The Structure and The Structure and Function of Function of

MacromoleculesMacromoleculesChapter 5Chapter 5

1 -- carbohydrates1 -- carbohydrates

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Macromolecules: Macromolecules: The Molecules of LifeThe Molecules of Life

Three of the four classes of life’s organic Three of the four classes of life’s organic molecules are polymers:molecules are polymers: CarbohydratesCarbohydrates ProteinsProteins Nucleic acidsNucleic acids

Lipids are not polymers, just large Lipids are not polymers, just large moleculesmolecules

Nucleic Acids and Carbohydrates -- Nucleic Acids and Carbohydrates -- both monomers & polymersboth monomers & polymers

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The Synthesis and The Synthesis and Breakdown of PolymersBreakdown of Polymers

Monomers form polymers by condensation Monomers form polymers by condensation (or dehydration) reactions(or dehydration) reactions

Polymers are disassembled to monomers Polymers are disassembled to monomers by hydrolysisby hydrolysis

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Macromolecules: Macromolecules: The Molecules of LifeThe Molecules of Life

CarbohydratesCarbohydrates Nucleic AcidsNucleic Acids ProteinsProteins LipidsLipids

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Carbohydrates – sugars Carbohydrates – sugars and polymers of sugarsand polymers of sugars

Monosaccharides -- single sugarsMonosaccharides -- single sugars Disaccharides – two sugarsDisaccharides – two sugars Oligosaccharides -- three to nine sugarsOligosaccharides -- three to nine sugars Polysaccharides -- many sugar building Polysaccharides -- many sugar building

blocksblocks

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SugarsSugars

Monosaccharides -- CHMonosaccharides -- CH22OO Glucose -- most commonGlucose -- most common Classified by location of carbonyl group Classified by location of carbonyl group

and number of carbons in skeletonand number of carbons in skeleton

LE 5-3LE 5-3Triose sugars

(C3H6O3)

GlyceraldehydeAld

ose

sK

eto

s es

Pentose sugars(C5H10O5)

Ribose

Hexose sugars(C5H12O6)

Glucose Galactose

Dihydroxyacetone

Ribulose

Fructose

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Though often drawn Though often drawn as a linear skeleton, as a linear skeleton, in aqueous solutions in aqueous solutions

they form ringsthey form rings

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glucose

12glucose

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Formed when a dehydration Formed when a dehydration reaction joins two shorter reaction joins two shorter saccharides saccharides Bond -- glycosidic linkageBond -- glycosidic linkage

Disaccharides to Disaccharides to PolysaccharidesPolysaccharides

Glucose

Maltose

Fructose Sucrose

Glucose Glucose

Dehydrationreaction in thesynthesis of maltose

Dehydrationreaction in thesynthesis of sucrose

1–4glycosidic

linkage

1–2glycosidic

linkage

Between hydroxyl in one monomer Between hydroxyl in one monomer and hydroxyl in another (e.g., 1-4 in and hydroxyl in another (e.g., 1-4 in Maltose; 1-2 in Sucrose)Maltose; 1-2 in Sucrose)

Glucose

Maltose

Fructose Sucrose

Glucose Glucose

Dehydrationreaction in thesynthesis of maltose

Dehydrationreaction in thesynthesis of sucrose

1–4glycosidic

linkage

1–2glycosidic

linkage

Glycoside LinkageGlycoside Linkage

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Glycoside LinkageGlycoside LinkageTwo ring forms: alpha (Two ring forms: alpha () and beta () and beta ())

Note: Note: glucose == galactose ….. glucose == galactose …..

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Glycoside LinkageGlycoside LinkageBetween hydroxyl in one Between hydroxyl in one

monomer and hydroxyl in monomer and hydroxyl in anotheranother Maltose (malt sugar) = glucose + Maltose (malt sugar) = glucose +

glucoseglucose Lactose (milk sugar) = glucose + Lactose (milk sugar) = glucose +

galactosegalactose

http://stefan101blog.wordpress.com/2013/03/20/glycosidic-linkage-in-carbohydrates

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Glucose

Maltose

Fructose Sucrose

Glucose Glucose

Dehydrationreaction in thesynthesis of maltose

Dehydrationreaction in thesynthesis of sucrose

1–4glycosidic

linkage

1–2glycosidic

linkage

COMMON DISACCHARIDES:COMMON DISACCHARIDES:Sucrose (table sugar) = glucose + Sucrose (table sugar) = glucose +

fructosefructoseMaltose (malt sugar) = glucose + Maltose (malt sugar) = glucose +

glucoseglucoseLactose (milk sugar) = glucose + Lactose (milk sugar) = glucose +

galactosegalactose

OligosaccharidesOligosaccharides

Typically short chains (3-9)Typically short chains (3-9) Fructose and Galactose most common Fructose and Galactose most common

monomersmonomers Often chemical markersOften chemical markers

ABO blood typeABO blood type Therapeutic to the gut floraTherapeutic to the gut flora Believed to play a part in Believed to play a part in

fertilizationfertilization

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PolysaccharPolysaccharideide

