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

The fluid absorbing substance of the cartilage is

  1. chitin

  2. chondroitin

  3. kinin

  4. keratin

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

Chondroitin is a molecule that occurs naturally in the body. It is a major component of cartilage. Chondroitin helps to keep cartilage healthy by absorbing fluid particularly water into the connective tissue. It may also block enzymes that break down cartilage, and it provides the building blocks for the body to produce new cartilage.

Multiple choice

Which of the following amino acids get replaced by valine amino acid in sickle cell anemia patients?

  1. Histidine

  2. Lysine

  3. Cysteine

  4. Glutamic acid

  5. Aspartic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A single nucleotide pair alteration is the cause of sickle cell anemia: the template strand of mutated sickle cell DNA has an A rather than a T. U takes the place of A in the mRNA. A valine amino acid is made in the sickle cell haemoglobin instead of a glutamic acid. GAG which codes for the amino acid glutamic acid is changed to GTG for valine as a result of the mutation in the position of second nucleotide of the codon GAG.

Multiple choice

Peptide bond is formed between

  1. two amino groups

  2. carboxyl group and ketone group

  3. amino group and carboxyl group

  4. two carboxyl groups
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A peptide bond forms through a condensation reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another amino acid, releasing a water molecule. This is the fundamental bond that links amino acids together in proteins.

Multiple choice

B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein and exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form of toxin. This is due to __________.

  1. the acidic pH of the gut, which solubilises the crystals

  2. the neutral pH of the gut, which solubilises the crystals

  3. the alkaline pH of the gut, which solubilises the crystals

  4. the alkaline pH of the respiratory tract, which solubilises the crystals

  5. the acidic pH of the respiratory tract, which solubilises the crystals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

B. thuringiensis forms protein crystals during a particular phase of its growth. These crystals contain a toxic insecticidal protein and exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form of toxin.

Multiple choice

Which of the following enzymes helps in the production of urea?

  1. Uricase

  2. Urease

  3. Arginase

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Arginase is the final enzyme in the urea cycle (ornithine cycle) that converts arginine to urea and ornithine in the liver. This is the fifth and final step of urea production. Urease breaks down urea (opposite direction), and uricase acts on uric acid, not urea production.

Multiple choice

Separation of amino acid into amino and carboxyl group is known as

  1. deamination

  2. excretion

  3. amination

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

Deamination is the process of removing an amino group (-NH2) from an amino acid. This is the first step in amino acid catabolism and is essential for producing energy from proteins or for converting amino acids into other compounds. The process occurs primarily in the liver and produces ammonia, which is then converted to urea for safe excretion.

Multiple choice

Primary structure of a protein is formed by

  1. hydrogen bonds

  2. disulphide bonds

  3. peptide bonds

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

The primary structure refers to amino acid linear sequence of the polypeptide chain. The primary structure is held together by covalent or peptide bonds.