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

The simplest amino acid is

  1. Proline

  2. Serine

  3. Glycine

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

Glycine is the simplest amino acid because its side chain is just a single hydrogen atom, making it the only achiral amino acid.

Multiple choice

Polypeptide backbone doesn't contain

  1. Side chains

  2. Peptide bond

  3. Nitrogen atom

  4. Asymmetric carbon atom
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The polypeptide backbone consists of the repeating N-Calpha-C sequence. The side chains (R-groups) are attached to the alpha-carbon but are not considered part of the backbone itself.

Multiple choice

In native state, amino acids occur as

  1. L-stereo isomers

  2. D-stereo isomers

  3. No isomerism seen

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

In biological systems, proteins are synthesized using only L-amino acids, which are the L-stereoisomers.

Multiple choice

Prosthetic group is

  1. Metal (like Zn++ or Mg++) attached to the protein part of an enzyme

  2. Protein part of an enzyme

  3. Organic molecule attached to protein part of an enzyme

  4. Complete enzyme molecule
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A prosthetic group is a non-protein organic molecule or metal ion that is tightly or covalently bound to an enzyme and is essential for its catalytic activity.

Multiple choice

Amino acid lacking an optically active α-carbon is

  1. Arginine

  2. Histidine

  3. Glutamic acid

  4. Glycine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Glycine has a hydrogen atom as its side chain. Since it has two identical substituents (two hydrogens) on the alpha-carbon, it is achiral and not optically active.

Multiple choice

Globular proteins are said to be in β-conformation, if

  1. they contain β strands only

  2. they contain α-helices interspersed with β-strands

  3. they are twisted in a left-handed helix instead of the usual right-handed one

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Globular proteins often contain complex secondary structures, including both alpha-helices and beta-strands. Beta-conformation refers to the presence of beta-sheets or strands within the protein structure.

Multiple choice

Denatured protein has a/an

  1. Folded polypeptide chain

  2. Unfolded polypeptide chain

  3. Polypeptide chain liked with disulphide bonds

  4. Polypeptide chain linked with weak covalent bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Denaturation is the process where a protein loses its native three-dimensional folded structure. This results in an unfolded polypeptide chain, rendering the protein biologically inactive.

Multiple choice

Interferons are anti _________ proteins.

  1. viral

  2. bacterial

  3. protozoan

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

Interferons are signaling proteins released by host cells in response to the presence of several viruses, acting as antiviral agents.