Biomolecules TS

Hint

(a)

Hint

(d)

• 1. Formation of a peptide bond – ✅ This is enzyme-catalyzed in living cells by ribosomes, which act as ribozymes (RNA enzymes).

• 2. Carbonic anhydrase enzyme envolved 

• 3. Crossing over in meiosis – ✅ This process is mediated by proteins and enzymes like recombinases

Hint

(c)

“The association of coenzyme with apoenzyme is transient or reversible, not enduring.”

Hint

(a)

Hint

(b)

Hint

(d)

Hint

(d)

The first amino acid in the polypeptide chain
is called as N-terminal amino acid and the
last amino acid is called as C-terminal
amino acid

Hint

(d)

Incorrect: Most antibacterial drugs are non-competitive inhibitors or function by irreversibly inhibiting enzymes essential for bacterial survival (e.g., penicillin inhibiting transpeptidase). Competitive inhibitors are less commonly used in clinical settings due to issues like needing high concentrations to outcompete the natural substrate.

Hint

(c)

• (A) Incorrect: Lipids, even with molecular weight <800 Da, are largely insoluble in acid due to their hydrophobic nature. They typically do not fall into the acid-soluble fraction.

• (B) Incorrect: The acid-soluble fraction primarily contains small molecules (metabolites), not macromolecules like proteins, nucleic acids, polysaccharides, or lipids.

• (C) Correct: Macromolecules such as proteins, DNA, RNA, and polysaccharides from cytoplasm and organelles are not soluble in acid and therefore become part of the acid-insoluble fraction.

• (D) Incorrect: The acid-insoluble pool doesn’t exactly represent the cytoplasmic composition, as it excludes acid-soluble small molecules and includes macromolecules from organelles too.

Hint

(a)

Hint

(c)

❌ Evaluation of Reason (R)

This statement is false. In competitive inhibition, the inhibitor competes with the substrate for the active site of the enzyme. This competition reduces the formation of the ES complex because the inhibitor occupies the active site, preventing substrate binding. Therefore, the presence of a competitive inhibitor decreases the formation of the ES complex, not increases it

Hint

(a)

Ligases are a class of enzymes that facilitate the joining (ligation) of two molecules by forming new covalent bonds, often accompanied by the hydrolysis of ATP. Specifically, they catalyze the formation of bonds such as:

• C–O (carbon–oxygen)

• C–S (carbon–sulfur)

• C–N (carbon–nitrogen)

• P–O (phosphorus–oxygen)

Hint

(c)

Total Three Statements are correct

Statement IV: The building blocks or monomers of nucleic acid molecules are called nucleosides.

❌ Incorrect. The monomers of nucleic acids are nucleotides, not nucleosides. A nucleotide consists of a nitrogenous base, a five-carbon sugar, and one or more phosphate groups. In contrast, a nucleoside comprises only the nitrogenous base and the sugar, lacking the phosphate group.

Hint

(b)

❌ Why Reason (R) is not a correct explanation of Assertion (A):

While both statements are individually true, Reason (R) does not directly explain why nucleic acids consist solely of nucleotides. The composition of nucleic acids as chains of nucleotides is due to the polymerization of these monomer units, involving the sugar and phosphate groups forming the backbone, with nitrogenous bases as side groups. The fact that nitrogenous bases are heterocyclic compounds is a structural detail of the bases themselves and does not explain the overall composition of nucleic acids.

Hint

(c)

❌ Evaluating Reason (R):

While it’s accurate that enzymes, being proteins, possess a primary structure (their amino acid sequence), it’s incorrect to state that they have only a primary structure. Proteins, including enzymes, typically exhibit multiple levels of structure:

• Secondary structure: Local folding patterns like α-helices and β-sheets.

• Tertiary structure: The overall 3D shape of a single polypeptide chain.

• Quaternary structure: The assembly of multiple polypeptide subunits.

These higher-order structures are crucial for the protein’s functionality

Hint

(a)

Hint

(a)

Hint

(a)

The three chemically distinct components of a nucleotide are:

1. Nitrogenous base (a heterocyclic compound)

2. Pentose sugar (a monosaccharide)

3. Phosphate group (derived from phosphoric acid)

Hint

(c)

Malonate is a competitive inhibitor of the enzyme succinate dehydrogenase. It closely resembles the substrate succinate in structure and competes for binding at the enzyme’s active site. In competitive inhibition, increasing the concentration of the substrate (succinate) can overcome the inhibitor’s effect by outcompeting it for the active site, thereby increasing the reaction velocity. Doubtnut+1ScienceDirect+1Chemguide

Analysis of Other Options:

1. Increasing the temperature beyond 40°C: Enzymes have an optimal temperature range. Exceeding this range can lead to enzyme denaturation, reducing activity.

2. Decreasing the pH: Enzymes also have an optimal pH range. Altering the pH can affect enzyme structure and function, potentially decreasing activity. Decreasing the production of ATP by chemiosmosis: This process is downstream of the succinate dehydrogenase reaction in cellular respiration. Altering ATP production doesn’t directly influence the enzyme’s activity in the presence of malonate.