A. Bacteria in the small intestine ferment lactose and produce gas. B. Lactose i

Question

A. Bacteria in the small intestine ferment lactose and produce gas.

B. Lactose is a polar molecule and cannot cross the intestinal membrane without a transport protein.

C. Transport proteins in the intestinal lumen are specific for monosaccharides.

D. Excess lactose osmotically increases water flow into the small intestine.

A.   Jamal should not follow Mike's advice. Although there would not be any negative consequences if Jamal takes the lactase, it is best if he consults his physician before trying any new medications in case his disorder causes him to have allergic reactions to commercial enzymes.

B.   Jamal should follow Mike's advice. Both disorders are linked to milk consumption. Lactase makes milk easier to digest and it will allow Jamal to try the milkshake without any negative consequences.

C.   Jamal should follow Mike's advice. Both disorders are linked to an enzyme deficiency in similar pathways. Ingesting an additional source of an enzyme in one part of the pathway will stimulate the flux of the pathway and allow Jamal to consume milk products.

D.   Jamal should not follow Mike's advice. If Jamal ingests lactase along with the milkshake, it could cause harmful side effects.

Explanation / Answer

1. Lactose intolerance is caused by lactase deficiency in the body. This prevents the body from breaking down lactose into glucose and galactose in the small intestine (where this break down normally occurs). Only monosaccharides can be transported across the intestinal lumen. Since the lactose is not broken down it is used by the microorganisms present in the colon and fermented to lactic acid, generating methane and hydrogen gas alondside it. It is these gases that create disturbances. The lactic acid is osmotically active and hence increases water flow inside the intestine. This causes diarrhea.

From this we can see that the correct optioins are - A, C and D. However, since A and D do not answer the question, these are not the answers. Therefore, the best answer is C.

2. Galactosemia is a genetic disorder that inhibits the ability of galactose metabolism by the individual's body. This leads to the accumulation of galactose, which then serves as a substrate for other enzymes resulting in products like galactitol (on reduction) or galactonate (on oxidation).

In the case of lactose metabolism, glucose and galactose are produced. In the case of galactosemia, the lactase works and lacotse is broken down. However, the resulting galactose accumulates in the small intestine. So, the lactase pill will have no effect on Jamal and should not try to have one (since there is still some probability of allergic reactions).So, option A is the correct answer.

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