The Molecules of Cells

 Always contain carbon  Always have covalent bonds (not ionic)  Usually associated with large numbers of atoms  Commonly associated with living things

 Can covalently bond with as many as 4 other atoms  4 valence electrons  Can form many shapes  3-Dimensional shape is very important to function

 Carbohydrates  Lipids  Proteins  Nucleic Acids

 Monomer—individual building unit  Carbohydrates—monosaccharides  Lipids—fatty acids  Proteins—amino acids  Nucleic acids—nucleotides  Polymer—many units covalently bonded  Each monomer is like a pearl on a necklace

 Functional groups—atoms or clusters of atoms covalently bonded to organic compounds that affect the compound’s structure and function

 Fuctional-group transfer  Changes the chemical reactivity  Electron transfer  Transfers energy  Rearrangement  Changes internal bonds, changing 3D structure  Condensation  Combines two compounds by removing water  Dehydration synthesis  Cleavage  Splits compounds with water  Hydrolysis

 Split OH - from one molecule  Split H + from another molecule  Bonds form at exposed sites  Water is byproduct  “Dehydration Synthesis”—Remove water (dehydrate) to combine/create (synthesize)

 Reverse of condensation  Split molecules  Add OH - and H + from water  Literally “water splitting”  Hydro = water  Lysis = break, destroy

 Contain C, H, and O in 1:2:1 ratio  Hydrophilic  Used for energy storage, structure

 Monosaccharides  Single sugar unit  Glucose, fructose, galactose  Hydroxyl group (OH - )  Isomers—same molecular formula (C 6 H 12 O 6 ), different structure  Used to assemble larger carbohydrates

 Disaccharide  Short chain of two sugar monomers Formed by dehydration synthesis  Maltose—Glucose + Glucose  Sucrose—Glucose + Fructose  Lactose—Glucose + Galactose

 Polysaccharide—chain of hundreds or thousands of monomers  Straight or branched  “Complex” carbohydrates  Starch—plant energy storage Easily converted to glucose Slightly- or unbranched  Cellulose—plant structural Cell wall Insoluble in water, indigestible  Glycogen—animal energy storage Stored in muscle & liver Highly branched  Chitin—structural component of insects

 Greasy or oily compounds  Non-polar, hydrophobic  Energy storage, membrane structure, coatings, insulation

 Fatty acids—long chain of mostly C and H with a carboxyl group (-COOH) at the end  Saturated—single Carbon bonds  “Saturated” with hydrogen (H + everywhere possible)  Unsaturated—double Carbon bonds  Some carbons don’t have max possible H +

 Fat—one or more fatty acids attached to glycerol  Twice the energy of carbohydrates  Triglycerides—95% of all fats  Glycerol + 3 Fatty Acid side chains  Combined through dehydration synthesis

 Phospolipid  2 Fatty Acids + Phosphate Group + Glycerol Similar to triglyceride but with phosphate group replacing a fatty acid chain  Main structural material of membranes  Hydrophilic “head”, hydrophobic “tail”

 Sterols  4 carbon rings, no fatty acid tails  Cholesterol, testosterone, estrogen, other hormones  Some regulate vitamin D function  Regulate cell membrane fluidity

 Waxes  Long-chain fatty acids + alcohols or carbon rings  Coatings for plant parts or animal coverings

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

 Amino acid—monomer unit  Three groups covalently bonded to central C  Same backbone, vary only in R group  20 amino acids necessary for life

 Polypeptides—polymer of proteins  Peptide bond, between C and N  Formed by dehydration synthesis

 Structure  Primary  Secondary  Pleated Sheet Alpha Helix  Tertiary  Quaternary  The shape of the structure determines function  Shape is determined by amino acids & hydrogen bonds  A single amino acid change will affect all the way to the quaternary structure

 Why is structure important?  Change in shape is VERY important to function  Sickle cell anemia due to a single amino acid difference  Denaturation—unraveling of polypeptide chains  Loose shape, therefore also function

 Lipoproteins  Bonded to fats  Glycoproteins  Bonded to carbohydrates

 Important to metabolism & heredity  Nucleotide—monomer unit  5-carbon sugar (ribose or deoxyribose)  Nitrogen base Adenine, thymine, guanine, cytosine, uracil  Phosphate group

 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