1. Lipids, Proteins, and Carbohydrates
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
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 fats or 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 amino acid three letter code single letter code
serine
Ser S
threonine
Thr T
cysteine
Cys C
tyrosine
Tyr Y
asparagine
Asn N
glutamine
Gln Q
aspartic acid
Asp D
glutamic acid
Glu E
amino acid
three letter code
single letter code
glycine
Gly G
alanine
Ala A
valine
Val V
leucine
Leu L
isoleucine
Ile I
methionine
Met M
phenylalanine
Phe F
tryptophan
Trp W
proline
Pro P
lysine
Lys K
arginine
Arg R
histidine
His H

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