Understanding Biomolecules in Biology Class XI

1. BIOMOLECULES PREPARED BY S RATH PGT BIO K V III BBSR www.cbse123.co.cc BIOMOLECULES-CLASS XI BIOLOGY

2. Biomolecules of cells • All carbon compounds that are found in the living tissues are called Biomolecules. • Example-carbohydrate, fat, protein, amino acids, lipids etc. BIOMOLECULES-CLASS XI BIOLOGY

3. Classification of Biomolecules BIOMOLECULES-CLASS XI BIOLOGY

4. Amino acids • These are organic compounds which contain an amino group and an acidic group . • They are substituted methane with 4 substituent groups occupying the 4 valency positions of the carbon; these are hydrogen, carboxyl group, amino group & a variable group designated as R group. BIOMOLECULES-CLASS XI BIOLOGY

5. Amino acids • There are 20 amino acids occur in protein. • A specific characteristic property of amino acids is the ionizable nature of amino and carboxyl group, so the structure of amino acids changes in solutions of different pHs. BIOMOLECULES-CLASS XI BIOLOGY

6. Types of amino acids • Basic – lysine arginine • Acidic – glutamic acid aspartic acid • Neutral – alanine glycine valine • Aromatic – phenyl alanine , tyrosine, tryptophan BIOMOLECULES-CLASS XI BIOLOGY

7. Sugars • Simplest sugars are monosaccharides, which cannot be hydrolysed further composed of 3-7 carbon atoms. E.g. glyceraldehydes, ribose, glucose, fructose etc. • They have either free aldehyde or ketone group which reduce cupric ion to cuprous ion ,called reducing sugar. BIOMOLECULES-CLASS XI BIOLOGY

8. Sugars • Oligosaccharides may have two or a few monosaccharides. • Bond between two monosaccharides is called glycosidic bond. BIOMOLECULES-CLASS XI BIOLOGY

9. lipids BIOMOLECULES-CLASS XI BIOLOGY

10. Nucleotides • Organic compounds with heterocyclic rings. • A nucleotide consists of a nitrogenous base, a pentose sugar and a phosphate group. • A nucleoside has a nitrogenous base attached to a pentose sugar. • The nitrogenous bases are called adenine, guanine, thymine, cytosine and uracil • Polymerised nucleotides form DNA and RNA which are the genetic material. BIOMOLECULES-CLASS XI BIOLOGY

11. Primary and secondary metabolites • Metabolites may be primary or secondary type. • Primary metabolites have identifiable functions and play specific roles in the normal physiological processes. E.g. amino acids, nitrogenous bases, nucleic acids etc. • Secondary metabolites are products of certain metabolic pathways. E.g. pigments, rubber, gums, resins, carotenoids etc. BIOMOLECULES-CLASS XI BIOLOGY

12. Polysaccharides • These are a class of organic compounds (carbohydrates) which are long chain polymers of monosaccharides. • They are of two types: homopolysaccharides, heteropolysaccharides • Homopolysaccharides- cellulose, starch, inulin • Heteropolysaccharides- chitin BIOMOLECULES-CLASS XI BIOLOGY

13. Proteins • They are heteropolymers containing a string or strings of amino acids. • A peptide bond formed between the carboxyl group and the amino group of successive amino acids, joins the amino acids together. • Proteins result from the 20 amino acids , depending on the no.of amino acids and sequence of amino acids. • There are 4 levels of protein structure. BIOMOLECULES-CLASS XI BIOLOGY

14. Primary structure of protein • Protein exists as a long chain of amino acids arranged in a particular sequence. • It is nonfunctional. • Position of amino acid in a protein is obtain from this. • 1st a. a is called N-terminal and last is called C-terminal a. a. BIOMOLECULES-CLASS XI BIOLOGY

15. Secondary structure of protein • There is interaction between every fourth a. a by formation of hydrogen bond. The polypeptide has a helical shape. E.g. keratin. • Only right handed helix are formed. • If two or more chains are held together by intermolecular hydrogen bonds, the structure is called pleated sheet. E.g. silk fibres. BIOMOLECULES-CLASS XI BIOLOGY

16. Tertiary structure of protein • When a polypeptide chain becomes further stabilised by folding and coiling by the formation of ionic or hydrophobic bonds or disulphide bridges, the protein is said to be tertiary structure. • E.g. amylase, pepsin and other enzymes. BIOMOLECULES-CLASS XI BIOLOGY

17. Quaternary structure of protein • When a protein has many sub units, each having primary, sec. And tertiary st. of its own, the protein is said to be quaternary. • E.g. haemoglobin, insulin BIOMOLECULES-CLASS XI BIOLOGY

18. Enzymes • They are proteins that catalyse biochemical reaction, so called biocatalysts. • Specific for their substrate. • Each enzyme require a specific (optimum) pH & temp. • Accelerate a reaction by reducing the activation energy. BIOMOLECULES-CLASS XI BIOLOGY

19. Nomenclature of enzyme • Named by adding the suffix ‘ase’ to the substrate. E.g. sucrase • According to the physiological activity it catalyses. E.g. oxidase, dehydrogenase • The source from which they are obtained. E.g.papain from papaya. BIOMOLECULES-CLASS XI BIOLOGY

20. Classification of enzyme • Oxidoreductase • Transferase • Hydrolases • Lyases • Isomerasees • ligases BIOMOLECULES-CLASS XI BIOLOGY

21. Mechanism of enzyme action • Three dimensional structure of enzyme has one or more active site where the substrate binds. • Active site acts as ‘ lock’ into which substrate fits in like a ‘key’. • The point where substrate binds is called ‘substrate binding site’. • Substrate binding causes lowering of activation energy & reaction to proceed at a faster rate. • Binding of substrate induces the enzyme to alter its shape and fit more tightly. • Breaking of chemical bond of substrate and formation of E-P complex. • Enzyme releases product and free enzyme take up another molecule. BIOMOLECULES-CLASS XI BIOLOGY

22. Activation energy requirement BIOMOLECULES-CLASS XI BIOLOGY

23. Factors affecting enzyme action • Temperature • pH • Substrate concentration • chemicals BIOMOLECULES-CLASS XI BIOLOGY

24. Vmax velocity (s) Effect of substrate concentration BIOMOLECULES-CLASS XI BIOLOGY