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 bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

Enzymes are

  1. Carbohydrates

  2. Nucleic acids

  3. Globular proteins

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

Option (C) is correct.
Enzymes are globular proteins, and catalyze metabolic reactions in living organisms.
They have a specific tertiary structure with an active site complementary to the substrate. They can speed up a reaction but do not get used up. Their activity can be affected by temperature and $pH$.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

The type of bond that is most important in maintaining secondary structure of a protein is 

  1. disulphide bridges

  2. hydrogen bonding within the backbones
  3. hydrogen bonding between $R$ group

  4. salt bridges
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Secondary structure of a protein is generally maintained y hydrogen bonding between the $-NH$ group of one amide and the $C=O$ group of another amide
Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

The sequence in which the $\alpha$-amino acids are linked to one another in a protein molecule is called its:

  1. primary structure

  2. secondary structure

  3. tertiary structure

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

The primary structure of a protein is defined by the linear sequence of amino acids linked by peptide bonds. Secondary, tertiary, and quaternary structures refer to the folding and spatial arrangement of this chain.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

Which of the following statements are true about (X) and (Y)?
X)  Globular Protein               Y)  Fibrous Protein
a.These are linear condensation polymers.
b. Insoluble in water.
c. These proteins have three dimensional folded structure.
d. These are cross linked protein.
e. Soluble in water
f. These are held together by intermolecular hydrogen bond.

  1. X = a, b, c; Y = d, e, f

  2. X = c, d, e; Y = a, b, f

  3. X = b, c, a; Y = c, b, f

  4. X = a, e, f; Y = b, c, f
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Globular Proteins have three dimensional folded structure.
These are cross linked protein.
They are Soluble in water.
Fibrous Proteins are linear condensation polymers.
They are Insoluble in water.
These are held together by intermolecular hydrogen bond.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

Which structural feature distinguishes proline from other natural $\alpha$-amino acids :

  1. It is optically inactive

  2. It contains aromatic group

  3. It is dicarboxylic acid

  4. It has a secondary amine

  5. It contains two amino groups
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Proline is the only proteinogenic amino acid whose side-group links to the -amino group and, thus, is also the only proteinogenic amino acid containing a secondary amine at this position.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

The sequence in which amino acids are linked to one another in a protein molecule is called its:

  1. Primary structure

  2. Secondary structure

  3. Tertiary structure

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

Proteins may have one or more polypeptide chains. Each polypeptide in a protein has amino acids linked with each other in a specific sequence and it is this sequence of amino acids that is said to be the primary structure of that protein.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

The primary structure of proteins is associated with this:

  1. amino acid sequence
  2. $\beta$ -pleated sheet structure

  3. conformation

  4. relative position of subunits
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Primary structure refers specifically to the unique sequence of amino acids in a polypeptide chain. Other options describe higher-level folding or structural organization.

Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

Myoglobin can be analysed for its quaternary structure.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Myoglobin is a simple protein consisting of a single polypeptide. Since the quaternary structure is composed of an assembly of subunits of polypeptides, myoglobin does not have a quaternary structure. Due to the lack of multiple subunits, it has the highest level of structure as tertiary. Hemoglobin, on the other hand,  is composed of multiple polypeptide subunits, each capable of binding and transporting one molecule of oxygen in the blood, thus giving it a quaternary structure.