Concept explainers
How are proteins formed and how can we describe their structures?
Interpretation:
The formation of proteins and their structure are to be described.
Concept Introduction:
A protein unit is composed of a number of smaller individual units called amino acids. Amino acids possess both the amino and carboxylic acid groups. Amino acids are linked together through a peptide bond which leads to the formation of proteins.
Explanation of Solution
The amino acids perform many biological functions including protein synthesis, which is their primary function. Protein synthesis is a complex process controlled by DNA.
The carboxylic acid group of one amino acid reacts with the amino group of another, releasing a water molecule from these two amino acids results in the formation of a peptide bond. The resultant molecule is called a dipeptide. The dipeptide reacts with another amino acid, forming as tripeptide. If many amino acids are linked in a peptide chain, it is called polypeptide. A polypeptide with a molar mass more than
There are four different levels of protein structure as follows:
Primary structure: This provides the sequence of amino acids in polypeptide chain. The end of the polypeptide chain which has free amine group is called amino terminus(N-terminus) whereas the other end with free carboxylic group is called carboxylic terminus(C-terminus).
Secondary structure: There are two types of secondary structure- the α-helix and the β-sheets. The hydrogen bond donors and acceptors in the peptide backbone of α-helix and β-sheets are saturated.
Tertiary structure: It is a compact three-dimensional structure of folded α-helix and β-sheets.
Quaternary structure: Two or more polypeptides in three-dimensional structure aggregate together to form a quaternary structure.
Proteins are formed from the combination of a number of amino acids. The structure of protein is described in four different ways on the basis of the arrangement of aminoacids and peptide chains.
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Chapter 17 Solutions
EBK INTRODUCTION TO CHEMISTRY
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