Since the goal of all this is ATP, why not check that out first. Read the "easy" material. Then come back to the ATP link.

Which should you know?

Glucose

When oxidized in the body in the process called metabolism, glucose produces carbon dioxide, water, and some nitrogen compounds and in the process provides energy which can be used by the cells. The energy yield is about 686 kilocalories (2870 kilojoules) per mole which can be used to do work or help keep the body warm. This energy figure is the change in Gibbs free energy DG in the reaction, the measure of the maximum amount of work obtainable from the reaction. As a primary energy source in the body, it requires no digestion and is often provided intravenously to persons in hospitals as a nutrient.

Energy from glucose is obtained from the oxidation reaction

C₆H₁₂O₆ + 6O₂ --> 6CO₂ + 6H₂O

where a mole of glucose (about 180 grams) reacts with six moles of O₂ with an energy yield DG = 2870 kJ. The six moles of oxygen at STP would occupy 6 x 22.4L = 134 liters. The energy yield from glucose is often stated as the yield per liter of oxygen, which would be 5.1 kcal per liter or 21.4 kJ per liter. 

This energy yield could be measured by actually burning the glucose and measuring the energy liberated in a calorimeter. But in living organisms, the oxidation of glucose contributes to a series of complex biochemical reactions which provides the energy needed by cells. In animal cells these processes have been modeled in the Krebs cycle. 

A major part of the use of the energy from glucose oxidation is the conversion of ADP to ATP, with the energy-rich molecule ATP being subsequently used as the energy currency of the cell.

Glucose is manufactured by plants with the aid of energy from the sun in the process called photosynthesis. This synthesis is carried out in the small energy factories called chloroplasts in plant leaves. 

The chloroplasts capture the energy from light and fabricate glucose molecules from carbon dioxide from the air and water from the soil.

from http://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/

Starches

Starches are carbohydrates in which 300 to 1000 glucose units join together. It is a polysaccharide which plants use to store energy for later use. Starch forms in grains with an insoluble outer layer which remain in the cell where it is formed until the energy is needed. Then it can be broken down into soluble glucose units. Starches are smaller than cellulose units, and can be more readily used for energy. In animals, the equivalent of starches is glycogen, which can be stored in the muscles or in the liver for later use.

Foods such as potatoes, rice, corn and wheat contain starch granules which are important energy sources for humans. The human digestive process breaks down the starches into glucose units with the aid of enzymes, and those glucose molecules can circulate in the blood stream as an energy source. Tillery, et al. point out an interesting example of this enzyme-catalyzed breakdown process. If you chew on a piece of bread for a while, it will begin to taste sweet because the enzymes in saliva are already beginning to break down the starch into glucose, a sugar. from: http://hyperphysics.phy-astr.gsu.edu/hbase/organic/carb.html#c1

Cellulose

Cellulose is a form of carbohydrate in which some 1500 glucose rings chain together. It is the chief constituent of cell walls in living organisms. Wood is mostly cellulose, making cellulose the most abundant type of organic compound on the Earth.

Cellulose molecules tend to be straight chains, and the fibers which result from collections of cellulose molecules have the strength to form the supporting structures of plants. Even though human digestion cannot break down cellulose for use as a food, animals such as cattle and termites rely on the energy content of cellulose. They have protozoa and bacteria with the necessary enzymes in their digestive systems. Cellulose in the human diet is needed for fiber. Also from http://hyperphysics.phy-astr.gsu.edu/hbase/organic/carb.html#c1

View this site on "How Diabetes Works." Be able to answer the following questions:

1. The incidence of diabetes mellitus in the U.S. has (increased/decreased/stayed the same) in the past 50 years. Be able to choose the word that makes the sentence correct.

2. Based on your answer to question number 1 do you think diabetes is purely genetic? Yes or No and Why?

3. Has anyone actually died from diabetes or is merely an inconvenience?

4. What function does glucose serve in the body?

5. Where does the glucose in your blood come from?

6. Why does the normal body maintain blood glucose levels in a particular range?

7. What elements are present in glucose?

8. Two hormones are primarily responsible for maintaining blood glucose levels. What are those two hormones and in what organ are they produced?

9. What specific part of the organ, and what specific cells of that organ, produce the two hormones responsible for maintaining blood glucose levels? Which cells produce which hormone?

10. Again, list the hormones. This time give the function of each.

11. The release of which hormone is stimulated after a meal?

12. The release of which hormone is stimulated if hours have passed between meals?

13. Compare and contrast type 1 with type 2 diabetes.

14. What is gestational diabetes?

15. What 10 symptoms are common to diabetics?

16. What does insulin resistance mean?

17. Why is thirst one of the major symptoms of diabetes? What stimulates the frequent thirst?

18. Why might a diabetic's hands and feet feel cold?

19. How can some cases of type 2 diabetes be prevented?

20. What is hypoglycemia and what are some of the signs and symptoms of hypoglycemia?

21. There are medicines for type 2 diabetes. They work in one or a combination of six ways. What are the six ways in which they function?

Also read "Paean to the pancreas" from Dream magazine, a publication of the Boston Children's Hospital.

And Quick-burning carbs may cause fatty liver a news release from the hospital.

Read in detail about the action of beta cells http://www.betacell.org/content/articles/print.php?aid=1

Now, if you want to know more you can go to a diabetes mellitus pathology tutorial.

© 2005 STCC Foundation Press
Author:  Michele Nash