20 Facts on Carbohydrat

1. Carbohydrate is one of the four macro-molecules .
2. The main function of carbohydrates is to store energy. They are the main energy source in living organisms.
3. Carbohydrates contain carbon, oxygen and hydrates only.
4. Monosaccharide can be divided into Aldoses and ketoses. Aldoses are the sugars that contain an aldehyde group at the end such as glucose. Differently, ketoses have a ketone group (most likely at C2) , one of the examples of ketoses is Fructose. 
5. Sugars are usually seen in pentatoses ( 5 carbons ) or hexoses (6 carbons ). In order to become stable, they generally would form a ring at where the carbonyl group is at. 
6. Fructose and glucose are both hexoses, even though fructose forms a ring of five carbons with one extra carbon attaches on the C5.
7. Sugars are not plain 2D diagrams but in real life it can be presented into two ways -- "chair" and "boat".However chair form is more stable.
8. Glycosidic bonds are formed when two sugars combine though a process of condensation (dehydration synthesis) . In which the water is produced in order to link two carbohydrates together. 
9. Opposite to condensation is the synthesis of hydrolysis. The process of separate two sugars by adding in the water.
10. Disaccharides means the molecule combined from two monosaccharides. Examples of disaccharides are : maltose,  a starch formed by two glucose (C1-4). Sucrose, commonly known as table sugar in which is formed by glucose and fructose. Lactose, it is found in the milk and formed from galactose with glucose.
11. The shape of α linkage looks like two molecules are "holding hands" and "pointing". Examples: Maltose, Sucrose.
12. The shape of β linkage is looks more similar as a straight line rather than α linkage. Example: Lactose.
13. Carbohydrate polymers ( such as starch, glycogen and cellulose ) are formed from many monosaccharides connected together with glycosidic linkages. 
14. Amylose is a glucose polymer with α(1-4) linkages. It normally presents in a single helix shape.
15. Amylopection is a glucose polymer with mainly α(1-4) linkage, but few of α(1-6) linkages in which is able to produce multiple chains. 
16. The polymer of energy storage in animals is called glycogen, in which is a glucose polymer with α(1-4) linkages and α(1-6) linkages. However, it contains more α(1-6) linkages than amylopectin so it is able to form more branches than amylopectin.
17. In order for the plant cells to keep its shape, the cell walls of plant cells contains cellulose. Cellulose has long chains of glucose with β(1-4) linkages in which stabilizes its shape. 
18. Humans are unable to digest cellulose in the plants ( such as grass or vegetables) due to the lack of the appreciate enzyme to breakdown the β linkages. Unlike humans, animals such as sheep or cow has the symbolic enzymes in the intestinal tract that allows them to digest the plants.
19. Oligosaccharides means few monosaccharides are joined together either in linear or branched chains. They covalently attached to proteins or to membrane lipids.
20. Selectins are integral proteins of the plasma membrane with lectin-like domain that protrude on the outer surface of mammalian cells.