BIOMOLECULES

POINTS TO REMEMBER :

• Biomolecules: All the carbon compounds that we get from living tissues.
• Macromolecules: Molecules which have molecular weights less than one thousand dalton.
• Amino acids: Organic compounds containing an amino group and one carboxyl group (acid group) and both these groups are attached to the same carbon atom called α carbon.
• Twenty types of amino acids occur in proteins.
• Based on number of amino and carboxyl groups, amino acids can be:
  • Acidic: e.g. Glutamic acid
  • Basic: e.g. Arginine and lysine
  • Neutral: e.g. valine, alanine.
  
  
• Aromatic amino acids are tyrosine, phenylalanine, and tryptophan.
• Amino acids are ionizable into zwitterionic form.

Lipids :

• Water insoluble, containing C, H, O.
• They could be simple fatty acids.
• A fatty acid has a carboxyl group attached to an R group.
• The R group may be a methyl group (-CH₃) or ethyl (-C₂H₅) or higher number of-CH₂ group (1 carbon to 19 carbon). E.g. palmitic acid with 19 carbons, arachidonic acid has 20 carbons.
• Fatty acids could be saturated (without double bond) or unsaturated (with one more (c=c) double bond.
• Another example of lipid is glycerol which is trihydroxy propane.
• Many lipids may have both glycerol and fatty acids.
• Fatty acids esterified with glycerol to form mono, di or triglycerides.
• These are also called fats and oils based on the melting points.
• Oils have low melting points (e.g. gingely oil).
• Phospholipids are compound lipids with phosphorus and a phosphorylated organic compound. They are found in the cell membrane. e.g., Lecithin.

Nitrogen bases :

• Carbon compounds with heterocyclic rings.
• Purine: Adenine, Guanine.       
• Pyrimidine: Cytosine, Uracil, Thymine.
• Nucleoside: Nitrogenous base + Sugar e.g., Adenosine, guanosine, thymidine Uridine and cytidine
• Nucleotide: Nitrogenous base + Sugar + Phosphate group. e.g., Adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid.
• Nucleic acid: Polymer of nucleotides - DNA and RNA.

PRIMARY AND SECONDARY METABOLITES :

• Primary metabolites :
  • Have identified function.
  • Play known roles in physiological function.
  • Carbohydrates, amino acids, fats and oils, nitrogen bases are the example of primary metabolites.
  
  
• Secondary metabolites :
  • Have no definite function.
  • Have no direct role in normal physiology.
  • Alkaloid, favonoides, rubber, essential oils, antibiotics, coloured pigments. Scents, gums, spices are some example.
  
  
• Biomacromolecules : Biomolecules with molecular weights in the range of ten thousand daltons and above; found in acid insoluble fraction.
• Lipids are not strictly macromolecules as their molecular weights do not exceed 800 Da but form a part of the acid insoluble pool.

Proteins :

• Are polymers of amino acids linked by peptide bond.
• Is a heteropolymer not homopolymer.
• Essential amino acids: those can’t be synthesized in our body, have to be supplied through our diet.
• Non-essential amino acids: our body can synthesize it from other sources.
• Collagen is the most abundant protein in animal.
• Ribulose bisphosphate Carboxylase-Oxygenase (RUBISCO) is most abundant protein in the whole biosphere.

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
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