1. Chapter 5.2
AP Biology
Dr. Solis

2. Carbohydrates serve as fuel and building material
Polymers of Sugars
Disaccharides (double sugars)
Polysaccharides
(macromolecules)
Sugars
Monosaccharides (simple sugars)

3. Carbohydrates
Monosaccharides – simple sugars

4. Carbohydrates
I feel dehydrated
Disaccharides – double sugars
Me too.

5. Carbohydrates
Polysaccharides – polymers composed of many sugar building blocks
Sugar

6. Remember: Sugars are Carbs!
Most names for sugars end in ose
Glucose, fructose,
Monosaccharides generally have molecular formulas that are some multiple of the unit CH2O

7. Sugars? Nutritious? Glucose is a monosaccharide
Is a major nutrient to the cell
Important for: Cellular respiration
Cellular respiration: Cells extract energy in a series of reactions made possible by glucose
The carbon skeleton of glucose lays a foundation for other the synthesis of other molecules (amino acids, fatty acids)

8. Disaccharide
Disaccharide consists of two monosaccharides joined by glycosidic linkage.
Glycosidic linkage: simply – the dehydration reaction formed by the molecules forming a covalent bond.
Lactose is a disaccharide in milk.
Maltose is a sugar in beer.
Sucrose is table sugar.

9. Polysaccharides
Polysaccharides – macromolecules (a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
Serve as structures and building material for cells and organisms

10. Polysaccharides Some are stored for later use
These are things like ‘starch’ in plants
Stockpiling of surplus glucose
Sugar can be withdrawn later through hydrolysis
Potatoes, grains, corn, rice – starch in the human diet

11. 5.2 – Part 2 Important Polysaccharides
Review: Plants store sugar in the form of starch.
Starch is a polysaccharide
Human diets are made up mostly of starch.

12. Important Polysaccharides
Glycogen – A polymer of glucose
Animals (including humans and other vertebrates) store glycogen in liver and muscle cells
Hydrolysis in these cells release glucose when the demand for sugar increases
Glycogen is stored; but not for long
In humans, glycogen is depleted in about a day unless it is replenished.
Gives the animal much needed fuel when none other is available.
How would this be a concern for people on a low-carb diet?

13. Glycogen has 30,000 glucose units

14. Structural Polysaccharides
Polysaccharides are also important because:
Organisms can build strong materials from them
Cellulose is a polysaccharide

15. Structural polysaccharides
Cellulose is important because:
A major component of the cell walls that enclose plant cells
Globally, plants produce almost 100 billion tons of cellulose per year.
It is the most abundant organic compound on Earth

16. Cellulose Structure
Cellulose is also a polymer of glucose (like starch)
But it differs in its structure
In starch - all monomers are in the same orientation
But in cellulose, every other beta glucose monomer is upside down

17. Cellulose
In plant cell walls, cellulose molecules held together in a parallel way are grouped into units called microfibrils
Cable like structures – that are very strong

18. Cellulose
Cellulose is the major component of paper and the only component of cotton

19. Cellulose
Normal enzymes are unable to hydrolyze the linkages in cellulose
Most organisms cannot digest cellulose
Humans cannot digest cellulose – so it passes through our body without being broken down.
What animals can you name that can digest cellulose?