Phys Eco exam 1 Nutrients and Cellular Energy #3

What is the major role of carbohydrates?

They are a primary energy source in plants and are also required for CNS function and metabolism.

What are examples of soluble carbohydrates?

Glucose, fructose, sucrose, lactose, and starch.

What are structural carbohydrates?

Cell-wall carbohydrates such as cellulose and hemicellulose.

What are the three glucose polymers mentioned in lecture?

Starch, glycogen, and cellulose.

What are proteins?

Polymers of amino acids (polypeptides).

How can dietary amino acids be used?

They can be used to make other proteins or for energy.

How does the energy per gram of protein compare with carbohydrates?

They provide the same amount of energy per gram according to lecture.

What are lipids?

Molecules containing at least one fatty acid with substantial energy stored in C-H bonds.

What is a triglyceride?

Three fatty acids linked to a glycerol molecule; used for energy storage.

How energy-dense are fats?

Approximately twice as energy dense as proteins or carbohydrates.

What are phospholipids used for?

Membranes. They consist of glycerol linked to two fatty acids and one phosphate group and were noted as important in hibernation.

What is the function of waxes?

Waterproofing, making them important in water balance.

Glycolysis

6-carbon glucose is broken into 3-carbon pyruvate.

What happens to pyruvate before the Krebs cycle?

3-carbon pyruvate is converted into 2-carbon acetyl-CoA.

What happens to acetyl-CoA in the Krebs cycle?

It is ultimately broken into CO₂ and its energy is transferred to electron carriers.

What does electron-transfer phosphorylation do?

Produces ATP and requires oxygen.

What must happen to food before it can be used for energy?

It must be converted into a form capable of entering glycolysis or the Krebs cycle.

How do nonstructural carbohydrates enter energy metabolism?

Starch, glycogen, glucose, and other simple sugars are easily modified to enter glycolysis.

How does glycerol enter energy metabolism?

It can be converted into pyruvate and then enter the Krebs cycle.

How do fatty acids enter energy metabolism?

They are broken into 2-carbon pieces that form acetyl-CoA.

How can proteins be used for energy?

Proteins → amino acids → nitrogen removed and converted to urea → carbon portion enters the Krebs cycle for energy.

What else can happen to some amino acids after nitrogen removal?

They can be converted into glucose.