IMAT 2013 Q33 [Amino Acids]

Which one of the following does not contain amino acids?

A. Cell membranes
B. Amylose
C. Viruses
D. Enzymes
E. Antibodies

The answer to this question is choice B, Amylose.

Why is amylose the correct answer? You will have to be aware of its structure to know why amylose does not contain amino acids. Amyslose is made up of (1,4) glucose units that are bound to each other via glycosidic bonds. It’s structure being pure glucose makes it the correct answer, as it does not contain any amino acids.

Let’s rule out the other choices that contain amino acids and proteins:

  • Cell membranes, enzymes, and antibodies: All of these three either contain proteins or are made up of proteins. Cell membranes for example, are indeed made up of a phospholipid bilayer, but it contains transmembrane proteins and peripheral proteins that play an important role in terms of interacting with ions and molecules etc. Enzymes and antibodies are both made of long polypeptide chains. Thus, the presence of proteins in these 3 choices eliminates them from your considerations.
  • Viruses: viruses are capable of producing proteins that are essential especially as structural components such as their viral envelope and capsids. These viral proteins not only serve their protective function, but also play a role in attachment and entry into host cells as a form of evasion to host defenses. Thus, viral proteins are an important part of the virulence of viruses. The presence of proteins therefore eliminates this as well among your considerations.

Thus, the only choice that does not contain amino acids (and subsequently proteins) is choice B, amylose.