Carbohydrates

Polymer Principles Polymers are made up of smaller parts called monomers. Four classes of macromolecules: Carbohydrates Lipids Proteins Nucleic Acids Polymers are formed through condensation reactions. Polymers are broken apart through a hydrolysis reaction.

General Information about Carbohydrates Often end in “-ose” “Carbo”-contains carbon “Hydrate”-hydrogen and oxygen are present in the same proportions as in water

What Are Carbohydrates? Carbohydrate composition Made of C, H, and O in the ratio of 1:2:1 Construction Simple or single sugars are monosaccharides Two linked monosaccharides are disaccharides Long chains of monosaccharides are polysaccharides

Monosaccharides One sugar unit – are the simplest carbohydrates They are characterized by sweet taste They have several polar -OH groups, so they dissolve in water

IB Example: RIBOSE Monosaccharides with a 5 carbon backbones Ribose (and deoxyribose) are the building blocks for nucleic acids.

Build ribose with the model kit Carbon – black Oxygen – red Nitrogen - blue Hydrogen - white Determine the molecular formula of ribose Stamp when complete

IB EXAMPLE: GLUCOSE Monosaccharide with a 6 carbon backbone One of the products of photosynthesis. In animals and fungi, glucose is the result of the breakdown of glycogen. In plants the breakdown substrate is starch. In animals, glucose is synthesized in the liver and kidneys Glucose is needed for ATP synthesis during cellular respiration

Build glucose with the model kit Carbon – black Oxygen – blue Red – nitrogen White – hydrogen Determine the molecular formula Stamp when complete Do not break apart!

EXAMPLE: FRUCTOSE Monosaccharide with a 6 carbon backbone Found in fruits and honey. It is classified as the sweetest of all the sugars.

Build fructose with the model kit Carbon – black Oxygen – blue Red – nitrogen White – hydrogen Determine the molecular formula Stamp when complete Do not break apart!

Glucose and fructose have the same chemical formula C6H12O6 but different structural arrangement of the atoms

Disaccharides – two sugar units bonded together

Disaccharides are formed in condensation reactions

Maltose (two glucose units) is present in germinating seeds.

Build maltose with the model kit Carbon – black Oxygen – blue Red – nitrogen White – hydrogen Use your previously made glucose and fructose Determine the molecular formula Stamp when complete Break apart!

Sucrose (glucose + fructose) is a transport form of sugar used by plants and harvested by humans for food.

Sucrose

Lactose (glucose and galactose) is present in milk

Figure 5.5x Glucose monomer and disaccharides Sucrose Maltose

Complex carbohydrates: the polysaccharides A polysaccharide is a straight or branched chain of hundreds or thousands of sugar monomers.

Storage polysaccharides Starch (polymer of glucose) PLANTS Formed in roots and seeds as a form of glucose storage Glycogen (polymer of glucose) ANIMALS Found in liver and muscles

FIGURE 3-8 Starch is an energy-storage polysaccharide made of glucose subunits (a) Starch globules inside individual potato cells. Most plants synthesize starch, which forms water-insoluble globules consisting of many starch molecules. (b) A small section of a single starch molecule, which occurs as branched chains of up to half a million glucose subunits. (c) The precise structure of the blue highlighted portion of the starch molecule in (b). Notice the linkage between the individual glucose subunits for comparison with cellulose (see Fig. 3-9).

FIGURE 3-8 (part 1) Starch is an energy-storage polysaccharide made of glucose subunits (a) Starch globules inside individual potato cells. Most plants synthesize starch, which forms water-insoluble globules consisting of many starch molecules. (b) A small section of a single starch molecule, which occurs as branched chains of up to half a million glucose subunits. (c) The precise structure of the blue highlighted portion of the starch molecule in (b). Notice the linkage between the individual glucose subunits for comparison with cellulose (see Fig. 3-9).

FIGURE 3-8 (part 2) Starch is an energy-storage polysaccharide made of glucose subunits (a) Starch globules inside individual potato cells. Most plants synthesize starch, which forms water-insoluble globules consisting of many starch molecules. (b) A small section of a single starch molecule, which occurs as branched chains of up to half a million glucose subunits. (c) The precise structure of the blue highlighted portion of the starch molecule in (b). Notice the linkage between the individual glucose subunits for comparison with cellulose (see Fig. 3-9).

Build starch with the model kit With a neighboring row, construct part of a starch molecule by joining four glucose molecule. Carbon – black Oxygen – blue Red – nitrogen White – hydrogen Stamp when complete Break apart!

Structural polysaccharides Cellulose (polymer of glucose) Found in the cell walls of plants Indigestible for most animals due to orientation of bonds between glucoses Chitin (polymer of modified glucose units) Found in the outer coverings of insects, crabs, and spiders Found in the cell walls of many fungi

FIGURE 3-9 Cellulose structure and function Cellulose can be incredibly tough. (a) Wood in this 3000-year-old bristlecone pine is primarily cellulose. (b) Cellulose forms the cell wall that surrounds each plant cell. (c) Plant cell walls often consist of cellulose fibers in layers that run at angles to each other and resist tearing in both directions. (d) Cellulose is composed of glucose subunits. Compare this structure with Fig. 3-8c and notice that every other glucose molecule in cellulose is "upside down."

FIGURE 3-10 Chitin: A unique polysaccharide Chitin has the same bonding configuration of glucose molecules as cellulose does. In chitin, however, the glucose subunits have a nitrogen-containing functional group (yellow) instead of a hydroxyl group. Tough, flexible chitin supports the otherwise soft bodies of arthropods (insects, spiders, and their relatives) and certain fungi, such as this mushroom.