Biology ยท 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 cytoskeletal protein of microtubules is

  1. tubulin

  2. tubulin and actin

  3. actin and ankyrin

  4. myosin

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

Tubulin heterodimer is the structural subunit of microtubules, which are cytoskeletal elements that are essential for intracellular transport and cell division.

Multiple choice

Which of the following statements are FALSE?

  1. Synteny refers to local conservation of gene order.
  2. The helix content of a protein can be determined using circular dichromism spectroscopy.
  3. In zinc finger proteins, the amino acid residues that coordinate zinc are Cys and Met.
  4. The production of secondary metabolites in plant cell cultures is enhanced by the addition of elicitors.

  1. Only 1 and 2

  2. Only 1 and 3

  3. Only 2 and 3

  4. Only 2 and 4

  5. Only 3 and 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, this is the correct answer, as both the statements are false. Synteny refers to gene duplication from a common ancestor. This is the condition in which two or more gene loci are present on the same chromosome. During evolution, rearrangements may cause the loss of synteny, or else it will be retained. Translocations can cause gain of synteny. In zinc finger proteins, the amino acid residues that coordinate zinc are Cys and His. Zinc fingers coordinate zinc ions with a combination of cysteine and histidine residues. They can be classified by the type and order of these zinc coordinating residues (e.g., Cys2His2, Cys4, and Cys6).

Multiple choice

Which of the following is/are essential amino acid(s)?

  1. Alanine and glycine

  2. Cysteine

  3. Leucine and isoleucine

  4. Proline and serine

  5. Asparagine and glutamine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

These are essential amino acids. These are simple amino acids. These are non-essential acidamide amino acids.

Multiple choice

When is a peptide bond formed?

  1. During synthesis of proteins

  2. During synthesis of disaccharides

  3. During synthesis of long chain fatty acids

  4. During synthesis of polynucleotides

  5. During synthesis of vitamins
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The bond formed between two amino acids is called peptide bond. A protein molecule is made of many amino acids linked together by peptide bond.

Multiple choice

The level of protein structure represented by the alpha-helix shape is

  1. quaternary

  2. tertiary

  3. secondary

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

The alpha-helix is a type of secondary protein structure. Secondary structure refers to local folding patterns stabilized by hydrogen bonds between the backbone amide and carbonyl groups. The alpha-helix and beta-sheet are the two main types of secondary structure. Primary structure is the amino acid sequence, tertiary is overall 3D folding, and quaternary involves multiple polypeptide chains.

Multiple choice

The process that joins amino acids together to make enzymes is

  1. oxidation

  2. denaturation

  3. dehydration synthesis

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

Dehydration synthesis (also called condensation) joins amino acids by removing a water molecule between them, forming peptide bonds that create polypeptide chains and enzymes. Oxidation involves electron loss, denaturation unfolds proteins, and hydrolysis breaks them down.

Multiple choice

Which of the following pairs of enzymes is used to isolate genetic material?

  1. Chitinase and lipase

  2. Lysozyme and cellulase

  3. Lysozyme and lipase

  4. Lipase and cellulase

  5. Lipase and chitinase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Genetic material of organism is deoxyribonucleic acid or DNA. In order to cut the DNA with restriction enzymes, it needs to be in pure form, free from other macromolecules. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. This can be achieved by treating the bacterial cells/plant or animal tissues with enzymes such as lysozyme, cellulase and chitinase. Hence, lysozyme and cellulase enzymes are used in the isolation of the genetic material.