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 atoms4 valence electrons

Can form many shapes3-Dimensional shape is very important to

function

Carbohydrates Lipids Proteins Nucleic Acids

Monomer—individual building unitCarbohydrates—monosaccharidesLipids—fatty acidsProteins—amino acidsNucleic acids—nucleotides

Polymer—many units covalently bondedEach 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 transferChanges the chemical reactivity

Electron transferTransfers energy

RearrangementChanges internal bonds, changing 3D

structure Condensation

Combines two compounds by removing water

Dehydration synthesis Cleavage

Splits compounds with waterHydrolysis

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 = waterLysis = break,

destroy

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

MonosaccharidesSingle sugar unitGlucose, fructose, galactoseHydroxyl group (OH-) Isomers—same molecular formula (C6H12O6),

different structureUsed to assemble larger carbohydrates

DisaccharideShort chain of two sugar monomers

Formed by dehydration synthesisMaltose—Glucose + GlucoseSucrose—Glucose + FructoseLactose—Glucose + Galactose

Polysaccharide—chain of hundreds or thousands of monomersStraight or branched

“Complex” carbohydratesStarch—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 chainsCombined through dehydration synthesis

Phospolipid2 Fatty Acids + Phosphate Group + Glycerol

Similar to triglyceride but with phosphate group replacing a fatty acid chain

Main structural material of membranesHydrophilic “head”, hydrophobic “tail”

Sterols4 carbon rings, no fatty acid tailsCholesterol, testosterone, estrogen, other

hormonesSome regulate vitamin D functionRegulate cell membrane fluidity

WaxesLong-chain fatty acids + alcohols or carbon

ringsCoatings 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 proteinsPeptide bond, between C and N

Formed by dehydration synthesis

StructurePrimarySecondary

Pleated Sheet Alpha Helix

TertiaryQuaternary

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

functionSickle cell anemia due to a single amino acid

difference Denaturation—unraveling of polypeptide

chainsLoose shape, therefore also function

LipoproteinsBonded to fats

GlycoproteinsBonded to carbohydrates

Important to metabolism & heredity Nucleotide—monomer unit

5-carbon sugar (ribose or deoxyribose)Nitrogen base

Adenine, thymine, guanine, cytosine, uracilPhosphate 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