Carbohydrates - twenty points to keep in mind.

1. among the most common organic material on Earth

2. used by organisms as sources of energy, as building materials, and as cell surface markers for cell-to-cell identification and communication

3. composed of carbon, hydrogen and oxygen in a 1:2:1 ratio

4. emperical formula:

where n represents the number of carbon atoms

5. the simplest carbohydrates are monosaccharides which contain a single chain of carbon atoms which hydroxyl groups are attatched, additionally the two simplest forms of monosaccharides are dihydroxyacetone and glyceraldehyde.

6. monosaccharides can be distinguished by the carbonyl group they possess, whether it be aldehyde of ketone, as well as the number of atoms in their carbon backbone

7. sugar with three carbons is called a triose, four carbons - tetrose, five carbons - pentose and six carbons - hexose

8. when two monosaccharides come together, it is called a disaccharide

9. when a few of the disaccharides form a covalent bond, it is called oligosaccharides

10. polymers consisting of chains of monosaccharide of disaccharide units are called polysaccharides

11. due to the tetrahedral nature of carbon bonds, and depending on the sugar, pyranose sugars form a 'chair' or 'boat' configuration

12. glycosidic bonds forms when the anomeric hydroxyl and a hydroxly of another sugar or some other compound that can join together which results in the splitting water and ultimately forming the glycosidic bond

13. plants store glucose as amylose of amylopectin, glucose polymers collectively called 'starch'

14. glucose storage in polymeric form minimizes osmotic effects

15. amylose if a glucose polymer withlinkages and adopts a helical conformation

16. the 'twin sister' named amylopectin is uglier, with a glucose polymer mainly  linkages, but it also has branches formed by linkages

17. amylopectin has a friend named glycogen with a similar structure with more  branches where the highly branched structure permits rapid release of glucose from glycogen stores

18. cellulose is a major component of plant cell walls for strength and rigidity, and it consists of long linear chains of glucose with  linkages

19. lectins are glycoproteins that recognize and bind to specific oligosaccharides

20. selectins are integral proteins of the plasma membrane with lectin-like domains that protrude on the outer surface of mammalian cells