Molecules of Life

Chapter 22

Great Idea:A cell’s major parts are constructed from a few

simple molecular building blocks

Chapter Outline

• Organic Molecules

• Proteins: The Workhorses of Life

• Carbohydrates

• Lipids

• Minerals and Vitamins

Organic Molecules

Four Basic Characteristics• Most molecules based on chemistry of carbon

– Organic molecules

• Life’s molecules form from few elements– H, O, C, N97.5% of body weight

• Molecules composed of simple building blocks– Arranged differently

• Shape determines behavior– Determines ability for bonding

Chemical Shorthand

• No H atoms or bonds to H are shown

• C atoms are not shown explicitlyShorthand

Proteins: The Workhorses of Life

Amino Acids: The Building Blocks of Proteins

• Amino Acid– Carboxyl group– Amino group– Carbon atom– Side group

Amino Acids: The Building Blocks of Proteins

• Side Group– Makes amino acid unique

Amino Acids cont.

• Bonding– Two amino acids

• H bonds with OH • Forms H2O • Forms peptide bond

– Polypeptide• chain

• Protein– Large molecule– Chain of amino acids

• Only 20 amino acids in living organisms

The Structure of Proteins

Proteins as Enzymes

• Enzymes– Specific shape & structure– Facilitates bonding

Proteins as Enzymes

How Drugs Work

• Blocking enzymes– Block active site– Molecules cannot bond– Reaction does not take place

• Shape of molecules– Block membrane transport– Block neurotransmitters

Carbohydrates

Carbohydrates

• Structure– C, H, O

• Simplest– Sugars

– CnH2nOn

• Monosaccharides

• Polysaccharide

• Starches

• Cellulose

Lipids

Lipids

• Lipids– Insoluble in water

• Role of lipids– Cell membranes

– Store energy

• Phospholipids– Make up cell

membrane

Saturated and Unsaturated Fats

• Saturated– C is fully bonded– Basis of cholesterol

• Unsaturated– Monounsaturated– Polyunsaturated

• hydrogenation

Lipids - molecules with large nonpolar areas soluble in nonpolar solvents:

A triglyceride is a fat or an oil. If the chain contains double bonds the fat is unsaturated.

Cholesterol - a steroidAn essential component of cell membraneMade from saturated fats

Like dissolves like. The lipids solubilize nonpolar substances in water.

Lipid bilayer - a component of the cell membrane

Cell Membranes

• Cell membrane– Hydrophilic– Hydrophobic

Minerals and Vitamins

Minerals

• Minerals– All chemical elements except C, H, N, O

• Example– Calcium

• 2% of weight

Vitamins

• Vitamins– Organic molecules– Must be taken in with food

• Except vitamin D

• Water soluble– Vitamins B & C

• Fat soluble– Vitamins A, D, E, & K

• Function– Assist enzymes