Introduction

1. Introduction Lipids, Proteins, and Carbohydrates

2. Biochemistry • Biochem is the study of biological materials • Compounds of biological origin • Chemistry of biological processes • Biological materials are primarily made up of: • Lipids • Proteins • Carbohydrates

3. Lipids • Fat-like compounds that leave grease mark • Insoluble in water but soluble in organic solvents • Fats are esters, reacting alcohol & organic acid produces ester • Alcohol in fats is always glycerol, • The organic acid obtained from fats is called fatty acid

4. Fatty Acids • Mono-carboxylic acids, -COOH • Contain even number of H • Have long & straight Carbon chain (20) • Have 4 or less double bonds R1-COO-R1’ l R2-COO-R2’ A generic formula for a triglyceride l R3-COO-R3’

5. Oils • Veg oils are liquid at room temp. (low melt point) • VOs are less saturated than animal fats • Less saturated oils has greater number of C=C • Hydrogenation is adding H to C=C bonds to make the oil saturated (solid) • Degree of unsaturation is normally measured by the Iodine number. It is grams of Iodine that is decolorized by 100 grams of fat.

6. Hydrolyzing Fats • Hydrolyzing fats with inorganic bases is called saponification (yields glycerol & soap) • Sodium hydroxide makes hard soap and potassium hydroxide or ammonium hydroxide make soft soap. • Fats become rancid when exposed to moist air, microorganisms act as catalysts to hyrolyze the fat • Oxygen and ozone in the air oxidize the C=C bonds, producing aldehydes, acids, and peroxides that are the cause of rancid odor.

7. Waxes • Waxes that cover the fur and feather, and top of the shiny plant-leaf and beeswax are compound lipids that are also esters. • Waxes like paraffin are pure hydrocarbons and NOT fatsor esters.

8. Proteins

9. Introduction • Proteins make up our muscles, skin, and the biological catalysts called enzymes • Proteins do not accumulate in the body. • Excess proteins breaks down in the body and get excreted in the H2N-C-NH2 form of urea: ll O • We can manufacture protein through various bacteria

10. Protein Structure • Proteins are polymers • They are formed like strings of beads • Small units of protein chains is called amino acids • About 20 amino acids make up all known proteins • The amino acids have both amine group and the acid group attached to the same carbon atom (alpha amino acids)

11. Alpha amino acid structure Chemical Structure of a common amino acid: H l H2N-C-COOH ll R1 R1 is the organic “tail” of the amino acid

12. List of Amino Acids

13. Protein Polymers • Forming a protein’s polymer chain involves a condensation reaction between an acid group (-COOH) and an amine group (-NH2), with water as a product. • Structure of a 4 unit amino acid:

14. Polypeptide Chains • In a protein the polypeptide chain is the backbone of the molecule, holding it together by the covalent bonds (primary bonds) • Known protein polymers contain from a few dozen to half-a-million amino acid units • Proteins have a string-like secondary structure • Alpha helix structure -- Coiled peptide • Beta configuration ---- parallel strands • Combined structures-- coiled, parallel, and tangled sections

15. Hydrogen Bonds • Hydrogen bond form between O and N atoms • Alpha helix configuration is held in shape by H bonds between the C=O group on one loop and the N-H group across the way. • H bonds are fairly weak. Any external force that breaks these bonds simultaneously destroys the secondary structure, causing the protein to denature • For example heating and change in pH destroys H bond

16. Changing Proteins thru Other Bonds • Adding a substance that forms a stronger bond than H, it changes the shape of the protein. • For example Lead and Mercury in human body denatures many of the essential proteins in the body • Whole protein molecules cluster in a characteristic shape or structure. For example, tobacco mosaic virus molecules form a hollow tube • Proteins are somewhat water soluble and can be classified as precipitating colloids