organic macromolecules

Organic Macromolecules

MacromoleculesSmaller organic molecules join

together to form larger moleculesmacromolecules

4 major classes of macromolecules:carbohydrateslipidsproteinsnucleic acids

PolymersLong molecules covalently bonded by linking

chains of repeating smaller units polymers monomers = repeated small units each cell has millionsof diff macromoleculesThink: 26 letters of alphabet for all possiblecombinations

How to break down a polymerHydrolysis

use H2O to break apart monomers reverse of condensation reactionH2O is split into H and OHH & OH group attach where the

covalent bond used to beex: digestion is

hydrolysis

http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

So what’s all this talk about carbs??Atkin’s Diet & South Beach Diet

Carbohydrates

1. contain C, H, O2. 1:2:1 ratio3. provide energy or storage4. many end in “ose”5. three main groups – monosaccharides, disaccharides, polysaccharides

CarbohydratesCarbohydrates are composed of C, H, O

carbo - hydr - ateCH2O

(CH2O)x C6H12O6

Function:energy u energy storageraw materials u structural materials

Monomer: single sugar molecules (monosaccharides)

ex: sugars & starches

Sugars Most names for sugars end in -ose

Classified by number of carbons6C = hexose (glucose)5C = pentose (fructose, ribose)

3C = triose (glyceraldehyde): imp intermediate in metabolic process of cell respiration (burning glucose for energy)

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What functional groups?

carbonyl

ketone

aldehyde

hydroxyl

Sugar structure5C & 6C sugars form rings in aqueous

solutions in cells!

Carbons are numbered

Numbered carbons

C

CC

C

CC

1'

2'3'

4'

5'6'

O

Simple & complex sugarsMonosaccharides

simple 1 monomer sugarsglucose

Disaccharides2 monomerssucrose

Polysaccharides large polymersstarch

a. Monosaccharides: simplest form of carbohydrates building blocks for larger carbohydrates

(also called monomers) usually contain molecular formula

C6H12O6

isomers: glucose, fructose, galactose glucose (blood sugar), fructose &

galactose (fruit sugars) can occur as straight (open) chains or

as rings numbering of carbon atoms in ring

depends on the straight chain (always # the carbon atoms so that the carbon attached to the functional group is the smallest number possible)

Glucose in the open chain and ring form

Building sugarsDehydration synthesis: putting together

monomers by taking out water (req’s energy & enzymes)

|fructose

|glucose

glycosidic linkage: can be alpha or beta which changes the orientation of the 2 monosaccharides to each other

monosaccharides disaccharide

|sucrose

structural isomers

“Let’s go to the video tape!”(play movie here)

Isomers of Glucose

Lactose: β-1,4 linkage (the 1,4 tells you where the 2 molecules are bonded to each other)

b. Disaccharides: C12H22O11 (molecular formula) 2 monosaccharides joined twice the energy sucrose (table sugar) = 1 glucose + 1

fructose maltose (found in sugar cane) =

1 glucose + 1 glucose lactose (milk sugar) = 1 glucose + 1

galactose maltose has alpha linkage (bottom to

bottom) sucrose has alpha linkage (bottom to

bottom) lactose has beta linkage (top to bottom) 1,4 or 1,2 numbering tells you what

carbon numbers the linkage is being formed at

Polysaccharides (polymers of hundreds to thousands of monosaccharides)

Polymers of sugars costs little energy to buildeasily reversible = release

energyFunction:

energy storage starch (plants)glycogen (animals)

building materials = structurecellulose (plants)chitin (arthropods & fungi)

c. Polysaccharides: (C6H10O5)n [molecular formula] N= 5-5,000 monosaccharides Form chains of polymers

(repeating monomer units) 2 main functions: food storage and

structure Food storage

Structure

cellulosechitin

plant starches animal starches

amylose amylopectin glycogen

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Branched v linear polysaccharides(made of repeating glucose monomers) Q: can you see the difference between starch & glycogen? Which is easier to digest?

Glycogen

α -1,4 linkage on the straight chain α -1,6 linkage at the branch points (every 10 glucose molecules)

Polysaccharide diversity

Molecular structure determines function

isomers of glucose How does structure influence

function…

Amylose v Amylopectin

Amylose: straight chain with α -1,4 linkageAmylopectin: - α -1,4 linkage on the straight chain with α -1,6 linkage at the branch points (every 30 glucose molecules)

Comparison of Cellulose vs. Amylose

Amylose straight chain that

forms a helical structure in water

uses α glucose α-1,4 linkage used for storage

(starch) in plants soluble in water Cellulose straight chain uses β glucose β-1,4 linkage (every

other glucose subunit is inverted)

cannot be digested by animals (lack the enzyme cellulase)

used for support makes up plant cell

walls insoluble in water

Cellulose in Plant Cell Walls

Parallel cellulose molecules are held together by hydrogen bonds.

Cellulose Most abundant

organic compound on Earth

Cross-linking between

polysaccharidechains: rigid & hard to digestThink herbivores:

spend a lot of time digesting food w/help of microbes

Digesting starch vs. cellulose (starch: all the glycosidic linkages are on same side: molecule lies flat)

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Cowcan digest cellulose well; no need to eat supplemental sugars

Gorillacan’t digest cellulose well; must supplement with sugar source, like fruit

Chitinforms the

exoskeletons of arthropods

used to make a strong and flexible surgical thread that decomposes after the wound or incision heals

makes up the cell walls of some fungiThe structure of the chitin monomer

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Glycemic indexWhich food will get into your

blood more quickly?applerice cakescorn flakesbagelpeanut M&M

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Glycemic indexRanking of carbohydrates based on their

immediate effect on blood glucose (blood sugar) levels

Carbohydrate foods that breakdown quickly during digestion have the highest glycemic indices. Their blood sugar response is fast & high.

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Glycemic indexWhich food will get into your

blood more quickly?apple 36rice cakes 82corn flakes 84bagel 72peanut M&M 33

Let’s build some

Carbohydrates!