Organic Macromolecules: Carbohydrates Biochemistry Organic Macromolecules: Carbohydrates

Organic macromolecules: carbohydrates Carbohydrates are organic compounds that contain carbon, hydrogen, and oxygen in a ratio of CnH2mOm (Hydrogen:Oxygen ratio = 2:1) There are three categories of carbohydrates: monosaccharide, disaccharide, and polysaccharide.

Organic macromolecules: carbohydrates Monosaccharide – a simple sugar Disaccharide – two monosaccharides joined together through a dehydration synthesis Polysaccharide – a sugar macromolecule composed of many monosaccharides (polysaccharides are carbohydrates)

Organic macromolecules: carbohydrates The most common monosaccharide is glucose The chemical formula for glucose is C6H12O6 Glucose can be found as an aldose or ketose based on the carbon atom the carbonyl group is added to.

Organic macromolecules: carbohydrates Glucose (aldose) Fructose (ketose)

Organic macromolecules: Carbohydrates Glucose can exist in two forms α glucose and β glucose

Organic macromolecules: carbohydrates Disaccharides and Polysaccharides are formed when monosaccharides are joined together through a dehydration synthesis A glycosidic bond (linkage) is formed when two monosaccharides are joined together. Glycosidic bond (linkage) – the connection in a disaccharide or polysaccharide chain formed by the removal of water.

Organic macromolecules: carbohydrates

Organic macromolecules: carbohydrates When two monosaccharides are joined together it is called a disaccharide Different disaccharides are formed based on two variables: The carbon atoms that are being joined between the monosaccharides The types of monosaccharides being joined

Organic macromolecules: carbohydrates

Organic macromolecules: carbohydrates Polysaccharides can be used for storage of energy and structure. Starch is a polysaccharide in plants made entirely of α glucose monomers. One type of starch is amylose and it is comprised of 1-4 linkages (number 1 carbon of one glucose molecule bonds to the number 4 carbon of the next glucose molecule) The angle of this bond makes the polysaccharide helical

Organic macromolecules: carbohydrates Another type of starch is amylopectin and it is comprised of mostly 1-4 linkages but it branches so it has 1-6 linkages at the branch *amylose and amylopectin are sugars made by plants. Amylase is an enzyme found in human saliva and is made by the pancreas to break down these sugars in our food*

Organic macromolecules: carbohydrates

Organic macromolecules: carbohydrates Glycogen is an energy storage molecule in animals made up of glucose monomers Glycogen is similar to amylopectin, except that it contains numerous branches. Most vertebrate animals store glycogen primarily in the liver and muscles.

Organic macromolecules: carbohydrates

Organic macromolecules: carbohydrates Cellulose is another polysaccharide found in plants Like starch, cellulose is made up glucose monomers but they are all in the β conformation so that every other glucose molecule in the polysaccharide is flipped. This allows strands of cellulose to hydrogen bond with eachother and become very strong The strength of cellulose gives the structure to plants and plant cells

Organic macromolecules: carbohydrates

Organic macromolecules: carbohydrates Very few organisms have the enzymes to break down cellulose Enzymes designed to break down starch do not break down cellulose Cows have the enzymes needed to break down cellulose as do some microbes Humans cannot break down cellulose but it helps in digestion and is still a necessary part of a healthy diet