Chapter 5- The Structure and Function of Macromolecules Carbohydrates AP BIOLOGY

Macromolecules Carbohydrates Proteins Lipids Nucleic Acids

Carbohydrates

Polymer Vs. Monomer Polymer: A large molecule made up of identical or similar building blocks Ex. Polysaccaride Starches Monomer: the building block that is used to make polymers Glucose

Carbohydrates Carbohydrates are composed of C, H, O Most names for sugars end in –ose CH2O (Empirical Formula) (CH2O) C6H12O6 Contains a Carbonyl (C=O) & many Hydroxyl (OH) Function: Energy & Storage ex: sugars, starches, cellulose, chitin (CH2O)x C6H12O6 carb = carbon hydr = hydrogen ate = oxygen compound

Monosaccharides Simple 1 monomer sugars Ex’s: Glucose Frucotose Galactose sugar

Biological function of monosaccharides ENERGY!!!! Key parts of other molecules (e.g. nucleic acids, ATP) Monomers for Disaccharides & Polysaccharides. They form polymers in dehydration reactions.

Classifying Monosaccharides Monosaccharides are uniquely identified based on: The location of the carbonyl carbon in the straight chain form The number of carbons present The spatial arrangement of carbons

Sugar structure 5C & 6C sugars form rings in solution Where do you find solutions in biology? In cells!

Identifying monosaccharides alpha-glucose beta-glucose The arrangement of the –OH group on the #1 carbon does not matter when naming sugars. The location of the other groups on the 2,3,4, and 5 carbons does matter.

C C O C C C C Carbons are numbered energy stored in C-C bonds 5' 4' 1' 6' C O 5' C C 4' 1' energy stored in C-C bonds C C 3' 2'

Carbon Skeleton 6 5 3 3-7 Carbons long Classified by number of carbons 6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde) Glyceraldehyde H OH O C OH H HO CH2OH O Glucose H OH HO O Ribose CH2OH 6 5 3

Functional groups determine function Aldehyde Carbonyl at end Ketone Carbonyl in middle

Forming Disaccharides glucose+ glucose= Disaccharide monomer monomer Polymer

Disaccharides Sucrose Lactose Maltose 2 monomers Held by Monosaccharides Sucrose Glucose + Fructose Lactose Galactose Maltose 2 monomers Held by glycosidic bonds Ex’s Sucrose Lactose Maltose

Building sugars Dehydration synthesis sucrose (table sugar) glucose monosaccharides disaccharide H2O sucrose (table sugar) | glucose | fructose sucrose = table sugar

Building sugars glycosidic linkage glucose glucose maltose monosaccharides disaccharide H2O maltose glycosidic linkage | glucose | glucose | maltose

Lactose

Glucose and Fructose Glucose

Polysaccharides Polymers of sugars costs little energy to build Function: energy storage starch (plants) glycogen (animals) in liver & muscles structure cellulose (plants) chitin (arthropods & fungi) Polysaccharides are polymers of hundreds to thousands of monosaccharides

Polysaccharides Polymers of sugars joined by glycosidic linkages. Serve two main functions Storage- glycosidic linkages are hydrolyzed to obtain monosaccharides as energy is needed. Structural- make up the materials that are used to protect the organism.

Glycosidic Bonds Chemical linkage between the monosaccharide units of disaccharides, and polysaccharides, which is formed by the removal of a molecule of water Condensation reaction Bond forms between the carbon-1 on one sugar and the carbon-4 on the other.

Α & β Glycosidic Bonds in cellulose in starch An α-glycosidic bond- formed when the –OH group on carbon-1 is below the plane of the glucose ring A β-glycosidic bond is formed when it is above the plane. Ex. Cellulose- formed of glucose molecules linked by 1-4 β-glycosidic bonds (Above plane) Ex. Starch- composed of 1-4 α-glycosidic bonds (Below plane ) in cellulose in starch

Polysaccharides- 100’s to 1000’s of monosaccharides Storage Polysaccharides Structural Polysaccharides Starch Plants Cellulose Glycogen Animals Chitin Animals-Insects Fungi

Structural Polysaccharides Key in forming the structure of an organism. Most common structural polysaccharide is cellulose. Makes up cell walls in plants Used to make paper Chitin Polymer of glucose Forms via 1-4 glycosidic linkage.

