are linked together in a long
chain. The chain is then bundled into to a three-dimensional
structure, like a tangled ball of yarn. Although there are
hundreds of different amino acids, only 21 are used in animal
proteins.
Proteins are the essential building blocks of all tissues
and organs of the body including:
- cartilage, tendons and ligaments (collagen and
elastin),
- the element of muscles that contract (actin and
myosin),
- skin, hair and nails (keratin),
- blood proteins (haemoglobin, transferrin, albumin and
globulins),
- enzymes,
- hormones,
- antibodies.
Proteins are often described as the 'backbone' of cells
because they have a structural role in all cell walls. Proteins
are required for all tissue growth, replenishment and
repair.
If there is more protein available than necessary for
building blocks, proteins may also be used as a source of
dietary energy.