The correct structure of histidine in a strongly acidic solution (pH=2) is
The Correct Option is A
Solution and Explanation
Zwitter ionic form
$pIn = 7.59$
Top Questions on Proteins
- The $\alpha$-amino acids are the building blocks of proteins. All $\alpha$-amino acids exist as zwitter ions due to which they show amphoteric behaviour. All amino acids are joined through peptide bonds. Proteins are broadly classified as globular proteins and fibrous proteins. Globular proteins are water soluble, whereas fibrous proteins are not. The complete structure of protein is discussed at four different levels i.e. primary, secondary, tertiary and quaternary structures. Protein loses its biological activity in denatured form.
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Concepts Used:
Proteins
An essential part of every cell in our body, protein is one of the three macronutrients which is required by our body in larger amounts. Proteins are made up of linear chains of smaller units called amino acids. Every biochemical process that takes place inside our bodies is possible because of these proteins. Proteins are 3-dimensional structures that are assembled with different amino acid sequences.
Functions of Protein
Proteins are used in many ways. Some of their functions are:
- Enzymes: Most of the important chemical reactions which take place inside a cell are mostly carried out by enzymes. They also play a role in regenerating and creating DNA molecules and carrying out complex processes.
- Hormonal Regulation: Proteins create various types of hormones that help in balancing the components of the body. For example, hormones like insulin help in regulating blood sugar and secretin. The formation of digestive juices essential for the whole digestion process is also possible because of hormones.
- Protection: Being the main constituent of antibodies, proteins protect our body against antigens and pathogens thus preventing infections.
- Energy: Proteins are one the most essential sources of energy required for our body movements. The right amount of proteins should be consumed so that they can be turned into energy.
- Structural functions: Proteins are the building blocks of the body. They are required for the growth, development, healing, and repair of tissues. Proteins are essential in order to strengthen various structures like hair, skin, and muscles. It is also present in the outer membrane of all cells in the human body.
Classification of Protein
Proteins are classified on the basis of:
- Shape
- Constitution
- Nature of Molecules
Protein Structure
A protein molecule is made from a long chain of amino acids, each linked to its neighbor through a covalent peptide bond. The structure of proteins are divided into four types:
- Primary Structure
- Secondary Structure
- Tertiary Sector
- Quaternary Structure