3-2: MOLECULES OF LIFE There are 4 classes of organic compounds essential to life: There are 4 classes of organic compounds essential to life: Carbohydrates.

3-2: MOLECULES OF 3-2: MOLECULES OF LIFELIFE There are 4 classes of organic There are 4 classes of organic

compounds essential to life:compounds essential to life: CarbohydratesCarbohydrates ProteinsProteins LipidsLipids Nucleic AcidsNucleic Acids

Each of these compounds are made up Each of these compounds are made up of C, H, + O atoms; but occur in of C, H, + O atoms; but occur in different ratiosdifferent ratios

CarbohydratesCarbohydrates Organic compounds composed of C, Organic compounds composed of C,

H, + OH, + O Found in ratios of 2H:1O; the # of C Found in ratios of 2H:1O; the # of C

variesvaries

Carbohydrates (cont.)Carbohydrates (cont.) MonosaccharidesMonosaccharides

Monomer – a simple sugar (1C:2H:1O ratio)Monomer – a simple sugar (1C:2H:1O ratio) Formula = (CHFormula = (CH22O)O)n n ; where n = 3-8; where n = 3-8 Common types:Common types:

GlucoseGlucose - - used in cells - - used in cells FructoseFructose - - found in fruits - - found in fruits GalactoseGalactose - - found in milk - - found in milk

All have same formula = All have same formula = CC66HH1212OO66

IsomersIsomers = same formula, different = same formula, different structuresstructures

ExamplesExamples

Carbohydrates (cont.)Carbohydrates (cont.)

Disaccharide – “double sugar” – Disaccharide – “double sugar” – combination of 2 monosaccharides combination of 2 monosaccharides from a condensation rxnfrom a condensation rxn Ex. SucroseEx. Sucrose

Carbohydrates (cont.)Carbohydrates (cont.)

Polysaccharide – complex molecules Polysaccharide – complex molecules composed of 3 or more composed of 3 or more monosaccharidesmonosaccharides In animals, glucose is stored as In animals, glucose is stored as

glycogenglycogen Found in branched chainsFound in branched chains Stored in liver + musclesStored in liver + muscles

Carbohydrates (cont.)Carbohydrates (cont.) In plants, glucose is stored as In plants, glucose is stored as

starchstarch or or cellulosecellulose StarchStarch – found as branched or – found as branched or

unbranched chainsunbranched chains CelluloseCellulose – gives strength + rigidity to – gives strength + rigidity to

plant cell wallsplant cell walls

ProteinsProteins

Organic compounds composed Organic compounds composed mainly of C, H, O, + mainly of C, H, O, + NN Formed from monomersFormed from monomers Found in skin, hair, nails + musclesFound in skin, hair, nails + muscles

Proteins (cont.)Proteins (cont.) Amino Acids (AA)Amino Acids (AA)

Building blocks of proteins – monomerBuilding blocks of proteins – monomer 20 different AA in living things20 different AA in living things Difference = Difference = functional groups functional groups

attached to Cattached to C R. Groups R. Groups can be simple or complexcan be simple or complex Can take on a variety of shapes, thus Can take on a variety of shapes, thus

carrying out different activities in living carrying out different activities in living thingsthings

Dipeptide – the bonding of 2 AAsDipeptide – the bonding of 2 AAs Forms a peptide bondForms a peptide bond

Proteins (cont.)Proteins (cont.)

Polypeptide – a long chain of AA’sPolypeptide – a long chain of AA’s Chain folds or bends based on certain Chain folds or bends based on certain

conditions ( i.e. Temperature conditions ( i.e. Temperature increase/decrease) – ex. eggincrease/decrease) – ex. egg

When polypeptide folds, takes on a When polypeptide folds, takes on a globular shapeglobular shape

Proteins (cont.)Proteins (cont.)

