Biology · 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

Which of the following is not correct about proteins?

  1. It is known to form tissues in the body.

  2. Nitrogen is its main constituent.

  3. It can be directly stored in the body.

  4. It can release energy when the body is in its need.

  5. It gets converted into urea and excretes out of the body with urine.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The protein is not stored in the body. Hence, this statement is incorrect.

Multiple choice

Which of the following amino acids acts as precursor to hormones epinephrine, norepinephrine and dopamine?

  1. L-2-Amino-3-(4-hydroxyphenyl)propanoic acid

  2. 2-Amino-3-hydroxybutanoic acid

  3. (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid

  4. Pyrrolidine-2-carboxylic acid

  5. 2-Amino-3-phenylpropanoic acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In dopaminergic cells in the brain, tyrosine (L-2-Amino-3-(4-hydroxyphenyl)propanoic acid) is converted to l-dopa by the enzyme tyrosine hydroxylase (TH). TH is the rate-limiting enzyme involved in the synthesis of the neurotransmitter dopamine. Dopamine can be converted into norepinephrine and epinephrine.

Multiple choice

Which of the following sets represents essential amino acids?

  1. Tryptophan, Histidine, Aspartic acid, Proline, Leucine

  2. Valine, Leucine, Tryptophan, Lysine, Histidine

  3. Alanine, Proline, Aspartic acid, Glycine, Cysteine

  4. Valine, Leucine, Aspartic acid, Glycine, Cysteine

  5. Alanine, Valine, Lysine, Glycine, Tryptophan
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Correct answer 

Multiple choice

Which of the following statements is/are not correct?

P. Coordination number of iron in rubredoxin is 6. Q. Oxidation state of iron in transferrin is 2. R. Haemosiderin is a cell Fe storage protein. S. The protein coat of ferritin is a hollow sphere of 24 polypeptide chains.

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. R and S
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct. This option is wrong because haemosiderin is a cell Fe storage protein and protein coat of ferritin is a hollow sphere of 24 polypeptide chains.

Multiple choice

Which of the following statements are incorrect?

  1. All transferrins are lipoproteins.
  2. The transport of iron from storage sites in cellular ferritin or hemosiderin occurs via serum-transport protein transferrin.
  3. Each transferrin binds with only one iron atom.
  4. The protein coat of ferritin is a hollow sphere of 24 polypeptide chains.

  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

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

This option is correct because all transferrins are glycoproteins and have a high molecular weight, they bind with two iron atoms.

Multiple choice

Which of the following is a pair of cell Fe storage proteins?

  1. Haemoglobin and myoglobin

  2. Transferrin and ferritin

  3. Ferritin and haemosiderin

  4. Haemosiderin and cytochrome c

  5. Cytochrome C and haemoglobin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because ferritin and haemosiderin are cell Fe storage proteins.