Use the following article to answer these questions httpwwwn

Use the following article to answer these questions:

http://www.nature.com/scitable/topicpage/nutrient-utilization-in-humans-metabolism-pathways-14234029

1)This article points out that a major misconception, especially for many undergraduates, is that human cells only use glucose as a fuel source. In fact, all three major absorbed end products of the digestion of carbohydrates, lipids and proteins can be utilized by most cells for the generation of ATP. What serves as the major entry point (mechanism) for these different classes of molecules that makes it possible for them to serve as fuel for ATP production? Why does this mechanism not work in the absence of oxygen? Hint: consider glycolysis and fermentation.

2)Although many of the approximately 200 cell types in the human body can utilize all three major classes of food molecules for energy, not all can. Why? Provide an example.

Solution

1) answer is liver is considered as central metabolic clearing house. it distributes the all these three types of nutrients like carbohydrates, lipids and proteins into diffrent parts of body. gluocose mainly produce energy(ATP) by glycolysis. All these three nutrients gets degraded to generate ATP by TCA cycle ( tricarboxylic acid cycle produces Acetyl co A ) is main central mechanism involved. it is otherwise known as Kreb\'s cycle.

mitochondrial matrix is necessary to provide enzymes necessary above reactions( centers for aerobic conditions). In the absence of oxygen ( fermentation) these reactions does not takes place due to lack of mitochondria.

2) brain, erythrocytes, retina, utilizes glucose for main energy source, they can not utilize other nurtients due to lack of mitochondria cells which is location ceneter for enzyems provide for degradatio of lipids and proteins