Structure and Function Structure and Function of Macromoleculesof Macromolecules

Chapter 5 Campbell and ReeseChapter 5 Campbell and Reese

Polymer Construction and Polymer Construction and DestructionDestruction

Dehydration synthesisDehydration synthesis Monomers put together with the loss of a HMonomers put together with the loss of a H22O O

molecule.molecule.

HydrolysisHydrolysis Polymers are broken apart by adding water.Polymers are broken apart by adding water.

Sugars are Aldehydes and Ketones

Glucose assumes a cyclic structure in aqueous solutions

MacromoleculesMacromolecules

Macromolecules are made up of smaller Macromolecules are made up of smaller molecules.molecules.

PolymersPolymers Long molecules of repeating identical or Long molecules of repeating identical or

repeating units.repeating units. Four major Classes of Biological polymers.Four major Classes of Biological polymers.

CarbohydratesCarbohydrates LipidsLipids ProteinsProteins Nucleic AcidsNucleic Acids

CarbohydratesCarbohydrates Monomers - MonosaccharideMonomers - Monosaccharide – – simple sugarssimple sugars

Glucose, fructose, galactoseGlucose, fructose, galactose Glucose is the ultimate source of fuel for animals.Glucose is the ultimate source of fuel for animals.

Polymers – PolysaccharidesPolymers – Polysaccharides For carbohydrates the repeating unit is glucose.For carbohydrates the repeating unit is glucose. The difference resides in the link between the glucose The difference resides in the link between the glucose

moleculesmolecules These are calledThese are called glycosidic linkagesglycosidic linkages

Types of PolysaccharidesTypes of Polysaccharides• Starch Starch

• Found in plants and are usually stored in roots.Found in plants and are usually stored in roots.• Fuel moleculesFuel molecules

• GlycogenGlycogen• Found in animals and stored in the liverFound in animals and stored in the liver• More compact than starch molecules.More compact than starch molecules.• Fuel molecules.Fuel molecules.

• CelluloseCellulose• Structural molecule found in plants Structural molecule found in plants

• Arranged in sturdy strandsArranged in sturdy strands• Found in plant cell wallsFound in plant cell walls

• Cannot be digested by humans because their enzymes cannot Cannot be digested by humans because their enzymes cannot recognize the beta 1-4 glycosidic linkage between glucose molecules.recognize the beta 1-4 glycosidic linkage between glucose molecules.

Chitin Chitin Structural molecule found in the shells of insectsStructural molecule found in the shells of insects Only carbohydrate that contains nitrogenOnly carbohydrate that contains nitrogen

Chitin

Starch the Storage Molecule

Cellulose is a Structural Molecule

Chitin is a Structural Molecule in Insects

LipidsLipids Lipids are composed of 1 to 3 fatty acid molecules and Lipids are composed of 1 to 3 fatty acid molecules and

one glycerol molecule.one glycerol molecule. Lipids are primarily hydrophobic due to the long chains Lipids are primarily hydrophobic due to the long chains

of non polar bonds within the hydrocarbon chain.of non polar bonds within the hydrocarbon chain. FunctionFunction

FuelsFuels Fatty acids are long hydrocarbon chains.Fatty acids are long hydrocarbon chains. The bond between the carbon and hydrogen atom contains a lot of The bond between the carbon and hydrogen atom contains a lot of

energy.energy. This is why fat molecules store a lot of energy.This is why fat molecules store a lot of energy.

The building blocks for to steroid hormones like testosterone and The building blocks for to steroid hormones like testosterone and estrogen.estrogen.

Cholesterol is a group of fused rings that serve as the foundation to Cholesterol is a group of fused rings that serve as the foundation to steroid hormonessteroid hormones

Cholesterol is also found in cell membranes and contribute to the fluid Cholesterol is also found in cell membranes and contribute to the fluid nature of a membrane.nature of a membrane.

Phospholipids are found in cell membranes.Phospholipids are found in cell membranes. InsulationInsulation

Adipose tissue used for padding and insulationAdipose tissue used for padding and insulation

Lipids Composed of Fatty Acids and Glycerol

Saturates Versus Unsaturated Lipids

SaturatedSaturated and and Non SaturatedNon Saturated LipidsLipids

Saturated LipidsSaturated Lipids SolidSolid

Comes from animals.Comes from animals. Lard and butterLard and butter

Have a single bond between all carbons within the fatty acid Have a single bond between all carbons within the fatty acid chain.chain.

