General Biology I ORGANIC CHEMISTRY AND CELLS Lecture 4

Organic molecules

Molecules containing Carbon and Hydrogen, abundant in living organisms.

Macromolecules

Carbohydrates, Lipids, Proteins, and Nucleic Acids.

Carbon

Element with 4 electrons in its outer shell, can form up to four bonds, can form nonpolar or polar bonds.

Water Solubility

Molecules with polar bonds are water soluble, while molecules with nonpolar bonds (like hydrocarbons) are not very water soluble.

Structural Isomers

Molecules with the same atoms but in different bonding relationships.

Stereoisomers

Molecules with identical bonding relationships but different spatial positioning of atoms.

Cis-trans Isomers

Isomers with different positioning around a double bond.

Enantiomers

Mirror image molecules.

Enzymes

Proteins that recognize one enantiomer but not the other.

Dehydration (Condensation) Reactions

Polymer formation by removing water molecules.

Hydrolysis Reactions

Breakdown of a polymer by adding water molecules.

Four Major Classes of Organic Molecules

Carbohydrates, Lipids, Proteins, and Nucleic Acids.

Carbohydrates

Contain Carbon, Hydrogen, and Oxygen in a 1:2:1 ratio, monomer is monosaccharide, examples include glucose and galactose.

Disaccharide

Two monosaccharides bonded together, examples include sucrose, maltose, and lactose.

Polysaccharide

Many monosaccharides bonded together, examples include starch, glycogen, cellulose, chitin, glycosaminoglycans, and peptidoglycan.

Lipids

Also known as fats, formed by bonding glycerol to 3 fatty acids, can be saturated or unsaturated.

Saturated Fatty Acids

All carbons have the maximal amount of hydrogens, tend to be solid at room temperature.

Unsaturated Fatty Acids

Contain one or more double bonds, tend to be liquid at room temperature, cis forms naturally, trans formed artificially.

Fats

Important for energy storage, can also be structural, providing cushioning and insulation.

Phospholipids

Make up the cell membrane, formed from glycerol, two fatty acids, and a phosphate group, amphipathic molecules with a polar head and nonpolar tail.

Steroids

Lipids with four interconnected rings of carbon atoms, usually insoluble in water, example:cholesterol.

Waxes

Lipids secreted onto the surface of plants and animals, very nonpolar, act as a barrier to water loss.