Cellulose Most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulose most carnivores have not cellulose = undigestible roughage Cross-linking between polysaccharide chains: = rigid & hard to digest The digestion of cellulose governs the life strategy of herbivores. Either you do it really well and you’re a cow or an elephant (spend a long time digesting a lot of food with a little help from some microbes & have to walk around slowly for a long time carrying a lot of food in your stomach) Or you do it inefficiently and have to supplement your diet with simple sugars, like fruit and nectar, and you’re a gorilla. But it tastes like hay! Who can live on this stuff?!

Cow Gorilla can digest cellulose well; no need to eat other sugars can’t digest cellulose well; must add another sugar source, like fruit to diet The digestion of cellulose governs the life strategy of herbivores. Either you do it really well and you’re a cow or an elephant (spend a long time digesting a lot of food with a little help from some microbes & have to walk around slowly for a long time carrying a lot of food in your stomach) Or you do it inefficiently and have to supplement your diet with simple sugars, like fruit and nectar, and you’re a gorilla. APBioTOPICS/20Biochemistry/MoviesAP/Macromolecule-Lifewire.swf

Helpful bacteria How can herbivores digest cellulose so well? BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals Rumen-Upper part of stomach

Digesting starch vs. cellulose enzyme starch easy to digest cellulose hard to digest Starch = all the glycosidic linkage are on same side = molecule lies flat Cellulose = cross linking between OH (H bonds) = rigid structure enzyme

Plant Storage Polysaccharides Starch is the main storage polysaccharide- Found in two forms. Amylose- main storage polysaccharide found in plants. 1-4 glycosidic linkage found in glucose. Amylopectin- also in plants. Like starch with branching. Branch occurs with a 1-6 glycosidic link.

Storage Polysaccharide in Animals Glycogen is the main storage polysaccharide in animals. It is even more highly branched than amylopectin. Stored primarily in muscle and liver cells and is used when glucose stores are low.

Polysaccharide diversity Molecular structure determines function in starch in cellulose isomers of glucose structure determines function…

Linear vs. branched polysaccharides slow release starch (plant) energy storage Can you see the difference between starch & glycogen? Which is easier to digest? Glycogen = many branches = many ends Enzyme can digest at multiple ends. Animals use glycogen for energy storage == want rapid release. Form follows function. APBio/TOPICS/Biochemistry/MoviesAP/05_07Polysaccharides_A.swf glycogen (animal) fast release

Starch Unbranched Glycogen Branched Chloroplast Starch Mitochondria Fig. 5-6 Chloroplast Starch Mitochondria Glycogen granules 0.5 µm 1 µm Amylose Glycogen Amylopectin Starch Unbranched Glycogen Branched

Difference between starch and cellulose Starch production involves 1-4 glycosidic linkage of a-glucose monomers. Helical shape Cellulose production involves 1-4 glycosidic linkage of b-glucose monomers Never branched , straight a- Glycogen b- Cellulose Does this matter?

(a)  and  glucose ring structures Fig. 5-7a  Glucose  Glucose (a)  and  glucose ring structures

(b) Starch: 1–4 linkage of  glucose monomers Fig. 5-7bc (b) Starch: 1–4 linkage of  glucose monomers (c) Cellulose: 1–4 linkage of  glucose monomers

Chitin Chitin is the structural polysaccharide in arthropods Ex. insects, spiders, crustaceans, and fungi. Similar to cellulose, but it has a slightly different monomer that is a derivative of glucose

(a) The structure of the chitin monomer. (b) (c) Chitin forms the Fig. 5-10 (a) The structure of the chitin monomer. (b) Chitin forms the exoskeleton of arthropods. (c) Chitin is used to make a strong and flexible surgical thread.

YES, It matters! Cellulose has a much different structure than starch. In storage polysaccharides, the polymer hydrogen bonds mainly with itself to form helices (spirals) Ex. Glycogen In structural polysaccharides, the polymer hydrogen bonds with other polymer strands to form a strands that form thread like structures Ex. Chitin & Cellulose

Starch vs. Cellulose Helix Sheet

IT REALLY MATTERS Animals lack the enzymes (cellular machinery) to break down cellulose. Only a few bacteria and fungi can break down cellulose.