The Molecules of LifeThe Molecules of Life

All depend on mainly a handful of elements, namely:

H O C N S P Hydrogen, Oxygen, Carbon Nitrogen Sulfur Phosphorus

in proteins in nucleic acids

The basis of every organic substance

Why Carbon?Why Carbon?

• Four outer electrons

• Makes up to four bonds

• Least electronegative non-metal

• High affinity for H & O

Why Carbon?Why Carbon?

• Those four bonds can be arranged in space in various ways: tetrahedral, planar; as single, double or triple bonds.

• Carbon bonds are strong enough for even very large molecules; they are covalent bonds.

OxygenOxygen• Six outer

electrons• Makes up to two

bonds• Highly

electronegative non-metal

• High affinity for electrons = polar covalent bonds

Types of BondsTypes of Bonds

• Unequal sharing of electrons

• An intra-molecular force

• Transfer of electrons between a metal atom & a non-metal atom

• Attraction between H in one molecule and O, S, or N in another

• An inter-molecular force

• Equal sharing of electrons

• An intra-molecular force

Functional GroupsFunctional Groups

• Arrangements of atoms that confer specific properties to a molecule, help us identify a type of molecule, or predict reactions.

• Hydroxyl = alcohols• Amino = amino acids, proteins • Ester = in DNA & RNA• Carbonyl = in simple carbohydrates• Ether = in some simple sugars

Functional GroupsFunctional Groups

Can you identify the functional groups?

Ethanol

Ritalin

Theobromine (in chocolate)

Caffeine

Capsaicin(in hot peppers)

CarbohydratesCarbohydrates• C, H, and O in a 1:2:1

Ratio

• Monosaccharides (simple sugars)

• Glucose, Fructose & Galactose

• Disaccharides (double sugars)

• Glucose + Glucose = Maltose

• Glucose + Fructose = Sucrose

• Glucose + Galactose = Lactose

• Formed by dehydration synthesis reactions

Glucose

Fructose

Galactose

Sucrose

CarbohydratesCarbohydrates• Polysaccharides (starches)• Sugars are the building blocks, or monomers, of

starches.• Because they’re made of many repeating units, starches

are considered polymers.

CarbohydratesCarbohydrates• Sugars = quick energy;

starches = storage, slower energy

• In animals, the storage starch is Glycogen (branching)

• In plants, the structural starch is Cellulose (straight chain); storage is Amylose.

Glycogen

LipidsLipids• Fats & Oils• C, H, O in no specific

ratio

• Simple fat = 1 molecule of glycerol + 3 molecules of fatty acid

• Fatty acids are either saturated (all single bonds, C-C) or unsaturated (have double C=C bonds, or triple bonds)

• Also formed by dehydration synthesis & digested by hydrolysis.

LipidsLipids• Replace one fatty acid

with a phosphate group (PO4) and you get a phospholipid, the crucial component of any cell membrane.

• Very important property is that they’re amphoteric; that is, part of the molecule mixes with water (it’s polar) and another part doesn’t (nonpolar)

• Hydrophobic vs. Hydrophilic

• Most lipids are hydrophobic only.

Bilayer

LipidsLipids • Because they’re amphoteric, they interact with water in a specific way:

Heads like waterTails fear water

• Hydrophilic heads arrange themselves facing water; Hydrophobic tails arrange themselves facing one another

• Solid micelles• Hollow liposomes• Large bilayers

LipidsLipids

• These hydrophobic – hydrophilic interactions are how detergents & soaps work: they’re amphoteric, too!

• Dirt & grime tend to be nonpolar, or oily; the detergent molecule’s tails grab dirt and pull it away.

LipidsLipids

• Get enough phospholipids together, stick in some proteins & other molecules, and you get a cell membrane

• (more about these soon!)

LipidsLipids

• A special category of lipid are the sterols. • Best known one is cholesterol, a component of cell membranes & vital for the production of

steroid hormones.

ProteinsProteinsAlso called Polypeptides • C, H, O, but also N, S• Amino Acids are the

monomers of proteins• AA are held together by a

peptide bond.• Very large, very complex

molecules.

Many different types:

• Structural• Enzymes• Cell identity, adhesion• Receptors• Hormones

ProteinsProteins

ProteinsProteinsFour levels of structure:

• Primary 1o = chain of amino acids

• Secondary 2o = twist or fold that chain ( helix, pleat)

• Tertiary 3o = Fold it on itself again (held together by H-bonds)

• Quaternary 4o = Put two or more 3o structures together.

ProteinsProteinsTo remember their roles:

“Proteins are TEACHERS”

• TRANSPORT

• ENZYMES

• ANTIBODIES & ANTIGENS

• CONTRACTILE

• HORMONES

• EXTRA STORAGE

• RECEPTORS

• STRUCTURE

ProteinsProteinsTo remember their roles:

“Proteins are TEACHERS”

• TRANSPORT

• ENZYMES

• ANTIBODIES & ANTIGENS

• CONTRACTILE

• HORMONES

• EXTRA STORAGE

• RECEPTORS

• STRUCTURE

Dehydration SynthesisDehydration Synthesis& Hydrolysis& Hydrolysis

All of these macromolecules are made by dehydration synthesis reactions

- These are reactions where H + OH are removed from two molecules, forming H20 & create a bond.

- Also called Condensation reactions

When they are broken down, this happens by adding H + OH to a bond, breaking it. It’s like using water to break a bond.

- Water = hydro- Breaking = lysis- Hydrolysis Reaction

Making Sucrose

Breaking Sucrose

Can you identify these?Can you identify these?