Video Transcript
Which of the following tables
correctly summarizes the functions of amylase and lipase in the digestive
system? (A) Amylase, to catalyze the
hydrolysis of carbohydrates into smaller sugars; lipase, to catalyze the hydrolysis
of fats into glycerol and fatty acid molecules. (B) Amylase, to catalyze the
hydrolysis of fats into glycerol and fatty acid molecules; lipase, to catalyze the
hydrolysis of carbohydrates into smaller sugars. (C) Amylase, to catalyze the
hydrolysis of proteins into amino acids; lipase, to catalyze the hydrolysis of fats
into glycerol and fatty acid molecules. Or (D) Amylase, to catalyze the
hydrolysis of ATP into ADP and inorganic phosphate; lipase, to catalyze the
hydrolysis of proteins into amino acids.
This question asks us to determine
the functions of two enzymes that are involved in the human digestive system:
amylase and lipase. Let’s review where these enzymes
are located in addition to the reactions they catalyze to aid in digestion.
Digestion begins in the mouth as
soon as food is placed into it. Amylase, which is found in saliva,
breaks down large carbohydrates into smaller, more useful sugars. This process, and similar reactions
that occur in the digestive system which break down large molecules into smaller
ones, is called hydrolysis as it requires the addition of a water molecule to split
up these larger molecules into their smaller subunits.
Food passes from the mouth down the
esophagus to the stomach where a different type of enzyme will be acting. A protease enzyme called pepsin
primarily acts in the stomach to break down proteins into smaller polypeptides. This is easy to remember, as
pepsin, proteins, and polypeptides all begin with the letter P. Food then passes from the stomach
and into the small intestine. Enzymes that break down
carbohydrates and polypeptides also act in the small intestine, in addition to a
different group of molecules called lipases, which break down lipids, which are
sometimes referred to as fats, into fatty acids and glycerol molecules.
Now that we have reviewed some of
the main enzymes involved in the digestive system, we can take another look at the
question. As we know that amylase breaks down
large carbohydrates into smaller sugars and lipase breaks down lipids, or fats, into
fatty acids and glycerol molecules, the correct table summarizing the action of
these two enzymes is in answer option (A). The function of amylase enzymes is
to catalyze the hydrolysis of carbohydrates into smaller sugars, and the function of
lipase enzymes is to catalyze the hydrolysis of fats into glycerol and fatty acid
molecules.
