Question

The amino acids which are not synthesized in our body are called:
A. Nonessential
B. Deaminated
C. Proteinaceous
D. Essential

Answer 1

Hint: Amino acids are the building blocks of proteins. They are required for many metabolic reactions in the body. Amino acids which are not synthesized in our body are supplemented by the food that we eat.

Complete answer: Essential amino acids are amino acids that our body cannot manufacture on its own. They can’t synthesize these enzymes as they lack the enzymes necessary to create them from other biological molecules. Hence, these essential amino acids must be supplied in the diet every day.
The essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The best dietary sources for obtaining these essential amino acids include meat, eggs, tofu, soy, buckwheat, quinoa, and dairy products. Casein is a protein that is present in milk. It has all the essential amino acids, hence, cow milk has the highest concentrations of casein which is beneficial to the growth and development of infants. Proteins can be classified based on their nutritional value as:
a) Rich proteins: They are also called complete/first-class proteins. They contain all the essential amino acids in the required and precise proportions. On supplying these proteins in the diet, children will grow healthy.
b) Incomplete proteins: They lack one of the essential amino acids. They cannot promote satisfactory body growth in children. They may be able to sustain body weight in adults. For example, proteins in pulses are deficient in methionine and proteins of cereals lack in lysine.
c) Poor Proteins: They lack in many of the essential amino acids. A diet based on these proteins will not be able to sustain even the original body weight. Zein from corn lacks tryptophan and lysine
Hence, the correct answer is option D.

Note: Conditional amino acids are those that are usually not essential. They are required only in times of illness and stress. The conditional amino acids include arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine.