Video Transcript
Complete the equation to demonstrate the process of deamination. Amino acids are converted into blank plus organic acid. (A) ATP, (B) carboxyl, (C) ammonia, (D) water, or (E) oxygen.
This question asks us about a very important function that occurs in the human liver:
the deamination of amino acids. To figure out the missing word in the statement in the question, let’s review some
key facts about a couple of the main 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. In the liver cells, amino groups are removed from these excess amino acids,
converting them into organic acids that can now be used by the body cells. This process is called deamination and is of interest to us in this question. Deamination also produces a highly toxic byproduct called ammonia. Ammonia is typically detoxified in the liver cells into a less harmful molecule
called urea, which can then be removed from the body as a part of urine.
Now we know the word that should fill in the blank in the statement and therefore the
correct answer to our question. Amino acids are converted into ammonia and organic acids, so the correct answer is
(C) ammonia.
