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

In growing children, the conditionally amino acids are termed as essential amino acids. Which of the following describes the same? P. Cysteine
Q. Arginine
R. Serine

  1. P only

  2. Q only

  3. R only

  4. P and Q

  5. Q and R
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In our diet, those amino acids which are not synthesized in our body and take in the form of diet (food) are termed as as essentially amino acids. Cysteine and Arginine are come in the class conditionally amino acids. However, cysteine, a sulphur-containing amino acid, tyrosine and arginine are required by infants and growing children. In the cases, these amino acids are termed as essential amino acids and required in the diet besides of conditionally amino acids.Hence, both P and Q are termed as essentially amino acid in case of growing children.

Multiple choice

Which of the following are indispensable amino acids for humans? P. Proline
Q. Tyrosine
R. Leucine
S. Lysine

  1. P, Q

  2. Q, R

  3. R, S

  4. Q, R, S

  5. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The indispensable amino acids or essential amino acids are those amino acids that cannot be synthesized by the organism being considered, and therefore must be supplied in its diet. The amino acids regarded as essential for humans are phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, and histidine. The amino acids arginine, cysteine, glycine, glutamine, proline, serine and tyrosine are considered as conditionally essential amino acids, meaning they are not normally required in the diet, but must be supplied exogenously to specific populations that do not synthesize them in adequate amounts.Hence, R and S both are indispensable amino acids and others are conditionally amino acids.

Multiple choice

Napins are seed storage proteins, which consist of two polypeptide chains. Which of the following plant species contain(s) napin protein? P. Brassica campestris Q. Zea mays R. Degenia velebitica

  1. P only

  2. Q only

  3. R only

  4. Q, R

  5. P, R
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Osborne (1924) classified seed storage proteins into groups on the basis of their extraction and solubility in water (albumins), dilute saline (globulins), alcohol-water mixtures (prolamins), and dilute acid or alkali (glutelins). In Crucifereae or Bressicaceae family, the seed storage proteins are called napins. The examples of cruciferae family are- Brassica campestris, Degenia velebitica, Arabis aculeolata etc. Zea mays belongs to the family Poaceae and contains zein as seed storage proteins.

Multiple choice

Proteins involved in Hsp70 system are ___________.

Chaperons are heat shock proteins, which facilitate the interactions on the polypeptide surface to finally give the specifc conformation of proteins. They are categorised into two major groups; Hsp70 system and chaperonine system.

  1. Hsp 70 and Hsp 30

  2. Hsp 40 and Hsp 100

  3. Hsp 70 and Hsp 20

  4. Hsp 70 and Hsp 40

  5. Hsp 50 and Hsp 30
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hsp 70 and Hsp 40: 70 KD is a heat shock protein and 40 KD is a heat shock protein that can bind individually to the substrate, and help in the correct formation of protein folding.

Multiple choice

Which of the following statements is not true for chaperonin?

Chaperons are heat shock proteins, which facilitate the interactions on the polypeptide surface to finally give the specifc conformation of proteins. They are categorised into two major groups; Hsp70 system and chaperonine system.

  1. This system contains 60 KDa Hsp.

  2. This system contains 10 KDa Hsp.

  3. It works in association with Hsp 70 system.

  4. It is an oligomeric assembly into which the folded proteins are inserted.

  5. It binds individually to the substrate and helps in the correct formation of protein folding.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

It is true for Hsp 70 system but not for chaperonin. Chaperonin is an oligomeric assembly, which forms a structure into which the folded protein is inserted. This system mainly has Hsp 60 and Hsp10 and is required at later part of the protein folding process and often work in association with Hsp 70 system.

Multiple choice

A research student viewing a PDB structure in PyMol concludes that the protein is surely involved in dimer formation but further inferred that it does not involve in any direct interaction with DNA. Which of the following clues helps you infer the same?

  1. Zinc finger

  2. Helix-turn-helix

  3. Homeodomain

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

Leucine zippers are exclusively involved in protein-protein dimerization, while they ineract with DNA’s sugar and phosphate molecules in an induced way, rather than direct binding.

Multiple choice

What does an α-helix signify?

  1. Aggregation of protein.

  2. Tertiary structure of protein.

  3. Secondary structure of protein.

  4. Primary structure of protein.

  5. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The secondary structure of protein is formed by the folding of linear polypeptide chain into regular structure. The folding of polypeptide chain occurs because NH and CO group in the peptide chain are linked with hydrogen bonds. The α-helix is a rod-like structure. There is an imaginary axis at the middle of the helix. Around the imaginary axis, the polypeptide chain is wound tightly.

Multiple choice

Which of the following is a simple protein?

  1. Keratin

  2. Chymotripsinogen

  3. Glycoproteins

  4. Lipoproteins

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

Depending on the composition, simple proteins are those proteins, which consist of amino acid residues only. They do not contain any other chemical components. Chymotripsinogen is one such simple protein.

Multiple choice

Depending on polarity and charge of R groups match the following amino acids: Name Type

  1. Glycine A. Polar Uncharged amino acid
  2. Glutamine B. Non-polar aliphatic amino acid
  3. Tyrosine C. Negatively charged amino acid
  4. Glutamate D. Positively charged amino acid
  5. Histidine E. Aromatic amino acid

  1. 1 - B, 2 - D, 3 - E, 4 - C, 5 - A

  2. 1 - B, 2 - A, 3 - E, 4 - C, 5 - D

  3. 1 - C, 2 - A, 3 - E, 4 - B, 5 - D

  4. 1 - B, 2 - D, 3 - E, 4 - A, 5 - C

  5. 1 - B, 2 - E, 3 - D, 4 - C, 5 - A
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Non-polar aliphatic amino acids have hydrophobic and non-polar R groups. Glycine is a non-polar aliphatic amino acid. Polar uncharged amino acids have hydrophilic R groups. Glutamine is a polar uncharged amino acid. Aromatic amino acids are non-polar and contain aromatic side chains. Tyrosine is an aromatic amino acid. Negatively charged amino acids possess R groups with net negative charge. Glutamate is a negatively charged amino acid. Positively charged amino acids have R groups, which are hydrophilic and with positive charge. Histidine is a positively charged amino acid.

Multiple choice

One molecule of secretory IgA can at most bind to _____.

  1. 10 molecules of Ag

  2. 4 molecules of Ag

  3. 2 molecules of Ag

  4. 1 molecules of Ag

  5. 5 molecules of Ag
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

IgA is a dimer where 2 four-chain units are held together by the J chain through disulfide bridges. Each four chain unit has 2(paratopes) antigen binding sites. Thus 2 four chain unit is capable of binding 4 Ag molecules.

Multiple choice

What is the type of interaction between this particular Ag with 4 epitopes and the IgG Ab?

In an antigen antibody interaction, in the zone of equivalence, the isolated antigen IgG complex was found to be in the molar ratio of Antigen : IgG = 2 : 1

  1. Affinity

  2. Cross reactivity

  3. Avidity

  4. Alloreactivity

  5. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Avidity when the Ag consists of many epitopes (here 4) are mixed with Ab (here IgG) having multiple (here 2) binding sites, the interaction of such type between multivalent Ab and Ag is called, the Avidity.