CHAPTER 3Molecules of Life

ORGANIC COMPOUNDS Always contain carbon Always have covalent bonds (not ionic) Usually associated with large numbers

of atoms Commonly associated with living things

CARBON Can covalently bond with as many as 4

other atoms Can form many shapes

CARBON COMPOUNDS

CARBON COMPOUNDS Carbohydrates Lipids Proteins Nucleic Acids

BUILDING COMPOUNDS Monomer—individual building unit Polymer—many units covalently bonded

BUILDING COMPOUNDS Functional groups—atoms or clusters of

atoms covalently bonded to organic compounds that affect the compound’s structure and fuction

REACTION CATEGORIES Mediated by enzymes (special proteins)

Fuctional-group transfer Electron transfer Rearrangement Condensation Cleavage

CONDENSATION Split OH- from one molecule Split H+ from another molecule Bonds form at exposed sites Water is byproduct

HYDROLYSIS Reverse of condensation Split molecules Add OH- and H+ from water

CARBOHYDRATES Monosaccharides

Single sugar unitSoluble in waterSweet tasteHydroxyl group (OH-)Used to assemble larger carbohydrates

CARBOHYDRATES Oligosaccharide

Short chain of two or more sugar monomersDisaccharide—2 units, simplest

CARBOHYDRATES Polysaccharide—chain of hundreds or

thousands of monomers “Complex” carbohydrates

Starch—plant energy sourceCellulose—plant cell wallGlycogen—animal muscle energyChitin—structural component of insects

LIPIDS Greasy or oily compounds Non-polar, hydrophobic Energy storage, membrane structure,

coatings

LIPIDS Fatty acids—long chain of mostly C and

H with a carboxyl group (-COOH) at the end

Saturated—single Carbon bonds Unsaturated—double Carbon bonds

LIPIDS Fat—one or more fatty acids attached to

glycerol Twice the energy of carbohydrates Insulation

LIPIDS Phospolipid

2 Fatty Acids + Phosphate Group + GlycerolMain structural material of membranes

LIPIDS Sterols

4 carbon rings, no fatty acid tailsCholesterol, testosterone, estrogen

LIPIDS Waxes

Long-chain fatty acids + alcohols or carbon rings

Coatings for plant parts or animal coverings

PROTEINS Most diverse of all biological molecules Enzymes Cell movement Storage & transport Hormones Antibodies Structure

PROTEINS Amino acid—monomer unit Three groups covalently bonded to

central C

PROTEINS Polypeptides—polymer of proteins

PROTEINS Structure

PrimarySecondaryTertiaryQuaternary

PROTEINS Why is structure important? Change in shape is VERY important to

function

NUCLEIC ACIDS Nucleotide—monomer unit

5-carbon sugar (ribose or deoxyribose)Nitrogen basePhosphate group

NUCLEIC ACID DNA—double-stranded helix, carries

hereditary information RNA—single-stranded helix, translates

code to build proteins ATP—single nucleotide, releases energy

for cells to work

DNA & RNA Large number of hydrogen bonds Nitrogen bases: Adenine, Cytosine,

Guanine, Thymine (Urasil)