Carbohydrates

Organic Molecules Giant molecules are called Macromolecules Most macromolecules are Polymers Polymer = large molecules consisting of many identical or similar subunits strung together Subunits of a polymer are Monomers

Dehydration Synthesis Monomers are linked together by Dehydration Synthesis The net effect of this process is the removal of a water molecule for each monomer in the chain This type of reaction is called a Dehydration Synthesis

Joining Two Monomers Two monomers join when one monomer loses an -OH and the other loses a H+ Energy is required This process occurs only with the help of enzymes

Disassembling Polymers Polymers are disassembled to monomers by Hydrolysis Bonds between monomers are broken down by the addition of water H+ from water attaches to one monomer and the -OH attaches to the other This is the reverse of Condensation Synthesis Ex. Digestion

4 Major Classes of Organic Compounds 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids

Carbohydrates Includes all sugars and their polymers Simplest form = Monosaccharide (simple sugars) Double Sugar = Disaccharide (made up of 2 monosaccharides) joined by a dehydration synthesis reaction Polymers of many sugars = Polysaccharide

Disaccharide Polysaccharide

Monosaccharides General Formula is CH2O The number of these units ranges 3-7 carbons long Most common Monosaccharide is GLUCOSE C6H12O6 which is a major cellular fuel.

Monosaccharide Functional Groups Hydroxyl attached to each Carbon except one One carbon is double bonded to oxygen to form a carbonyl group Depending on the location of the carbonyl, a sugar is either: aldehyde ketone alcohol

Glucose is an ALDOSE (hexose) Fructose is a KETOSE (hexose)

Another source of diversity in simple sugars is the spatial arrangement of their parts around symmetric carbon atoms In aqueous solutions, glucose and other sugars form rings. Glucose is broken down to yield energy in cellular respiration. Monosaccharides are the building blocks for synthesis of other smaller organic molecules.

Disaccharides Double sugars that consist of 2 monosaccharides joined by dehydration synthesis and a covalent bond between monosaccharides Examples: Maltose = 2 Glucose (beer, seed germination) Lactose = Glucose + Galactose (milk) Sucrose = Glucose + Fructose (plant sugar)

Oligosaccahrides Short chains made of 2 or more monomers When 3 or more monomers are present they are sometimes attached as side chains to proteins and aid in membrane function

Polysaccharides Made up of a few 100 to a few 1,000 Monosaccharides Can be straight or branched chains

Storage Polysaccharides Used as a storage material. Ex. Starch - consists of only glucose and can be hydrolyzed when needed to produce sugar Simplest form of starch = Amylose - unbranched Plants store starch to save up sugars “carb. Banking” for long term energy needs

Animal Energy Needs Most animals have enzymes to hydrolyze plant starch to make glucose available as a nutrient for cells Animals produce/store Glycogen, a highly branched polymer of glucose, as their energy storage form. Humans store glycogen in the muscles & liver cells.

Animal Energy Needs Humans hydrolyze the glycogen to release glucose when sugar demand increases The “Bank” depletes within a day but gets replenished by eating more food.

Structural Polysaccharides Used for support ex. Cellulose - found in Cell Wall of plant cells. It’s one of the most abundant organic compounds on Earth Cellulose is tough & insoluble

Cellulose Like starch, cellulose is a polymer of glucose, but the configuration of the ring form of glucose differs. In cellulose, the glucose monomers are in the Beta configuration. This means that the hydroxyl is locked above the plane of the ring.

Starch In starch the glucose monomers are in the alpha configuration. This means that the hydroxyl is locked below the plane of the ring. This variation in geometry of starch and cellulose allows each to have different properties.

Enzymes Enzymes that digest starch by hydrolyzing the alpha bonds are unable to hydrolyze the beta linkages of cellulose. Humans don’t have the enzymes that can break the beta link. Cellulose then becomes undigestable dietary fiber (roughage)

Put in your NOTECARDS: 1. Explanation of Dehydration Synthesis 2. Explanation of Hydrolysis 3. The General Formula for a Carbohydrate 4. Explain the difference between a Monosaccharide and a Polysaccharide 1 NOTECARD