Biology · Chemistry

Biomolecules and Enzymes

1,432 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

What does the secondary structure of proteins mean?

  1. Linear sequence of amino acids belonging to a peptide chain

  2. Folding of linear polypeptide chain into specialised coiled structure

  3. The arrangement and interrelationship of twisted chains into specific loops and bends

  4. Presence of more than one polypeptide chain

  5. Integration of a prosthetic group in the polypeptide chain

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 
 

Multiple choice

What is the structure of haemoglobin?

  1. Primary

  2. Helical

  3. Tertiary

  4. Quaternary

  5. Amorphous

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Due to the presence of two polypeptide chains, hemoglobin has a quaternary structure which is a characteristic of many multi-subunit globular proteins.

 
 

Multiple choice

Antibody is formed by:

  1. protein

  2. carbohydrate

  3. nucleic acid

  4. lipid

  5. vitamin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Antibodies are glycoprotein molecules called immunoglobulins produced by plasma cells. They are composed of amino acid chains arranged in a characteristic Y-shape that specifically bind to antigens.

Multiple choice

Which of the following is not an example of simple protein?

  1. Albumin

  2. Globulin

  3. Glutelin

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

Casein is a phosphoprotein, not a simple protein. Simple proteins (albumins, globulins, glutelins) yield only amino acids on hydrolysis. Casein contains phosphate groups, making it a conjugated protein. This distinction is based on chemical composition after hydrolysis.

Multiple choice

Which of the following is not protein?

  1. Enzyme

  2. Apoenzyme

  3. Coenzyme

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

Coenzymes are small organic non-protein molecules that assist enzymes in catalyzing reactions. Enzymes, apoenzymes (protein part of enzyme), and isoenzymes (different forms of the same enzyme) are all proteins. Only coenzymes are not proteins.

Multiple choice

The proteins, which are different in peptide sequence but have a similar structure in the process of evolution are said to be

  1. convergent

  2. divergent

  3. opportunistic

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

Proteins that are different in peptide sequence but have similar structure through evolution are termed convergent. This describes convergent evolution where unrelated proteins independently evolve similar structural features to perform similar functions. Divergent evolution refers to homologous proteins that have evolved from a common ancestor and share sequence similarity.

Multiple choice

Proteins which are different in peptide sequence but have a similar structure in the process of evolution are said to be:

  1. Convergent

  2. Divergent

  3. Opportunistic

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

Proteins that have different amino acid sequences (primary structure) but similar three-dimensional structures and often similar functions due to evolutionary pressures are said to show convergent evolution at the structural level. This is different from divergent evolution where homologous proteins evolve from a common ancestor.

Multiple choice

_____ are globular proteins.

  1. Beta globulin and fibrin

  2. Collagen and titin

  3. Elastin and beta globulin

  4. Beta globulin and titin

  5. Collagen and elastin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Beta globulin and fibrin are globular proteins.

Multiple choice

A set of globular proteins is

  1. Albumin, haemoglobin, thrombin

  2. Haemoglobin, myoglobin, elastin

  3. Keratin, elastin, myoglobin

  4. Thrombin, keratin, haemoglobin

  5. Keratin, haemoglobin, elastin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All are globular proteins.