Question

Which one of the following is a milk protein?
A. Lactogen
B. Myosin
C. Casein
D. Pepsin

Answer 1

Hint: Proteins are the macromolecules which are composed of amino acids as monomeric units. Amino acids are joined with the help of peptide bonds to form protein molecules. There are 20 amino acids that are responsible for the formation of all types of proteins. Proteins are the biomolecules that are needed for performing various functions of life.

Complete Answer:
A. Lactogen: Lactogen is a milk sugar.
- Milk sugar is slightly sweet in taste.
- The lactogen is composed of glucose and galactose subunits.
- The compound lactogen is a white, water soluble, non hygroscopic solid.
- It is used in the food industry for the commercial purpose.

B. Myosin: Myosin is a motor protein.
- The function of myosin is in muscle contraction and a wide range of other motility processes in eukaryotes.
- Myosin are the ATP (adenosine triphosphate) - dependent proteins.
- They are responsible for action-based motility.
- Myosin is found in the cells of both striated muscle and smooth muscle tissues.

C. Casein: Casein is a milk protein.
- Milk contains 9 essential amino acids that are required by the humans.
- Milk proteins are synthesized in the mammary glands of the females.
- The casein family of milk proteins consist of several types and each of the casein has its own amino acid composition, functional properties and genetic variations.
- Casein protein is a good source of Calcium which helps in keeping the bones strong.

D. Pepsin: Pepsin is an endopeptidase.
- Pepsin helps in the breakdown of protein molecules into the smaller peptides.
- Pepsin is produced in the chief cells of the stomach lining.
- It is the main digestive enzyme in the digestive system of human beings.
- It helps in the digestion of proteins.
- Pepsin is an aspartic protease.
- Proenzyme of the pepsin is pepsinogen.
- Pepsinogen is secreted by the chief cells of the stomach and when it gets mixed with hydrochloric acids, it gets activated to become pepsin.

Hence, option C is the correct option for this question.

Note: Some proteins also act as the enzymes. Enzymes are the catalysts that can increase the rate of any reaction without their expenditure. They provide a new path for the reaction to occur so that reaction can proceed in a faster way.