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

Match entries in Group I (amino acids) with that in Group II (their metabolic precursors) and select the correct answer.

Group I
Group II
P. Tyrosine 1. Threonine
Q. Serine 2. Phenylalanine
R. Isoleucine 3. Glutamate
S. Proline 4. Glycerate 3-phosphate

  1. P - 1, Q - 2, R - 3, S - 4

  2. P - 2, Q - 4, R - 1, S - 3

  3. P - 2, Q - 3, R - 1, S - 4

  4. P - 3, Q - 2, R - 1, S - 4

  5. P - 4, Q - 2, R - 3, S - 1
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phenylalanine acts as metabolic precursor to tyrosine. Glycerate 3-phosphate acts as a precursor for serine which in turn, can act as precursor to create cysteine and glycine through the homocysteine cycle. Threonine acts as metabolic precursor to isoleucine. Glutamate acts as metabolic precursor to glutamic acid, proline and arginine.

Multiple choice

Which of the following statements are false?

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

Select the correct answer using codes given below:

  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

Coordination number of iron in rubredoxin is 4. Oxidation state of iron in transferrin is 3.

Multiple choice

The main structural feature of proteins is

  1. ester linkage

  2. ether linkage

  3. peptide linkage

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

Proteins are the polymers of amino acids which are connected to each other by peptide bond or peptide linkage. 

Multiple choice

The protein molecule, permanently attached to the biological membrane, is

  1. transmembrane protein

  2. peripheral membrane proteins

  3. integral membrane protein

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

An integral membrane protein (IMP) is a protein molecule that is permanently attached to the biological membrane. Proteins that cross the membrane are surrounded by annular lipids, which are defined as lipids that are in direct contact with a membrane protein.

Multiple choice

The antigen-binding site of an antibody is referred as

  1. conformational epitope

  2. linear epitope

  3. paratope

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

The paratope is the part of an antibody which recognises an antigen, the antigen-binding site of an antibody. It is a small region (of 15-22 amino acids) of the antibody's Fv region and contains parts of the antibody's heavy and light chains.

Multiple choice

Proteins make up about half of the human body's dry weight. Among the following, ------------------------ is a protein.

  1. Collagen

  2. Collodion

  3. Congo red

  4. Coomassie Brilliant Blue
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Collagen is a group of naturally occurring proteins found, in nature, exclusively in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content.

Multiple choice

The polynucleotide chain is cloverleaf-shaped in ________.

  1. Ribosomal RNA (rRNA)

  2. Transfer RNA (tRNA)

  3. Messenger RNA (mRNA)

  4. DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It represents about 10 to 15% of the total RNA in the cell. It has the shortest molecule having only about 80 to 100 nucleotides. The polynucleotide chain is folded on itself to have the shape of a cloverleaf. The molecule has three lateral loops, a DHU loop, a t loop and an anticodon loop. The anticodon loop bears a triplet combination of nitrogen bases, called anticodon. It is complementary to a codon of mRNA.

Multiple choice

Which of the following statements is correct regarding histone proteins?

  1. They are acidic proteins and are present in prokaryotes.

  2. They are basic proteins and are present in prokaryotes.

  3. They are acidic proteins and are present in eukaryotes.

  4. They are basic proteins and are present in eukaryotes.

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Histones are basic proteins and are present in eukaryotes.

Multiple choice

Protein of silk thread is

  1. fibroin

  2. albumin

  3. keratin

  4. globulin

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

The protein fibre of silk is mainly composed of fibroin and is produced by certain insect larvae to form cocoons.

Multiple choice

The protein present in silk thread is

  1. fibroin

  2. keratin

  3. albumin

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

Fibroin is an insoluble protein present in silk created by spiders, the larvae of Bombyx mori etc.

Multiple choice

Which of the following are histones?

  1. Acidic proteins

  2. Basic proteins

  3. Mucoproteins

  4. Glycoproteins

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

Histones are highly alkaline or basic proteins that are found in eukaryotic cell nuclei.