1. AP Biology Discussion Notes
Monday 9/28

2. Goals for Today:
Be able to describe and compare the building, breaking, components, and functions of Carbohydrates.

3. 9/28 Question of the Day:
Who (What) am I?

4. Organic Chemistry - the chemistry of _________
All organic compounds contain: ____
is the reverse true? give an example

5. Organic Chemistry
- the chemistry of Life
All organic compounds contain carbon, but not all carbon-containing compounds are organic!

6. The Molecules of Life
All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids
Macromolecules are large molecules composed of thousands of covalently connected atoms
Molecular structure and function are inseparable

7. Macromolecules are polymers, built from monomers
A polymer is a long molecule consisting of many similar building blocks
These small building-block molecules are called monomers
Three of the four classes of life’s organic molecules are polymers
Carbohydrates
Proteins
Nucleic acids

8. The Synthesis and Breakdown of Polymers
A dehydration synthesis occurs when two monomers bond together through the loss of a water molecule
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction

9. (a) Dehydration reaction: synthesizing a polymer
Figure 5.2a
(a) Dehydration reaction: synthesizing a polymer 1 2 3
Short polymer
Unlinked monomer
Dehydration removes a water molecule, forming a new bond.
Figure 5.2 The synthesis and breakdown of polymers. 1 2 3 4
Longer polymer

10. (b) Hydrolysis: breaking down a polymer
Figure 5.2b
(b) Hydrolysis: breaking down a polymer 1 2 3 4
Hydrolysis adds a water molecule, breaking a bond.
Figure 5.2 The synthesis and breakdown of polymers. 1 2 3

11. The Diversity of Polymers
Each cell has thousands of different macromolecules
Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species
An immense variety of polymers can be built from a small set of monomers
*Think alphabet & words HO

12. Characteristics of Carbohydrates (composition, uses, examples)
RATIO?
CHO H:O in a 2:1 ratio – help recognize carbs
Starches & Sugars

13. Carbohydrate Foods

14. Sugars
Monosaccharides have molecular formulas that are usually multiples of CH2O
Glucose (C6H12O6) is the most common monosaccharide
Monosaccharides are classified by
The location of the carbonyl group (as aldose or ketose)
The number of carbons in the carbon skeleton

15. (a) Linear and ring forms
Figure 5.4 1 6 6 2 5 5 3 4 1 4 1 4 2 2 5 3 3 6
(a) Linear and ring forms
Figure 5.4 Linear and ring forms of glucose. 6 5 4 1 3 2
(b) Abbreviated ring structure

16. Glucose—a monosaccharide

17. Forming a Disaccharide—Dehydration Synthesis
Glycosidic Bond

18. Another look...

19. A disaccharide is formed when a dehydration reaction joins two monosaccharides
This covalent bond is called a glycosidic linkage/bond
What are the linkages/bonds in Proteins called?

20. Polysaccharides
Polysaccharides, the polymers of sugars, have storage and structural roles
The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages
(Determined by arrangement/organization!)
Determined by arrangement/organization

21. Storage Polysaccharides
Starch, a storage polysaccharide of plants, consists entirely of glucose monomers
Plants store surplus starch as granules within chloroplasts and other plastids
The simplest form of starch is amylose
Glycogen is a storage polysaccharide in animals
Humans and other vertebrates store glycogen mainly in liver and muscle cells

22. (a) Starch: a plant polysaccharide
Figure 5.6
Chloroplast
Starch granules
Amylopectin
Amylose
(a) Starch: a plant polysaccharide
1 m
Mitochondria
Glycogen granules
Figure 5.6 Storage polysaccharides of plants and animals.
Glycogen
(b) Glycogen: an animal polysaccharide
0.5 m

23. Structural Polysaccharides
The polysaccharide cellulose is a major component of the tough wall of plant cells
Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ
The difference is based on two ring forms for glucose: alpha () and beta ()

24. Cellulose microfibrils in a plant cell wall
Figure 5.8
Cellulose microfibrils in a plant cell wall
Cell wall
Microfibril
10 m
0.5 m
Figure 5.8 The arrangement of cellulose in plant cell walls.
Cellulose molecules
 Glucose monomer

25. Cellulose by another name….
Enzymes that digest starch by hydrolyzing  linkages can’t hydrolyze  linkages in cellulose
Cellulose in human food passes through the digestive tract as insoluble fiber
Some microbes use enzymes to digest cellulose
Many herbivores, from cows to termites, have symbiotic relationships with these microbes

26. Structural Polysaccharides
Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods
Chitin also provides structural support for the cell walls of many fungi

27. Some Polysaccharides (carbohydrate polymers)
Add Chitin

28. Let’s Build Some

29. Work order for today Carbohydrate building
Finish Protein reading from last week.
Write down questions so we can talk about them tomorrow.
DUE WEDNESDAY