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

During the artificial peptide synthesis, the amino acids are coupled by

  1. N,N-Dicyclohexylcarbodiimide

  2. Iron(III) chloride

  3. Orthoformic acid

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

N,N-Dicyclohexylcarbodiimide is an organic whose primary use is to couple amino acids during artificial peptide synthesis. Under standard conditions, it exists in the form of white crystals with a heavy, sweet odour.

Multiple choice

Which of the following compounds suppresses racemization & enhances the efficiency of peptide synthesis?

  1. Benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate

  2. Hydroxybenzotriazole

  3. 1-Hydroxy-7-azabenzotriazole

  4. N,N-Diisopropylcarbodiimide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hydroxybenzotriazole is an organic compound that is a derivative of benzotriazole. It is mainly used to suppress racemization and improve the efficiency of peptide synthesis. It is a white crystalline powder. Commercial it always contains some water (~11.7% wt as the HOBT monohydrate crystal) because it is explosive.

Multiple choice

Bacterial protein toxins are the most powerful human poisons known and retain high activity at very high dilutions. After invading the human body, these toxins get neutralised by which of the following components of immune system?

  1. Complement

  2. Antibodies

  3. Toxoids

  4. PGE2

  5. Proteolytic enzymes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Antibodies may block the binding to target cell and would increase the rate of removal of toxin from the circulation by immune complex formation.

Multiple choice

Which among the following compouds is not a protein?

  1. Collagen

  2. Elastin

  3. Pikachurin

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

Pikachurin is a polysaccharide that in humans is encoded by the EGFLAM gene.Pikachurin is a dystroglycan-interacting polysaccharide which has an essential role in the precise interactions between the photoreceptor ribbon synapse and the bipolar dendrites.

Multiple choice

The process of dehydration is associated with the formation of --------------------- bond.

  1. quintuple

  2. sextuple

  3. glycosidic

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

A peptide bond (amide bond) is a covalent chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids.

Multiple choice

The entropically unfavourable folded conformation of proteins gets stable by the formation of -------------------------- bonds.

  1. salt

  2. cation-π interaction

  3. metallic

  4. hydrogen

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

Salt bond fall into the broader category of noncovalent interactions. A salt bond is actually a combination of two noncovalent interactions: hydrogen bonding and electrostatic interactions .This is most commonly observed to contribute stability to the entropically unfavourable folded conformation of proteins.

Multiple choice

Immunoglobulins are divided into five different classes on which of the following bases?

  1. Amino acid sequence in the constant region of light chain

  2. Amino acid sequence in the variable region of heavy chain

  3. Amino acid sequence in the constant region of heavy chain

  4. Amino acid sequence in the variable region of light chain
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Immunoglobulins can be divided into five different classes based on differences in the amino acid sequences in the constant region of the heavy chains. They are IgD, IgM, IgE, IgA and IgG.

Multiple choice

Which of the following statements is true?

  1. Denatured involves changes in the primary structure of proteins.

  2. Respiration involves conversion of bigger molecules into smaller molecules.

  3. The blood platelets act as defence against infections.

  4. Cancer is a congenital disease.

  5. At isoelectric point, an α-amino acid has the minimum solubility.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This statement is true because at isoelectric point, an α-amino acid has the minimum solubility.

Multiple choice

Which of the following statements is/are true? A. Antibodies are formed in the body only on demand. B. All DNA and RNA molecules contain adenine, guanine and cytocine. C. Casein, the milk protein has phosphate groups as prosthetic groups.

  1. Both A and B

  2. Both A and C

  3. B and C

  4. A, B, and C

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct,  because antibodies are formed in the body only on demand, adenine, guanine and cytocine are found in all DNA and RNA molecules and the milk protein casein has phosphate groups as prosthetic groups.

Multiple choice

Which of the following are examples of iron-sulphur proteins?

  1. Rubredoxin
  2. Methane monooxygenase
  3. Rieske proteins
  4. Aconitase

  1. 1 and 2

  2. 1, 2 and 3

  3. 1, 3 and 4

  4. 2 and 3

  5. 2, 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because Rubredoxin is a small iron-sulphur protein found in various sulphur-metabolizing bacteria, Rieske proteins are iron-sulphur protein components of cytochrome bc1 complexes and cytochrome b6f complexes which were first discovered and isolated by John S. Rieske and co-workers in 1964 and Aconitase is an iron-sulphur protein that catalyses the interconversion of citrate and isocitrate