Comprehensive notes on Water, Carbohydrates, Proteins, Lipids, Nucleic Acids (DNA/RNA) and enzymes for Chapter 4 Biological Molecules, 11th Class Biology.
Biochemistry: The branch of biology dealing with the chemical components and chemical processes in living organisms.
Chemical Composition of Cell: All living organisms form protoplasm produced from bio-elements. Six main elements (C, H, O, N, P, Ca) make up 99% of the total mass.
Carbon Importance: Carbon is tetravalent, forming stable covalent bonds with other C atoms (catenation) and H, O, N, S, P. It forms the backbone of organic molecules.
Definition: Polyhydroxy aldehydes or ketones, or substances that yield these on hydrolysis. Formula: Cn(H2O)n.
Classification:
Definition: Heterogeneous group of organic compounds insoluble in water but soluble in organic solvents (ether, alcohol). High energy store (double that of carbs).
Classification:
Composition: Polymers of Amino Acids linked by Peptide Bonds (C-N linkage). Most abundant organic compounds in cells (50% dry weight).
Structure Levels:
Definition: Polymers of Nucleotides. Discovered by F. Miescher (1869). Two types: DNA and RNA.
Nucleotide Structure: Made of Pentose Sugar (Ribose/Deoxyribose) + Nitrogenous Base (Purines A/G, Pyrimidines C/T/U) + Phosphate Group. Linked by Phosphodiester bonds.
Proposed in 1953:
RNA is single-stranded and contains Uracil (U) instead of Thymine.