Question

In a protein molecules various amino acids are linked together by:
A. $\alpha$ - glycosidic bond
B. $\beta$- glycosidic bond
C. Peptide bond
D. Dative bond

Answer 1

Hint: Proteins are long chains of amino acids which are connected to each other to perform a variety of tasks. These proteins differ from each other in the sequence of amino acids.

Step by step answer: Proteins are large biomolecules or macromolecules which consist of one or more long chains of amino acid residues. They perform a vast variety of functions within organisms which include catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms and also transporting molecules from one location to another. These proteins differ from one another primarily in their sequence of amino acids which is dictated by the nucleotide sequence of their genes which usually results in protein folding into a specific 3D structure that determines its activity.
A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short size polypeptides which contain less than 20-30 residues are commonly called peptides and also sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds. The sequence of amino acid residues in a protein is defined by the sequence of genes which is encoded with genetic code. In general, the genetic code specifies 20 standard amino acids.
From the above information we get to know that amino acids in protein molecules are linked together by peptide bonds.

Therefore, the correct answer is option C.

Additional Information:
A Glycosidic bond is a type of covalent bond that joins a carbohydrate or sugar molecule to another group which may or may not be another carbohydrate. $\alpha$ - glycosidic bond is formed when both carbons have the same stereochemistry whereas a $\beta$ - glycosidic bond occurs when two carbons have different stereochemistry.
A dative bond is also known as coordinate covalent bond or dipolar bond. It is a kind of 2-center and 2-electron covalent bond in which two electrons derive from the same atom. The bonding of metal ions to ligands involves this kind of interaction.

Note: Peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of another molecule releasing a water molecule.