Amino Acids and Proteins Multiple Choice Questions(MCQs)& Answers
CONCEPTS & THEORIES
amino-acids-and-proteins
About Amino Acids and Proteins
Amino acids are organic compounds that contain amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid.Amino acids play central roles both as building blocks of proteins and as intermediates in metabolism. The 20 amino acids that are found within proteins convey a vast array of chemical versatility.
Proteins are among the most abundant organic molecules in living systems and are way more diverse in structure and function than other classes of macromolecules. A single cell can contain thousands of proteins, each with a unique function. Although their structures, like their functions, vary greatly, all proteins are made up of one or more chains of amino acids.
Essential amino acids
Humans can produce 10 of the 20 amino acids. The others must be supplied in the food. Failure to obtain enough of even 1 of the 10 essential amino acids, those that we cannot make, results in degradation of the body’s proteins—muscle and so forth—to obtain the one amino acid that is needed. Unlike fat and starch, the human body does not store excess amino acids for later use—the amino acids must be in the food every day.
Acid-Base Properties
Another important feature of free amino acids is the existence of both a basic and an acidic group at the ?-carbon. Compounds such as amino acids that can act as either an acid or a base are called amphoteric.
QUESTIONS
Amino Acids and Proteins Multiple Choice Questions(MCQs)& Answers
7
Which of the following amino acid will be absent in ? (alpha) helix structure of protein?
Answer: Proline
15
The two amino acids having R groups with a negative net charge at pH 7.0 are
Answer: Aspartate and glutamate
16
Identify the amino acids containing nonpolar, aliphatic R groups
Answer: Glycine, alanine, leucine
17
Among the 20 standard proteins coding amino acids, which one is least occurs in proteins?
Answer: Tryptophan
19
Bacteria prefer to use the codon CGA instead of AGA to code for Arginine. This is an example for _____.
Answer: Nullomers
20
Name the amino acid, which exists in two non-superimposable mirror images of each other.
Answer: Enantiomer
21
A solution of L-alanine (4.0g/50 ml of 6 N HCl) has a rotation of +1.61° in a 2dm polarimeter tube. Calculate the specific rotation of L-alanine in 6 N HCl.
Answer: +10.1°
27
Which of the following is a true statement?
Answer: Tryptophan and tyrosine are significantly more polar than phenylalanine