62-Exercise 10 Questions I. Why does electrophoresis separate proteins? 2. Diffe
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62-Exercise 10 Questions I. Why does electrophoresis separate proteins? 2. Differentiate between plasma and serum. 3. Write the chemical formulas for pyruvate and lactate. How do they differ? 4. Under what conditions would a cell make lactate from pyruvate? Pyruvate from lactate? 5. Why would you expect LDH5 to predominate in skeletal muscle and LDH1 in cardiac muscle? 6. There are three creatine phosphokinase (CPK) isoenzymes: brain (CPK-BB), heart (CPK-MB), and muscle (CPK-MM). If a patient complains of chest pains, which form can be used to indi- cate whether the patient had a heart attack? Why? 7. There are four isoenzymes of alkaline phosphatase: blood, intestine, liver, and bone. What con- ditions might cause an elevated level of alkaline phosphatase? 8. Researchers have recently discovered that the white-rot fungus Pleurotus produces two isoen- zymes of manganese-oxidizng peroxidase. This enzyme is used to selectively remove lignin from grass. Why is the paper industry investigating the control mechanisms of each isoenzyme? 9. In plants, one isoenzyme of fructose 1,6-diphosphatase is found in the cytosol and another iso- enzyme is found in the chloroplast stroma. The enzymes catalyze the formation of sucrose from triose phosphate in the cytosol and starch from triose phosphate in the stroma. The cytosolic en- zyme is active in the presence of high triose phosphate and the stromal enzyme is activated by light. Propose a reason for the two different methods of activation.Explanation / Answer
Ans. 1
Before beginning with the answer we should learn what does the electrophoresis means. Well, electrophoresis is a standard laboratory technique by which charged molecules are transferred through a solvent by an electrical feild. Well we might find it strange but it's true that both the proteins and the nucleic acids can be separated by this process. This is made possible because in human body, each biological molecule carries a net charge despite of any pH other than their isoelectric point and will migrate to their charge density. This is the reason why proteins are separated under the presence of an electrical field.
Ans. 2
A very common misconception is seen where people believed that plasma and serum are same thing. Well this is not true. They are two different substances in a common solution containing constituents which make them different and unique from each other. When we consider blood, it is composed of RBCs, WBCs, platelets and watery content. The basic watery content of the blood is called plasma. If we make stand still a sample of blood for an hour we will observe that there is precipitation of red cells and white cells and a straw colored fluid is present above it. This liquid is plasma which contains s fibrinogen, a clotting factor which is required for blood clotting.
Now, serum is plasma without the clotting factors i.e., fibrinogen. So, serum does not clot on standing.
The difference? Well both are derivatives of blood. Both contains electrolytes, other proteins, drugs, hormones and toxins. Both can be obtained by centrifuging and both can be used for diagnostic as well as therapeutic purposes. But plasma is serum with fibrinogen and other clotting factors, so plasma tends to discolor on standing, whereas serum does not. Separation of plasma is relatively easy and cheap whereas serum separation requires time and is expensive.
In other words, we can say that plasma is the crude product of precipitation of blood whereas serum is the refined plasma minus the fibrinogen and other clotting factors.
Ans. 3
Chemical formula for pyruvate = C3H4O3
Chemical formula for lactate = C3H6O3
The difference? Well no such specific difference, except that pyruvate is the electron acceptor during fermentation of lactic acid. When sufficient oxygen is not available for further oxidation of pyruvate in glycolysis, then pyruvate is converted into lactate by lactate dehyrogenase enzyme.
Ans. 4
Under anaerobic conditions that is in the absence of oxygen, pyruvate is converted into lactate.
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