An important function the liver has in the human body is to carry out the deamination
of amino acids. What happens to an amino acid undergoing deamination? (A) It has an amino group added. (B) It has an amino group removed. (C) It is converted into ammonia. (D) It reacts with ammonia to form carbon dioxide. Or (E) it has a carboxyl group removed.
This question asks us about a very important function that occurs in the human liver:
the deamination of amino acids. To figure out the answer, let’s review some key facts about a couple of the many
functions of the liver: detoxification and excretion. Proteins in the food that we eat are broken down in the human digestive system into
smaller units called amino acids. You might recall that the basic structure of an amino acid has a central carbon atom,
the 𝛼 carbon, that can form four bonds. One bond is formed with an amino group, NH2, one with a carboxyl group, COOH, one
with a hydrogen, and one with a side chain that is variable depending on the amino
acid, often represented as R.
Not all of the amino acids that are produced from the breakdown of proteins can be
stored. And they need to be broken down by the liver into molecules that can be used by or
excreted from the body. To do this, the liver cells carry out deamination, which involves the amino groups
being removed from these excess amino acids. This converts them into organic acids that can now be used by the body cells. Deamination also produces a highly toxic byproduct called ammonia, which is typically
detoxified in the liver cells, forming a less harmful molecule called urea, which
can be removed from the body as a part of urine.
After reviewing the structure of amino acids and the process of deamination in the
liver, we have enough information to determine what happens to an amino acid
undergoing deamination and therefore answer this question correctly. The correct answer is (B). It has an amino group removed.