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Introduction. Lipids, Proteins, and Carbohydrates. 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. Lipids.

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Lipids, Proteins, and Carbohydrates


  • 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


  • 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

Fatty Acids

  • Mono-carboxylic acids, -COOH

  • Contain even number of H

  • Have long & straight Carbon chain (20)

  • Have 4 or less double bonds



    R2-COO-R2’ A generic formula for a triglyceride




  • 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.

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.


  • 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.



  • 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 theH2N-C-NH2

    form of urea: ll


  • We can manufacture protein through various bacteria

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)

Alpha amino acid structure

Chemical Structure of a common amino acid:






R1 is the organic “tail” of the amino acid

List of Amino Acids

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:

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

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

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

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