3.2 carbohydrates, lipids and proteins ib biology
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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