Class 11 Biology - Biomolecules

Exercises

1. What are macromolecules? Give examples.

Answer: Macromolecules (or biomacromolecules) are large, complex chemical compounds found in the acid-insoluble fraction of living tissues. They have molecular weights ranging from 10,000 daltons and above. With the exception of lipids, all macromolecules are polymeric substances.

Examples:

Proteins: Polymers of amino acids.
Polysaccharides: Polymers of monosaccharides (e.g., starch, cellulose).
Nucleic Acids: Polymers of nucleotides (DNA and RNA).

2. What is meant by tertiary structure of proteins?

Answer: The tertiary structure of a protein refers to the three-dimensional view of the protein formed when the long protein chain (polypeptide) is folded upon itself like a hollow woolen ball. It involves interactions between the R-groups of the amino acids. Significance: This 3D conformation is absolutely necessary for the many biological activities of proteins, such as forming the active sites of enzymes.

5. Explain the composition of triglyceride.

Answer: A triglyceride is a simple lipid formed from one molecule of glycerol (trihydroxy propane) and three molecules of fatty acids. Each of the three hydroxyl (-OH) groups of the glycerol molecule is esterified with the carboxyl (-COOH) group of a fatty acid. These fatty acids can be saturated or unsaturated.

7. Draw the structure of the amino acid, alanine.

Answer: Alanine is an $\alpha$ -amino acid where the R-group is a methyl group ( $-CH_3$ ). The structure is:

      NH2
       |
  H —  C — COOH
       |
      CH3

11. Describe the important properties of enzymes.

Answer:

Chemical Nature: Almost all enzymes are proteins (exceptions include ribozymes which are RNA).
Efficiency: They are highly efficient biocatalysts, increasing reaction rates by millions of times (e.g., carbonic anhydrase).
Specificity: Each enzyme is highly specific for a particular substrate and reaction.
Active Site: They possess a specific pocket or crevice called the 'active site' where the substrate binds.
Lowering Activation Energy: They function by lowering the activation energy barrier required for a chemical reaction to proceed.
Sensitivity to Temperature and pH: They function optimally in narrow ranges of temperature and pH; extreme heat denatures them.
Saturation: At high substrate concentrations, the reaction reaches a maximum velocity (V_max) because all enzyme active sites are occupied.
Reversibility: Most enzymatic reactions are reversible.
Co-factors: Some enzymes require non-protein co-factors (prosthetic groups, co-enzymes, or metal ions) to become catalytically active.

Exercises

Examples:

Proteins: Polymers of amino acids.

Polysaccharides: Polymers of monosaccharides (e.g., starch, cellulose).

Nucleic Acids: Polymers of nucleotides (DNA and RNA).

Answer: Alanine is an

\alpha

-amino acid where the R-group is a methyl group (

-CH_3

). The structure is:

      NH2
       |
  H —  C — COOH
       |
      CH3

Answer:

Chemical Nature: Almost all enzymes are proteins (exceptions include ribozymes which are RNA).

Efficiency: They are highly efficient biocatalysts, increasing reaction rates by millions of times (e.g., carbonic anhydrase).

Specificity: Each enzyme is highly specific for a particular substrate and reaction.

Active Site: They possess a specific pocket or crevice called the 'active site' where the substrate binds.

Lowering Activation Energy: They function by lowering the activation energy barrier required for a chemical reaction to proceed.

Sensitivity to Temperature and pH: They function optimally in narrow ranges of temperature and pH; extreme heat denatures them.

Saturation: At high substrate concentrations, the reaction reaches a maximum velocity (V_max) because all enzyme active sites are occupied.

Reversibility: Most enzymatic reactions are reversible.

Co-factors: Some enzymes require non-protein co-factors (prosthetic groups, co-enzymes, or metal ions) to become catalytically active.

Class 11 Biology - Biomolecules

Class 11 Biology - Biomolecules

Exercises

1. What are macromolecules? Give examples.

2. What is meant by tertiary structure of proteins?

5. Explain the composition of triglyceride.

7. Draw the structure of the amino acid, alanine.

11. Describe the important properties of enzymes.

On this page

Class 11 Biology - Biomolecules

Class 11 Biology - Biomolecules

Exercises

1. What are macromolecules? Give examples.

2. What is meant by tertiary structure of proteins?

5. Explain the composition of triglyceride.

7. Draw the structure of the amino acid, alanine.

11. Describe the important properties of enzymes.

On this page