If an essential amino acid is absent from the diet a the liv

If an essential amino acid is absent from the diet

a) the liver will produce the amino acid by transferring an amine from glutamine to the corresponding alpha-keto acid

b) muscle protein will be degraded to scavenge the needed amino acid

c) nitrogen will be conserved by recycling into glutamate or alanine

The polypeptide below, when subjected to electorphoresis Asp-Lys-Val-Pro-Glu-Phe-Met-Arg-Ala

a) will migrate towards the cathode at pH 7

b) will remain stationary at pH 7

c) will migrate towards the anode at pH 7

Solution

Please find the answers below:

Part 1: Choice b (an essential amino acid is the one which cannot be synthesized by any of the biological processes. When a person is deprived of essential amino acids, the first response of the body is to gather the biomolecules which are enriched with those amino acids. Breakdown of muscles to yield proteins and their further breakdown into amino acids and nitrogenous compounds is a general phenomenon to perform this function. For example, in persons who are fasting for long time, excessive ketone bodies are diagnosed in the urine. This happens because thier muscular mass is decreasing due to breakdown of essential proteins to yield nitrogenous compounds and amino acids)

Part 2: Choice b (It can be noted that the polypeptide contains almost equal number of acidic and basic amino acids. This will result in a net neutral charge on it. Thus, since the net charge on the protein is nearly 7, it will remain stationary at pH 7. If there were more basic amino acids, the net charge would have been negative and the polypeptide would have migrated towards the positive elctrode. On the other hand,if there were more acidic amino acids, the net charge would have been positive and the polypeptide would have migrated towards negative elctrode.)