3.2 Carbohydrates, lipids and proteins

IB Biology

Organic MoleculesOrganic Molecules

• What is organic?What is organic? CarbonCarbon-containing compounds in -containing compounds in

living thingsliving things Usually carbon Usually carbon covalentlycovalently

bonded to carbonbonded to carbon Also methane (CHAlso methane (CH44))

• What is inorganic?What is inorganic? ALL molecules ALL molecules without carbonwithout carbon ALSO carbon oxides, and ALSO carbon oxides, and

carbonatescarbonates Examples: COExamples: CO22, CO, H2CO, CO, H2CO33, ,

CaCOCaCO33

Structural formulas

• Show how all of the atoms in a compound are bound together

• Condensed structural formula has removed the bonds between other atoms like hydrogen

Condensed structural formula Structural formula

Macromolecules

• Large molecules made up of repeating subunits of smaller molecules called monomers

Macromolecule Monomer

Carbohydrate monosaccharides

Lipids fatty acids

Proteins amino acids

Nucleic acids nucleotides

CarbohydratesCarbohydrates

• All contain carbon, oxygen, and All contain carbon, oxygen, and hydrogenhydrogen

• Often have a Often have a ring structurering structure• Usually have the formula:Usually have the formula:

CCnnHH(2n)(2n)OOn Ratio of 2H:1On Ratio of 2H:1O

MonosaccharidesMonosaccharides

• Monomer (building block) of carbohydrates• Single sugars• Sweet taste

• Examples include: Fructose – gives sweet taste to many fruits,

attracting consumers that will spread the seeds Glucose – part of metabolism, transported

through the blood in animals to provide energy to cells

Galactose – in peas, and PART of lactose

Examples of Examples of monosaccharidesmonosaccharides

Glucose Fructose

Glucose Ribose Deoxyribose

DisaccharidesDisaccharides

• TwoTwo monosaccharides monosaccharides covalentlycovalently bonded: bonded:

+ =+ =

• Examples include:Examples include: Sucrose Sucrose (table sugar)(table sugar)

Transported for energy in plant Transported for energy in plant phloemphloem

LactoseLactose (in milk) (in milk) Provides energy for young animalsProvides energy for young animals

MaltoseMaltose (“malt” flavoring) (“malt” flavoring)

Condensation Condensation

• Join Join monomers monomers together together (creates a (creates a covalent bond)covalent bond)

• Creates a water Creates a water molecule molecule (loss of (loss of hydroxylhydroxyl (OH) (OH) from from one monomer and one monomer and hydrogenhydrogen (H) (H) from from the other)the other)

Condensation Condensation

• Join Join monomers monomers together together (creates a covalent (creates a covalent bond) bond) into a macromoleculeinto a macromolecule

• Monomer + monomer macromolecule + waterMonomer + monomer macromolecule + water

Hydrolysis Hydrolysis

• SplittingSplitting macromolecule macromolecule back into back into monomersmonomers

• Water is added to Water is added to the reactionthe reaction

Hydrolysis Hydrolysis

• SplittingSplitting macromolecule back into macromolecule back into monomersmonomers

• Water is added to the reactionWater is added to the reaction

Hydrolysis Hydrolysis

• SplittingSplitting macromolecule back into macromolecule back into monomersmonomers

• Water is added to the reactionWater is added to the reaction

• macromolecule + water monomer + monomermacromolecule + water monomer + monomer

PolysaccharidesPolysaccharides

• Many Many sugars sugars covalentlycovalently bonded together bonded together• Examples include:Examples include:

Chitin: used for strength and support in insect skeletons and fungal cell walls

Cellulose: forms fibers used for strength and support in plant cell walls

Glycogen: used for short-term energy storage in animals, found in muscles and liver

Starch: used for energy storage in plants

Polysaccharide examplesPolysaccharide examples

• ChitinChitin ==

• CelluloseCellulose ==

• GlycogenGlycogen ==

• StarchStarch ==

Lipids

LipidsLipids

• LipidsLipids - include steroids, waxes, fatty acids - include steroids, waxes, fatty acids and triglyceridesand triglycerides

• TriglycerideTriglyceride = 3 fatty acids + 1 glycerol = 3 fatty acids + 1 glycerol

= fat if = fat if solid solid at room temp.at room temp.

= oil if = oil if liquidliquid at room temp. at room temp. • Used in Used in energy storage, thermal insulation,

membrane structure, cell-to-cell membrane structure, cell-to-cell communication, buoyancy, and more.communication, buoyancy, and more.

LipidsLipids

• Two building blocks: Two building blocks: //

OHOH

Glycerol:CGlycerol:C33HH88OO33 Fatty acid:CHFatty acid:CH33-(CH-(CH22))xx-C=O-C=O

Condensation of glycerol Condensation of glycerol and fatty acidsand fatty acids

Forms a triglycerideForms a triglyceride

Energy StorageEnergy Storage

• LipidsLipids• ~9 Calories / gram ~9 Calories / gram

(twice as much (twice as much energy per gram)energy per gram)

• Long-term storageLong-term storage• Non-polar (water Non-polar (water

insoluble)insoluble)

• Carbohydrates• ~4 Calories / gram~4 Calories / gram• Short-term storageShort-term storage• Polar, water Polar, water

solublesoluble

Proteins

• Made up of amino acid monomers

• Over 20 amino acids with variable “R” group

• “R” group can be polar, non-polar, positively or negatively charged

Model an Amino Acid

Condensation of Amino Condensation of Amino Acids Acids

• Join Join amino acids together together (creates a (creates a covalent bond) covalent bond) in a peptide bond

Functions of Protein

• Two categories of proteins: Fibrous - elongated shape, tough,

insoluble in water Globular - compact/rounded shape,

water-soluble

• Functions: enzymes, hormones, transport, strength in tissue, defense against disease

Homework

• Pg. 52 #1-3

• Research: What is Splenda®? How does it’s molecular shape help it replace sugar?

Protein Structure - HL

• Structure determines biological activity of molecule

• Primary structure - polypeptide chain made up of amino acid sequence

• Secondary structure - due to the folding of polypeptide chains into -helix or -pleated sheets

Protein Structure

• Tertiary Structure - overall 3-D shape of protein due to interactions between R-groups of aa and with surrounding water medium

• Quaternary structure - the way polypeptides fit together when there is more than one chain