Biology · Chemistry

Biomolecules and Enzymes

1,501 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice

A zwitter ion is one which

  1. is positively charged

  2. is negatively charged

  3. is both (1) and (2)

  4. is carbanion

  5. is carbocation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ans : 3.

Multiple choice

_____ is the basic building block of protein.

  1. Hydrochloric acid

  2. Phosphoric acid

  3. Amino acid

  4. Nitric acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Amino acids are the organic compounds that serve as the fundamental building blocks (monomers) of proteins.

Multiple choice

What is a peptidoglycan?

  1. Single large polymer

  2. A polymer made up of amino acids and sugar

  3. Collection of a large number of polymers

  4. Both (A) and (C)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Peptidoglycan is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall.

Multiple choice

Which of the following statements characterises a peptide immunogen?

  1. It can mimic a part of a discontinuous epitope.

  2. It adopts a single rigid structure in solution.

  3. It can elicit potent antibody responses in the absence of T-cell help.

  4. It can be used to stimulate B-cell, but not T-cell responses.

  5. Lack of contact residues capable of interacting with the antigen receptor on the relevant lymphocytes.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Although a single peptide sequence, being a linear array of amino acids, by definition cannot fully represent a discontinuous epitope, it can comprise a part of such an epitope. However, because the epitope is incomplete, the peptide would probably only generate antibodies that have a relatively low affinity for the native antigen.

Multiple choice

Naturally occurring macromolecules like proteins, starch etc are very stable and behaves as:

  1. lyophobic colloids

  2. multimolecular colloids

  3. macromolecular colloids

  4. associated colloids
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Macromolecular colloidal particles are formed when on dissolution in a suitable solvent, the macromolecules have sizes which are in the colloidal range. Naturally occurring macromolecules are starch, proteins and cellulose. Man made macromolecules are polymers such as polyethylene, nylon and polystyrene. These colloids are quite stable and resemble true solutions in many respects.

Multiple choice

The molecules of gelatine, starch, & proteins in organic solvents are the example of:

  1. lyophilic colloids

  2. lyophobic colloids

  3. multimolecular colloids

  4. macromolecular colloids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In this type of colloids sols, the dispersed phase has great attraction for the dispersion medium. In such colloids, the dispersed phase does not precipitate easily and the sols are quite stable. If the dispersion medium is separated from the dispersed phase, the sol can be reconstituted by simply remixing with the dispersion medium. Hence, these sols are called reversible sols. Examples of lyophilic sols include sols of gum, gelatine, starch, proteins and certain polymers in organic solvents.

Multiple choice

Immunoproteasome is a protease abundant in immune cells. Which of the following statements does not characterises the immunoproteasome?

  1. It is generated in response to interferon-gamma stimulation.

  2. It contains the nonpolymorphic MECL1 subunit.

  3. It contains the polymorphic LMP7 subunit.

  4. Ten per cent of the peptides generated are 8–9 residues in length.

  5. It exhibits both chymotrypsin-like and trypsin-like activities.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

About ten per cent of the peptides generated by the housekeeping proteasome are 8–9 residues in length, but the immunoproteasome is thought to be specialized to produce a greater proportion of peptides of this length which is optimal for insertion into the MHC class I groove.