EnzymesEnzymes RNA or protein molecules that act as RNA or protein molecules that act as

biological catalystsbiological catalysts Work by a “lock-and-key” method with its Work by a “lock-and-key” method with its

substrate – the reactant being catalyzed– the reactant being catalyzed Substrate will only “fit” if shape of Substrate will only “fit” if shape of active active

site site is a matchis a match Once enzyme is done, it releases the Once enzyme is done, it releases the

product(s) and can be used over + over product(s) and can be used over + over againagain

Mail fail to work if environment changes Mail fail to work if environment changes (temp or pH)(temp or pH)

Proteins (cont.)Proteins (cont.)

How an enzyme works…How an enzyme works…

LipidsLipids Large, nonpolar organic molecules Large, nonpolar organic molecules

that that do not dissolve in waterdo not dissolve in water Higher ratio of C + H atoms to O atomsHigher ratio of C + H atoms to O atoms C-H bonding (stores more C-H bonding (stores more nrgnrg))

Lipids (cont.)Lipids (cont.)

Fatty acids – monomer of a lipid – Fatty acids – monomer of a lipid – unbranched chainsunbranched chains Contain a Contain a carboxyl groupcarboxyl group, -, -COOHCOOH, ,

at one endat one end Hydrophilic end Hydrophilic end – attracted to water – attracted to water

(polar)(polar) Hydrocarbon at other endHydrocarbon at other end

Hydrophobic end Hydrophobic end – “afraid” of water – “afraid” of water (nonpolar)(nonpolar)

Saturated vs. Saturated vs. UnsaturatedUnsaturated

Saturated – all C atoms are “full”Saturated – all C atoms are “full” Unsaturated – has double bond(s) Unsaturated – has double bond(s)

between C atomsbetween C atoms

Lipids (cont.)Lipids (cont.) TriglycerideTriglyceride – 3 fatty acid – 3 fatty acid

molecules + glycerolmolecules + glycerol Functions:Functions:

NRG, insulation + protection, NRG, insulation + protection, nutrition (vitamins ares stored in fats nutrition (vitamins ares stored in fats in body)in body)

Types:Types: Saturated Saturated

High melting point, solid @ room temp.High melting point, solid @ room temp. Examples: shortening (Crisco), animal Examples: shortening (Crisco), animal

fatsfats UnsaturatedUnsaturated

Low melting point, liquid @ room temp.Low melting point, liquid @ room temp. Examples: plant seed oils, fruitsExamples: plant seed oils, fruits

PhospholipidsPhospholipids – 2 fatty acid – 2 fatty acid molecules + glycerolmolecules + glycerol Forms lipid bilayer for cell membranesForms lipid bilayer for cell membranes

Lipids (cont.)Lipids (cont.)

WaxWax – long fatty acid chain + long – long fatty acid chain + long chain of alcoholchain of alcohol Highly waterproofHighly waterproof Used as a protective coatingUsed as a protective coating

Lipids (cont.)Lipids (cont.)

SteroidsSteroids – molecules of 4 fused C- – molecules of 4 fused C-rings with different functional rings with different functional groupsgroups Common types:Common types:

Hormones – testosteroneHormones – testosterone Cholesterol – needed by nerves + cellsCholesterol – needed by nerves + cells

Lipids (cont.)Lipids (cont.)

Nucleic AcidsNucleic Acids Very large, complex organic molecules Very large, complex organic molecules

that store important information in cellsthat store important information in cells Two types:Two types:

DNA DNA – – deoxyribonucleic acid – determines deoxyribonucleic acid – determines characteristics of organism and directs cells characteristics of organism and directs cells activitiesactivities

RNARNA – ribonucleic acid – ribonucleic acid Stores + transfers info. essential to make Stores + transfers info. essential to make

proteinsproteins Can also act as an enzymeCan also act as an enzyme

NucleotidesNucleotides – monomers of Nucleic Acid – monomers of Nucleic Acid 5-C sugar5-C sugar Phosphate groupPhosphate group Nitrogen-baseNitrogen-base

What a nucleotide looks What a nucleotide looks like…like…

DNA vs. RNADNA vs. RNA