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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)