Download B1 You and Your Genes: Spot the mistakes

B2: Enzymes Spot the mistakes!
Structure of digestive system
Food will first enter the mouth where it will be chemically digested by
the teeth into smaller pieces allowing there to be a smaller surface area
for the enzyme amylase to work on. Amylase breaks down starch into
maltose ( and then into glucose ) and is produced by the pituitary glands.
Food passes by peristalsis (waves of muscle contractions) into the
duodenum and form there into the stomach. The stomach churns the food
and produces sulphuric acid which breaks down protein molecules into
fatty acids. The food then passes into the small intestine where
absorption takes place. Absorption is the breakdown of large molecules
into smaller molecules. Finally the food passes into the large intestine
where water is absorbed into the bladder.
Enzyme structure
Enzymes are sometimes also called biological catalysts. They are made of
carbohydrate molecules and fold up in a particular way to produce an
inactive site. The molecule (such as starch) which they break down is
called a substance. All enzymes are specific meaning that they will only
break down (absorb) one type of molecule. E.g amylase will only break
down starch into glucose. Enzymes can be damaged by high temperatures
– we called this saturated.
Effect of temperature and pH on reaction rate
As the temperature of a reaction increases the rate increases. This is
because the molecules involved ( the enzyme and pass rate) move more
slowly and collide less often. This only occurs up a certain temperature
however (called the optimum). If the temperature increases too much
then the structure of the enzyme’s active site will alter and the
substrate will fit in. That is why it is important for our bodies to maintain
a constant temperature (around 45 degrees C.) pH can also affect the
rate of reactions involving enzymes. Most enzymes prefer pH 11 (neutral)
however some enzymes work better at low pH (acidic) such as pepsin
found in the small intestine.
Making use of enzymes
For years now we have been able to use detergents to help us wash our
dishes and our clothes. Biological washing powders take advantage of
using enzymes because it means we can wash clothes at higher
temperatures. The biological washing powder contains digestive enzymes
such as amylase which breaks fat down into fatty acids and glycerol and
proteases which break proteins down into glucose.
Baby foods contain proteases which pre-digest some of the food so that
amino acids are available to the babies sooner and it can be used in the
production of fuels and corn syrup.