1.1 Proteins have many functions,
both inside and outside the cells
of living organisms. Proteins, as
enzymes, are now used widely in
the home and in industry.
1.1.1 Protein molecules are made up of long chains of amino acids. These
long chains are folded to produce a specific shape that enables other
molecules to fit into the protein. Proteins act as structural components
of tissues such as muscles, hormones, antibodies and catalysts.
188.8.131.52 Catalysts increase the rate of chemical reactions. Biological
catalysts are called enzymes. Enzymes are proteins.
2 B2.5.2 Enzymes
2.1 The shape of an enzyme is vital for the enzyme's function. High temperatures change the shape.
2.1.1 Different enzymes work best at different pH values.
184.108.40.206 Some enzymes work outside the body cells. The
digestive enzymes are produced by specialised cells in
glands and in the lining of the gut. The enzymes then
pass out of the cells into the gut where they come into
contact with food molecules. They catalyse the
breakdown of large molecules into smaller molecules.
220.127.116.11.1 The enzyme amylase is
produced in the salivary
glands, the pancreas and the
small intestine. This enzyme
catalyses the breakdown of
starch into sugars in the
mouth and small intestine.
18.104.22.168.1.1 Protease enzymes are produced by the stomach, the
pancreas and the small intestine. These enzymes
catalyse the breakdown of proteins into amino acids in
the stomach and the small intestine.
22.214.171.124.1.1.1 Lipase enzymes are produced by the pancreas and
small intestine. These enzymes catalyse the
breakdown of lipids (fats and oils) into fatty acids and
glycerol in the small intestine.
126.96.36.199.188.8.131.52 The stomach also produces hydrochloric
acid. The enzymes in the stomach work most
effectively in these acid conditions.
184.108.40.206.220.127.116.11.1 The liver produces bile, which is stored in the
gall bladder before being released into the
small intestine. Bile neutralises the acid that
was added to food in the stomach. This
provides alkaline conditions in which enzymes
in the small intestine work most effectively.
18.104.22.168.22.214.171.124.1.1 Some microorganisms produce
enzymes that pass out of the cells.
These enzymes have many uses in
the home and in industry.
126.96.36.199.188.8.131.52.1.1.1 At home, biological detergents may contain protein-digesting and
fat-digesting enzymes (proteases and lipases) and these detergents
are more effective at low temperatures than other types of detergents.
184.108.40.206.220.127.116.11.18.104.22.168 In industry, proteases are used to
'pre-digest' the protein in some baby foods,
carbohydrases are used to convert starch
into sugar syrup and isomerase is used to
convert glucose syrup into fructose syrup,
which is much sweeter and therefore can be
used in smaller quantities in slimming foods.
22.214.171.124.126.96.36.199.188.8.131.52.1 In industry, enzymes are used to bring about reactions at normal
temperatures and pressures that would otherwise require expensive,
energy-demanding equipment. However, most enzymes are denatured
at high temperatures and many are costly to produce.