Biological Molecules

BIO 101

Dr. D. L. Daley


Molecules made of carbon - “Organic Chemistry”

Most are large - macromolecules




Nucleic Acids

Synthesis of Macromolecules

Complex organic molecules are produced from smaller subunits

These subunits are termed monomers

Long chains of these monomers are termed polymers

Dehydration  Synthesis

When two smaller monomers are joined together to create larger biological molecules water is a by-product

Dehydration synthesis

A hydrogen ion (H+) is removed from one subunit and a hydroxyl ion (OH-) is removed from the other - water is formed

The two subunits which loss the H+ and OH- have openings in their outer electron shells and the openings are filled when they create a covalent bond


The reverse reaction of dehydration synthesis is “hydrolysis”

Hydrolysis splits a larger macromolecule into two subunits

This is the way our digestive enzymes breakdown the food we ingest


Compounds of carbon, hydrogen and oxygen

Carbohydrates composed of one sugar are called monosaccharides

Two monosaccharides linked together form a disaccharide

Larger carbohydrates (polysaccharide) created by linking several monosaccharides

Monosaccharides are usually 3 to 7 carbons long

Glucose - most common sugar in living organisms - 6 carbon sugar

Synthesis of a Disaccharide




Starch and Cellulose

Polysaccharides of plants

Starch - like glycogen but not as highly branched

Source of glucose in our diets

Cellulose - structural compound in plants

cannot be digested - called fiber


Animal starch

Highly branched polymer of glucose

Glucose is converted in the liver to glycogen


The outer coverings of insects, crabs and spiders is composed of chitin

The walls of many fungi are reinforced with chitin

Chitin is polysaccharide of glucose subunits that bear a nitrogen containing functional group



Contain large regions composed almost entirely of hydrogen and carbon with non-polar carbon-carbon or carbon-hydrogen bonds

These sections are hydrophobic and thus insoluble in water

Three classes

Oils, fats and waxes

Phospholipids - similar to oils but contain phosphorous and nitrogen

Fused ring family of steroids

Oils, Fats and Waxes

Triglyceride or fat


Three fatty acids - hydrocarbon chains with carboxyl group

Fats and Oils








Cholesterol & Steroid Hormones







Composed of amino acids

Form long chains

May have structural function

e.g. keratin- nails and hair

Connective tissue - tendons and ligaments

Allow muscles to contract (actin and myosin)

Another role - enzymes

Catalysts - speed up chemical reactions

Amino Acids

Two functional groups

Amino group  --  (-NH2)

Carboxyl  group (-COOH)

Protein Synthesis




Levels of Proteins Structure





Nucleic Acids

Long chains of similar subunits called nucleotide

DNA and RNA are nucleic acids

DNA is the molecule that contains the genetic information to construct all the proteins of the cell

RNA is copied from DNA and carries the genetic code to the structures involved in protein synthesis


Complex of three unit molecules


5 carbon sugar

DNA - Deoxyribose
RNA - Ribose

Nitrogen containing base

DNA Bases




Nuclei Acids



DNA Replication




Adenosine Triphosphate (ATP)





3 Phosphate groups

High Energy molecule

Phosphate bonds broken - energy released

Called “Energy Currency” of Cells