1. Annie Stetz & Peter Collins
5.2 Carbohydrates
Annie Stetz & Peter Collins

2. Carbohydrate serve as fuel and building material:
Carbohydrates: includes both sugars and polymers of sugars
Simplest are monosaccharides (aka simple sugars)
Disaccharides: double sugars
2 monosaccharides joined by a covalent bond
Carbohydrates also include macromolecules
Polysaccharides
Polymers composed manly of sugar building blocks

3. Sugar
Monosaccharides usually have molecular formulas that are some multiple of CH2O
Glucose is the most common and is a keystone in the chemistry of life
Diversity of simple sugars can be seen in the spatial arrangements of their parts around asymmetric carbon
Monosaccharides are major nutrients for cells
The carbon skeletons of single sugars serve as raw materials for the synthesis of other small organic molecules
Disaccharides consist of 2 monosaccharides joined by a glyosidic linkage ( a covalent bond between 2 monosaccharides by a dehydration reaction)
The most prevalent disaccharide is sucrose

4. Polysaccharides Polysaccharides are macromolecules
Some serve as storage material others serve as building material for structures that protect cells or whole organisms

5. Storage Polysaccharides
Both plants and animals store sugars in the form of storage polysaccharides
Plants store starch, a polymer of glucose monomers.
Because glucose is a major cellular fuel, starch represents stored energy
Most animals, includes humans, have enzymes that hydrate plant starch
Making glucose available to cells
Most glucose monomers are joined together by 1-4 carbon linkages
Animals store a polysaccharide called glycogen
a polymer of glucose that is like a amylopectin but more extensively breached.

6. Structural Polysaccharides
A polysacciraide called cellulose is a major component in the walls that enclose plant cell.
Cellulose is a polymer of glucose, but the glycosidic linkages in these two polymers differ
All glucose monomer are in an alpha configuration
The differing glycosidic linkages in starch give it a three dimensional shapes
Starch: helical
Cellulose: straight
In plant cell walls parallel cellulose molecules are grouped into microfibrils.
Strong building materials for plants and an important substance for humans even though humans can not digest it
Some prokaryotes, cows, and termites can digest cellulose

8. Structural Polysaccharides
Chitin is another important structural polysaccharide
The carbohydrate used by arthropods to build there exoskeletons
Also found in many fungi
Uses chitin to build their cell walls
Similar to cellulose
Except chitin has a nitrogen-containing appendages