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 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

The bonds responsible for the tertiary structure of proteins are:

  1. hydrogen bonds

  2. Vander wall forces

  3. disulphide bonds

  4. All the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The tertiary structure of proteins is stabilized by various interactions between the side chains of amino acids. These include hydrogen bonds, Van der Waals forces, ionic bonds, and covalent disulphide linkages. Since multiple types of interactions are responsible, all the listed options play a role.

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.

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

 Peptide linkages ($\displaystyle CONH$) are present in the primary structures of proteins while the secondary structures of proteins involve ______. 

  1. Coordinate bonding

  2. Ionic bonding

  3. hydrogen bonding

  4. none
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

While primary structure is held together by covalent peptide bonds, secondary structures (like alpha-helices and beta-pleated sheets) are formed and stabilized by hydrogen bonding between the backbone atoms.

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

The building block of proteins are:

  1. $\alpha$-hydroxy acid
  2. $\alpha$-amino acid
  3. $\beta$- hydroxy acid
  4. $\beta$- amino acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The building block of proteins are $ \displaystyle \alpha-$amino acids.
On hydrolysis, proteins gives  $ \displaystyle \alpha-$amino acids.
 $ \displaystyle \alpha-$amino acids have structure  $ \displaystyle H _2N- \underset {  \displaystyle   { \underset {  \displaystyle  \text { R } }{ | } } }{CH }-COOH$
Proteins $ \displaystyle \xrightarrow {H _2O}n H _2N- \underset {  \displaystyle   { \underset {  \displaystyle  \text { R } }{ | } } }{CH }-COOH$
Proteins are polypeptides and contain peptide linkage ($ \displaystyle - \underset {  \displaystyle   { \underset {  \displaystyle  \text { O } }{ || } } }{C }-NH-$ linkage)

Multiple choice

Which of the following is NOT a type of protein found in the human body?

  1. Enzymes

  2. Antibodies

  3. Hormones

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

Carbohydrates are not a type of protein. Proteins are made up of amino acids, while carbohydrates are made up of sugars.