Question

Proteins are made of
(a) Disaccharides
(b)Amino acids
(c) Monosaccharides
(d)None of the above

Answer 1

Hint: Each protein molecule is an unbranched linear polymer, formed by the condensation polymerization of small monomer units through peptide bonding.

Complete answer:
Proteins are formed of C, H, O, and N, with trace amounts of S and P in some cases. Sometimes, they may contain Cu, Fe, Mg, Zn, and I also. All these elements enter into combinations and form amino acids. As many as 300 kinds of amino acids are known to exist in nature. Of these, 20 kinds enter into the formation of endless varieties of natural proteins. These amino acids are called proteinogenic amino acids, or standard amino acids. They form the units of protein structure and are ultimately responsible for the specificity and variability of living systems. They undergo condensation polymerization through covalent peptide bonding and form polypeptide chains. One or more such chains form a protein molecule. Of these 20 proteinogenic amino acids, the first discovered one is asparagine and the last discovered one is threonine. Proteins are the much abundant structural and functional organic constituents of the living matter. They largely determine the
functional properties of living matter, serves as the chief regulators of life activities, and form the organic basis of life. Their roles as the main structural and functional molecules of the cells, and also as chief regulators of life processes, are remarkable. They have extreme specificity in action, which is characteristic of life itself.

Additional Information:
-Proteins are complex, nitrogen-containing macromolecules. Chemically, they are amphoteric polyelectrolytes, with colloidal, osmotic, and buffering properties.
- Since proteins are macromolecules, they are long-chain molecules. In gross structure, proteins are mostly covalently cross-linked peptide groups.
-Recently, two more amino acids have also been included under the list of proteinogenic amino acids. They are selenocysteine and pyrrolysine.

Note: -selenocysteine is found at the active site of certain enzymes, called selenoproteins. It is unusual in having the trace element selenium in place of the sulfur of cysteine.
-Selenocysteine is specified by the codon UGA, which is normally a stop codon that terminates genetic translation.
-Pyrrolysine is also believed to be coded by UGA, but the proteins in which they are present are not definitely understood.