Class 12 Chemistry - CBSE
Biomolecules
The Biomolecules chapter in Class 12 CBSE Chemistry explores the chemical basis of life, focusing on the structures, properties, and biological functions of vital organic compounds. Students learn about carbohydrates, proteins, nucleic acids, vitamins, and lipids. You will study monosaccharides like glucose and fructose, the peptide linkages in proteins, the difference between DNA and RNA, and the classification of vitamins. This chapter is fundamental for understanding biochemistry and consistently features in board exams, testing both factual recall and structural identification. Mastering this chapter ensures easy-scoring marks in organic chemistry.
Start Learning FreeKey Concepts
Carbohydrates
Optically active polyhydroxy aldehydes or ketones, classified as monosaccharides, oligosaccharides, and polysaccharides based on hydrolysis behavior.
Proteins and Amino Acids
Polymers of alpha-amino acids linked by peptide bonds, exhibiting primary, secondary, tertiary, and quaternary structural levels essential for biological function.
Nucleic Acids
Biopolymers consisting of nucleotides (pentose sugar, nitrogenous base, and phosphate group) namely DNA and RNA, responsible for heredity and protein synthesis.
Enzymes
Biocatalysts, mostly globular proteins, that speed up specific biochemical reactions in living systems without being consumed.
Vitamins
Organic compounds required in small amounts for normal health, growth, and development, categorized into water-soluble (B, C) and fat-soluble (A, D, E, K).
Important Formulas
Board Exam Info
In the CBSE Class 12 Chemistry board exam, Biomolecules typically carries around 3 to 4 marks. Questions usually include direct conceptual definitions, differentiating between DNA and RNA, explaining peptide linkages, identifying reducing and non-reducing sugars, or structural features of glucose.
Frequently Asked Questions
What is the difference between a reducing and non-reducing sugar?
Reducing sugars contain free aldehydic or ketonic groups and can reduce Tollens' or Fehling's reagent (e.g., glucose, lactose). Non-reducing sugars do not have free functional groups because their carbonyl groups are involved in glycosidic bond formation (e.g., sucrose).
What is denaturation of proteins?
Denaturation is the process where native proteins lose their secondary and tertiary structures due to physical changes like temperature or chemical changes like pH, resulting in loss of biological activity, such as the boiling of an egg.
Why are vitamin C and vitamin B complex stored in our bodies?
Vitamin C and B-complex vitamins are water-soluble and easily excreted in urine, which is why they cannot be stored in our body and must be supplied regularly through diet, unlike fat-soluble vitamins.
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