Structure and Structure and function -- function -- determined by determined by monomers and monomers and positions of positions of glycosidic glycosidic linkageslinkages

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Carbohydrates serve as Carbohydrates serve as fuel and building materialfuel and building material

SourceSource ---- cellular respiration cellular respiration Storage -- Storage -- polysaccharidespolysaccharides Structural components -- Structural components -- cell walls, cell walls,

microfibrils, chitinmicrofibrils, chitin

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e

Cellular RespirationCellular Respiration and Photosynthesis and Photosynthesis

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RESPIRATIONRESPIRATION

C6H12O6 + O2 CO2 + H2O + ENERGY

ATP

686 kcal/mole (180 grams)

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Pyruvate

Glucose

CYTOSOL

No O2 presentFermentation or Anaerobic respiration

Ethanolor

lactate

Acetyl CoA

MITOCHONDRION

O2 present -- Aerobic cellular respiration

Citricacidcycle

Glycolysis …. What Glycolysis …. What next?next?

Glycolysis

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Photosynthesis Photosynthesis Summarized Summarized

6 CO2 + 12 H2O + Light energy C6H12O6 + 6 O2 + 6 H2 O

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ChloroplastChloroplast Gelatinous matrix called the stroma Contains prokaryotic ribosomes,

DNA Carbohydrate synthesis occurs in

the stroma Folded membranes called thylakoids fill the stroma and form into stacks called grana

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H2O

LIGHTREACTIONS

Chloroplast

Light

ATP

NADPH

O2

Light reactions (in the thylakoids) -- split water, release O2, produce ATP, and form NADPH

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H2O

LIGHTREACTIONS

Chloroplast

Light

ATP

NADPH

O2

NADP+

CO2

ADPP+ i

CALVINCYCLE

[CH2O](sugar)

The Calvin cycle (in the stroma) -- forms sugar from CO2, using ATP and NADPH

Respiration & Respiration & PhotosynthesisPhotosynthesis

Respiration Respiration

CC66HH1212OO66 + O + O22 CO CO22 + H + H22O + ENERGYO + ENERGY

PhotosynthesisPhotosynthesis

COCO22 + H + H22O O C C66HH1212OO66 + O + O22 + H + H22 O O

Light energy Light energy

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Storage PolysaccharidesStorage Polysaccharides

Plants store Plants store surplus starch surplus starch as granules as granules within within chloroplasts, chloroplasts, leukoplasts, leukoplasts, and other and other plastids plastids

Chloroplast Starch

1 µm

Amylose

Starch: a plant polysaccharide

Amylopectin

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Glycogen is the Glycogen is the storage storage polysaccharide polysaccharide in animalsin animals

Humans and Humans and other other vertebrates vertebrates store glycogen store glycogen mainly in liver mainly in liver and muscle and muscle cellscells

Storage PolysaccharidesStorage PolysaccharidesMitochondriaGlycogen granules

0.5 µm

Glycogen

Glycogen: an animal polysaccharide

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Structural Structural PolysaccharidesPolysaccharides

Cellulose -- plant cell wallsCellulose -- plant cell walls Chitin -- cellulose-ishChitin -- cellulose-ish

Polymers of glucose – different glycosidic Polymers of glucose – different glycosidic linkageslinkages alpha glucose – helicalalpha glucose – helical beta glucose -- straightbeta glucose -- straight

In In ββ glucose glucose -- hydrogen bonds form between strands-- hydrogen bonds form between strandsstrands group into microfibrils -- strong building strands group into microfibrils -- strong building

materials for plantsmaterials for plants

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Cellulosemolecules

Cellulose microfibrilsin a plant cell wall

Cell walls Microfibril

Plant cells

0.5 µm

Glucosemonomer

Cellulose vs StarchCellulose vs Starch

Enzymes that digest starch by Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulosehydrolyze beta linkages in cellulose

Cellulose in human food -- insoluble Cellulose in human food -- insoluble fiberfiber

Some microbes use enzymes to digest Some microbes use enzymes to digest cellulosecellulose

Many herbivores, from cows to Many herbivores, from cows to termites, have symbiotic relationships termites, have symbiotic relationships with these microbeswith these microbes

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ChitinChitin

exoskeleton of arthropodsexoskeleton of arthropods primary component of cell walls in fungiprimary component of cell walls in fungi structurally – similar to cellulosestructurally – similar to cellulose functionally – similar to protein keratinfunctionally – similar to protein keratin

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SucraloseSucralose

Sucrose

SucraloseCl

Cl

Cl

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Stevia

Steviol

Stevioside

AspartameAspartame Aspartame is a methyl ester of Aspartame is a methyl ester of

aspartic acid and phenylalanine (2 aspartic acid and phenylalanine (2 amino acids).amino acids).

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SaccharineSaccharine

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