1. CARBOHYDRATES
L3 Biology

2. Make the above structures (hydroxyl group on Carbon)
Perform Dehydration Synthesis!

3. FACTS ABOUT CARBOHYDRATES
Includes sugars, starches, cellulose, glycogen
Made up of carbon (C), hydrogen (H), and oxygen (O)
The ratio of hydrogen to oxygen is always 2:1 (like water)
Provide ENERGY!

4. Carb facts, cont. Simple sugars = monosaccharides and disaccharides
Complex sugars= polysaccharides
The chemical names of sugars end in -ose

5. Simple SUGARS Monosaccharides or disaccharides They taste sweet!
EXAMPLE: glucose
The chemical formula for glucose is C6 H12 O6
The structural formula for glucose is

6. GLUCOSE
C6H12O6

7. SUGARS (cont.) ANOTHER EXAMPLE: galactose
The chemical formula for galactose is C6 H12 O6
The structural formula for galactose is

8. GALACTOSE

9. SUGARS (cont.) ANOTHER EXAMPLE: fructose
The chemical formula for fructose is
C6 H12 O6
The structural formula for fructose is

10. FRUCTOSE

11. Compare & Contrast!

12. GLUCOSE, FRUCTOSE & GALACTOSE ALL HAVE THE SAME FORMULA - C6 H12 O6
What are molecules that have the SAME MOLECULAR FORMULA BUT DIFFERENT STRUCTURAL FORMULAS called?
ISOMERS!

13. How are disaccharides and polysaccharides made?
DEHYDRATION SYNTHESIS!!
It occurs when enzymes (catalysts) chemically combine small molecules (i.e., monomers) to make a large molecule (i.e., polymer)

14. DEHYDRATION SYNTHESIS (monomers polymer)
This is a reaction that occurs between two monosaccharides to make a di- or polysaccharide
EXAMPLE: glucose + fructose sucrose (table sugar) + water
The result of dehydration synthesis is a larger molecule + water

15. Dehydration Synthesis, cont.
Animation:

17. POLYSACCHARIDES
A very large molecule formed by joining MANY monosaccharides together using dehydration synthesis reactions
A biological polymer
Polysaccharides taste different from monosaccharides!

18. 3.7 Polysaccharides: Long chains of sugar monomers
Starch is a storage polysaccharide composed of glucose monomers and found in plants (bread, potatoes)
Glycogen is a storage polysaccharide composed of glucose, which is hydrolyzed by animals (us!!) when glucose is needed for ENERGY!!
Most mammals, including humans, do not have enzymes necessary to digest cellulose. Thus the energy in the glucose monomers is not available. Cows have solved this problem by harboring prokaryotes (bacteria) in their rumen that hydrolyze the cellulose of grass and hay to glucose monomers. The glucose can be used for energy as well as building blocks for other nutrients that nourish the cow. Likewise, termites cannot digest cellulose in wood, but the bacteria in their guts can, and so provide a meal for themselves as well as the termites
The text notes that cellulose is the most abundant organic molecule on Earth. Ask your students why this is true.
Student Misconceptions and Concerns
1. Consider reinforcing the three main sources of calories with food items that clearly represent each group. Bring clear examples to class as visual references. For example, a can of Coke or a bag of sugar for carbohydrates, a tub of margarine for lipids, and some beef jerky for protein (although some fat and carbohydrates might also be included).
Teaching Tips
1. A simple exercise demonstrates the enzymatic breakdown of starches into sugars. If students place an unsalted cracker in their mouths, holding it in their mouths while it mixes well with saliva, they might soon notice that a sweeter taste begins to emerge. The salivary enzyme amylase begins the digestion of starches into disaccharides, which may be degraded further by other enzymes. These disaccharides are the source of the sweet taste.
2. The text notes that cellulose is the most abundant organic molecule on Earth. Ask your students why this is true.
3. The cellophane wrap often used to package foods is a biodegradable material derived from cellulose. Consider challenging students to create a list of other cellulose-derived products (such as paper.)
4. An adult human may store about a half kilogram of glycogen in the liver and muscles of the body, depending upon recent dietary habits. A person who begins dieting might soon notice an immediate weight loss of 2–4 pounds (1–2 kilograms) over several days, reflecting reductions in stored glycogen, water, and intestinal contents (among other factors).
Copyright © 2009 Pearson Education, Inc.

19. 3.7 Polysaccharides, cont.
Cellulose is a polymer of glucose that forms plant cell walls; Can we digest it?
Chitin is a polysaccharide used by insects and crustaceans to build an exoskeleton

20. Starch granules in potato tuber cells STARCH Glucose monomer Glycogen
in muscle
tissue
GLYCOGEN
CELLULOSE
Cellulose fibrils in
a plant cell wall
Figure 3.7 Polysaccharides
Hydrogen bonds
Cellulose
molecules

21. GLYCOGEN-short term energy storage in the body

22. HYDROLYSIS: (polymer monomer)
Polysaccharides are broken down into smaller molecules (monosaccharides) by enzymes
Enzyme (a catalyst for the rxn) adds water to the molecules at the bond. A monomer is formed, and the polymer is shortened by 1 molecule.

23. Hydrolysis, cont. EXAMPLE: Amylase= enzyme in saliva
amylase (adds H20 to bond)
polysaccharides monosaccharide
(starchy taste) (sweet taste)

24. Animations!

25. Dehydration Synthesis & Hydrolysis
Dehydration Synthesis: a reaction that occurs between two “biomonomers” to make a biopolymer (hint… remove a water between the two monomers to join them…)
Hydrolysis: a reaction that adds water to a biopolymer to break it into smaller molecules (hint…add 2 H’s and an O to restore your two glucose molecules)