Non Saturated LipidsNon Saturated Lipids OilsOils

Comes from plantsComes from plants Have a double bond between all carbons within the fatty acid Have a double bond between all carbons within the fatty acid

chain.chain.

Phospholipids Have a Hydrophilic and Hydrophobic End

Phospholipids and Hydrophobic Phospholipids and Hydrophobic InteractionsInteractions

Hydrophobic InteractionsHydrophobic Interactions Because lipids have a hydrophilic and hydrophobic Because lipids have a hydrophilic and hydrophobic

end the hydrophilic end of the molecule is attracted to end the hydrophilic end of the molecule is attracted to HH22O.O.

The hydrophobic tails face inward.The hydrophobic tails face inward. Because the hydrophobic tails are “hiding” from water Because the hydrophobic tails are “hiding” from water

they form structures such asthey form structures such as MicellesMicelles

Thought to have contributed to how the first cells were formed.Thought to have contributed to how the first cells were formed.

Lipid BilayersLipid Bilayers The basic structure pf membranesThe basic structure pf membranes

•

PhospholipidsPhospholipids

Cholesterol

ProteinsProteins MonomersMonomers

Amino acids also called peptidesAmino acids also called peptides Called amino acids because there is an amino group on one Called amino acids because there is an amino group on one

end and a carboxyl group on the other end.end and a carboxyl group on the other end. The carboxyl group donates protons to the amino group and The carboxyl group donates protons to the amino group and

there acts as an acid.there acts as an acid. All amino acids have the same basic structure and differ only All amino acids have the same basic structure and differ only

in their R groups.in their R groups.

PolymerPolymer PolypeptidePolypeptide Held together by peptide bonds.Held together by peptide bonds.

Proteins form very complex structuresProteins form very complex structures

Basic Structure of an Amino Acid

ProteinsProteins FunctionFunction

SupportSupport Connective tissue – tendonsConnective tissue – tendons SkinSkin AppendagesAppendages Feathers /hairFeathers /hair

StorageStorage Ovalbumin – egg whitesOvalbumin – egg whites

Nutrition for developing chick embryosNutrition for developing chick embryos SeedsSeeds

Protein stored for developing plant embryosProtein stored for developing plant embryos TransportTransport

HemoglobinHemoglobin Transport OTransport O22 in blood in blood

HormonesHormones EpinephrineEpinephrine

Fight or flight hormoneFight or flight hormone DefenseDefense

AntibodiesAntibodies MotilityMotility

FlagellaFlagella

Non Polar Amino Acids

Polar Amino Acids

Formation of the Peptide Bond

Levels of Protein Structure

• Primary Structure involves the order of the amino acids within the polypeptide chain.

• Secondary Structure is how the polypeptide chain folds back on itself.– Caused by hydrogen bonding

between an amino group of one amino acid and the carbonyl group of another within the polypeptide backbone.

– Two types• Alpha Helix• Beta Pleated Sheet

•

Tertiary Structure

Tertiary StructureTertiary Structure

R Groups bind togetherR Groups bind together Disulfide BridgesDisulfide Bridges Ionic BondsIonic Bonds Covalent BondsCovalent Bonds Hydrogen bondsHydrogen bonds

Hydrophobic side chains tend to endHydrophobic side chains tend to end up on the interior of the proteinup on the interior of the protein Hydrophilic groups tend to face the Hydrophilic groups tend to face the

exterior in aqueous environments.exterior in aqueous environments.

Quaternary Structure – More than one Polypeptide chain

Complex Proteins

• Typically have all four levels of structure.

DenaturationDenaturation

When hydrogen bonds within the protein’s When hydrogen bonds within the protein’s secondary, tertiary and quaternary secondary, tertiary and quaternary structure are disrupted the protein structure are disrupted the protein unravels.unravels.

Because shape affects the This affects the Because shape affects the This affects the function of the protein because the shape function of the protein because the shape of the protein determines its functionof the protein determines its function