Chapter 7 Metabolism: Transformations and Interactions

Metabolism: The sum total of all the chemical reactions that go on in living cells.

Energy metabolism: Includes all the chemical reactions by which the body obtains and spends the energy from food. Review: 3 energy nutrients Carbs broken into glucose Fats broken into glycerol + 3 fatty acids Protein broken into amino acids
These basics components are absorbed into the body to provide energy

Anabolism: reactions in which small molecules are put together to build larger one. This building process requires energy.

Catabolism: reactions in which large molecules are broken down to smaller ones. The breaking down releases energy.

This energy is captured by Adenosine Triphosphate (ATP) - A common high energy compound composed of a purine (adenine), a sugar (ribose), and three phosphate groups. - ATP’s are the go between molecules or energy carriers

Whenever cells do any work that requires energy hydrolytic reactions readily break these high-energy bonds of ATP splitting off one or two phosphate groups and releasing their energy.

Enzymes: are protein catalysts. Proteins that facilitate chemical reactions without being changed in the process. The “helper”

Coenzymes: Complex organic molecules that work with enzymes to facilitate the enzyme’s activity. Many coenzymes have B vitamins as part of their structures. Think of these guys as the “helper’s helper.”

Pathways of where the compounds go.

About 66% to 75% of our total caloric needs come from unconscious activity and thermic effect of food.
50%-65% Basal Metabolism
10% Thermic effect of food
30%-50% Physical Activity

-If 2000 calorie diet that means approximately 1,300 to 1,500 calories is need for these activities. -What are these activities? Brain and nerve functions Breathing Digestion Heart beats, etc.
*** The brain requires glucose for energy. If non available, the system begins to catabolize glycogen store, fat, and muscle for energy.

Fasting is unhealthy as you can see in the above pathways chart. Why? Our system will produce Ketones
Ketone bodies: are compounds produced during the incomplete breakdown of fat when glucose is not available.
Ketones are: Unhealthy Toxic to the system Suppress appetite
As this occurs, the metabolism slows down to move into a state of conservation. This is why starvation diets are unhealthy. Little fat is burned, with the lose coming mostly for protein and water.
Low carb diets produce ketosis.
High proteins diets are do not work as well do to a decrease in vitamins and mineral which can lead to other health issues.

So how does this take place???
This process is like a machine where the energy yielding nutrients are converted and broken down.

First we take our 3 nutrients and look at the molecular structure. “The Ingredients”
Glucose

Glycerol

1 Fatty Acid

Amino Acids

Now we take these ingredients and feed them into the: 1. Pyruvate Process 2. Acetyl CoA Process

These two processes are converting the ingredients to small chains.
The outcome of the Pyruvate will yield a by product of a chain of three carbons
The outcome of the Aceytle CoA will yield a by product of a chain of two carbons.
*each time this occurs energy is released due to the breaking down of these ingredients.

It looks like this:

From the Acetyl CoA then to the TCA cycle:
A series of