Carbohydrates IB Biology
Molecular Models Kits • In your groups, you have a kit. We will be making models with these over the next several class periods. • To begin, in your warmup book, make a new page and title it, “Molecular Models Activity.” • You will number each one, draw it, and get an initial. • #1- Water, H2O • #2- Methane, CH4 • Build these models now and get them initialed.
Review: Polymer Principles •Four classes of macromolecules: –Carbohydrates –Lipids –Proteins –Nucleic Acids •Polymers are made up of smaller parts called monomers. •Polymers are formed through condensation reactions. •Polymers are broken apart through a hydrolysis reaction.
General Information about Carbohydrates •Carbohydrates are composed of C, H, and O CH2O (CH2O)x C6H12O6 –“Carbo”-contains carbon –“Hydrate”- Compound containing chemically combined water. •Often end in “-ose”
General info about carbohydrates •Functions: –Immediate energy source for cells –Energy storage for later use –Raw material for building other molecules –Important role in cell membrane recognition About 17 KJ of energy per dry gram. About the same as protein, but ½ that of lipids
Monosaccharides-one sugar unit (monomer)– are the simplest carbohydrates •Backbone of 3-7 carbon atoms •Form ring structures in cells •Characterized by sweet taste •Have several polar -OH groups, so they are soluble in water. (The many –OH groups can hydrogen bond with water molecules)
Label the slight positive and slight negatives on the highlighted O’s and H’s. HINT: Remember polarity and unequal pull of electrons
Using the molecular model kits, build a model of glucose Notice orientation of hydroxyl (OH) groups Initial when complete
Glucose • C6H12O6 • A product of photosynthesis • Needed for ATP synthesis during cellular respiration
Draw a water molecule hydrogen bonding off of EACH highlighted H and EACH highlighted O. –Be sure you correctly orient the H’s and O’s of the water molecule –Show the hydrogen bond with a dotted line (you should end up drawing 10 H2O’s)
Some example monosaccharides • Glucose • Ribose • Deoxyribose • Fructose
Deoxyriboseand ribose are the building blocks for nucleic acids. Found in RNA** Found in DNA
Fructose • Found in fruits • Used by plants to attract animals to the fruit for seed dispersal.
Isomers • Glucose and fructose have the same chemical formula C6H12O6 but different structural arrangement of the atoms (called isomers)
The monosaccharides glucose, fructose, and galactose are isomers. • They contain the same atoms but in different arrangements All are C6H12O6
Disaccharides Di = 2 Saccharide = sugar
Disaccharides are formed in Condensation Reactions http://kisdwebs.katyisd.org/campuses/MRHS/teacherweb/hallk/Teacher%20Documents/AP%20Biology%20Materials/Chemistry%20of%20Life/Condensation%20and%20Hydrolysis%20Reactions/conde_shell.html
Maltose (two glucose units) provides energy for germinating seeds. H2O Formula: C12H22O11 (glucose + glucose – H2O)
Maltose – between which carbon #’s are the glucoses connected? H2O
Sucrose(glucose + fructose) is a transport form of sugar used by plants and harvested by humans for food.
Splenda: A modified disaccharide • Splenda is just a modified form of sucrose • Notice the chloride ions that replace the hydroxyl groups
On your lab drawings paper, draw 2 glucoses next to each other. -On your first glucose, highlight the hydroxyl(-OH) on carbon 1. -On your second glucose, highlight the hydroxyl(-OH) on carbon4.
Using the molecular model kits: BUILD MALTOSE Notice orientation of hydroxyl (-OH) groups.
When finished with maltose • Combine each group’s maltose’s to make one long chain. Draw this. This is a model of starch.
Complex Carbohydrates:The Polysaccharides •Polymers of hundreds or thousands of sugar monomers –costs little energy to build –easily reversible = release energy when digested
Storage Polysaccharides • What does it mean to store something?
Storage Polysaccharides –Starch (polymer of glucose) •Found in PLANTS •Formed in roots and seeds as a form of glucose storage –Glycogen (polymer of glucose) •Found in ANIMALS •Formed in the liver and muscles as a form of glucose storage
Structural Polysaccharides •Cellulose (polymer of glucose) –Most abundant organic compound on Earth –Found in the cell walls of plants –Indigestible for most animals due to orientation of bonds between glucoses
Structural Polysaccharides •Chitin (polymer of modified glucose units) –Found in the outer coverings of insects, crabs, and spiders –Found in the cell walls of many fungi
Starch vs. Cellulose • Cellulose • Polymer of b-glucose • Linear, does not branch • Has b 1-4 linkages • Most animals lack the enzyme to break the b 1-4 linkages (so we can’t digest it). • Starch: • Polymer of a-glucose • Highly branched • Has a 1-4 linkages • Used for storage in plants.
enzyme enzyme Digesting starch vs. cellulose starcheasy todigest cellulosehard todigest
Cow can digestcellulose well; no need to eat other sugars Gorilla can’t digestcellulose well; must add another sugar source, like fruit to diet
Helpful bacteria • How can herbivores digest cellulose so well? • BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals Tell me aboutthe rabbits,again, George! I eatWHAT! Ruminants
Summary of Carbohydrates • Monosaccharides: Glucose, Fructose, Galactose, Ribose • Disaccharides: Lactose, Maltose, Sucrose • Polysaccharides: Starch, Cellulose, Glycogen, Chitin • Alpha (starch) & Beta (cellulose) linkages • Chitin: exoskeleton, suture, and fungi (cell walls)