Summary for the 5.2

Carbohydrates provide fuel and building material

Sugars
A carboohydrate is an organic compound made up of sugar molecules. It contains carbond, hydrogen and oxygen in the ratio of C1:H2:O1.(CH2O)
Monnosaccharides are simple sugar contain just one sugar unit (Glucose). These type of sweet sugars are well known to us like honey. Glucose exists in both straight-chain and ring-shaped forms.
Sugars molecules are the main supporter of cellular work. How it work is that, cells break down their stored glucose molecules and extract energy from it. But if there are too much glucose or not used immediatetly, it became fat molecules.
Using the dehydration reaction, cells construct a disaccharide or "double sugar" from two monosaccharides. The sucrose, the most common disaccharide molecule, it consists of a glucose molecule linked to a fractose molecule.

Polysaccharides
Long polymer chains made up of simple sugar monomers are called polysaccharides, or complex carbohydrates. For example, starch is a polysaccharide found in plant cells that consists entirely of glucose monomers. It's chain branch and coil up like the loops of a telephone cord. It's like stockpiles. Everything needs sugar to work, humans digest sugars within thier digestive systems.
Animal cells do not contain starch. Instead, animals such as turkeys (and humans) store excess sugar in the form of a polysaccharide called glycogen. It's like starch, is a chain of many glucose monomers. In humans, it's stored in granules in liver and muscle cells. When body needs energy, it break downs and release glucose.
Cellulose, served as building materials. They protect cells and stiffen the plant, preventing it from flopping over. Like starch and glycogen, cellulose is also made up of glucose monomers.
Most living thins can't digest cellulose. So, cellulose from plants foods, commonly referred to as"fiber", passes unchanged through your digestive system. It helps your digestive system healthy but it's not a nutrient.
All most all carbohydrates are hydrophilic. It's because there are many hydroxyl groups in thier sugar units. So monosaccharides and disaccharides solute for water. But cellulose and some form of starch aren't solute of water.

1. Monosaccharide is is a simple sugar that contain only one sugar unit but disacchride have double sugar from two monosaccharide.

2, All these three are consist of glucose molecules. But starch is found in plant cells and glycogen is chain of glucose monomers, more highly branched then starch, and stored in our liver and muscle cells. Cellulose is consist of glucose molecules but what it does is different and it's chain is linked to hydrogen bonds.