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

Why does denaturation of an enzyme make it non-functional?

  1. Rearrangement of the amino acid sequence takes place.

  2. The 3D shape of the enzyme is disrupted.

  3. Peptide bonds break and amino acids are formed.

  4. New peptide bonds are formed.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The enzyme loses its function on denaturation because the 3D shape of the enzyme is disrupted. Due to disruption of shape, the active site is no more available.

Multiple choice

The arthropod exoskeleton is composed of a

  1. mixture of several kinds of polysaccharides

  2. mixture of several kinds of proteins

  3. single-complex polysaccharide called chitin

  4. single-complex protein called arthropodin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The arthropod exoskeleton is composed of a single-complex polysaccharide called chitin.

Multiple choice

The breakdown of proteins results in _________.

  1. sugars

  2. glycerol

  3. fatty acids

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

Amino acids are the chemical units or building blocks of the body that make up proteins. Protein substances make up the muscles, tendons, organs, glands, nails, and hair. The final digestion products of proteins are amino acids.

Multiple choice

Which among the following mutations has no effect on the functioning of the protein?

  1. Silent mutations

  2. Nonsense mutations

  3. Missense mutations

  4. Non-conservative mutations

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

Silent mutations codes for the same amino acid. A silent mutation has no effect on the functioning of the protein. A single nucleotide can change, but the new codon specifies the same amino acid, resulting in an unmutated protein.

Multiple choice

The enzymes catalysing the reaction involveing a metal is known as

  1. serine proteases

  2. cysteine proteases

  3. metalloproteinases

  4. aspartic proteases

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

Metalloproteinases constitute a family of enzymes from the group of proteases, classified by the nature of the most prominent functional group in their active site. These are proteolytic enzymes whose catalytic mechanism involves a metal. Most metalloproteases are zinc-dependent, some use cobalt.

Multiple choice

Protein synthesis in its intial stages is inhibited by

  1. Aurin

  2. Aurintricarboxylic acid

  3. Brilliant Blue

  4. Brilliant Green

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

Aurintricarboxylic acid (ATA) is a form of dye that is used to inhibit protein biosynthesis in its initial stages. Nominally, it is used in biological experiments as a protein inhibitor, and as an ammonium salt (known as aluminon) it is used as a reagent to estimate  aluminium in water, biological tissue and foods.

Multiple choice

Each antibody is a four polypeptide chain with

  1. three light chains and one heavy chain

  2. one light chain and three heavy chains

  3. two light chains and two heavy chains

  4. four light chains and no heavy chain
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Each antibody is a four polypeptide chain with two light chains and two heavy chains.

Multiple choice

Which among the following is a nonessential amino acid?

  1. Isoleucine

  2. Leucine

  3. Lysine

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

Asparagine is one of the 20 most common natural amino acids on Earth. It has carboxamide as the side-chain's functional group. It is a nonessential amino acid. Its codons are AAU and AAC.

Multiple choice

Which of the following amino acids plays its role in the urea cycle?

  1. Methionine

  2. Taurine

  3. Ornithine

  4. Histidine

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

Ornithine is an amino acid that plays a role in the urea cycle. L-Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. Therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess nitrogen.