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

Amino acid lacking an optically active α-carbon is

  1. Arginine

  2. Histidine

  3. Glutamic acid

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

Glycine has a hydrogen atom as its side chain. Since it has two identical substituents (two hydrogens) on the alpha-carbon, it is achiral and not optically active.

Multiple choice

Globular proteins are said to be in β-conformation, if

  1. they contain β strands only

  2. they contain α-helices interspersed with β-strands

  3. they are twisted in a left-handed helix instead of the usual right-handed one

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Globular proteins often contain complex secondary structures, including both alpha-helices and beta-strands. Beta-conformation refers to the presence of beta-sheets or strands within the protein structure.

Multiple choice

Denatured protein has a/an

  1. Folded polypeptide chain

  2. Unfolded polypeptide chain

  3. Polypeptide chain liked with disulphide bonds

  4. Polypeptide chain linked with weak covalent bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Denaturation is the process where a protein loses its native three-dimensional folded structure. This results in an unfolded polypeptide chain, rendering the protein biologically inactive.

Multiple choice

Interferons are anti _________ proteins.

  1. viral

  2. bacterial

  3. protozoan

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

Interferons are signaling proteins released by host cells in response to the presence of several viruses, acting as antiviral agents.

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.