Question

Statement (I): Keratinocytes contain melanin pigment in the form of melanosomes.
Statement (II): Melanin pigment is produced by keratinocytes with the help of Tyrosinase enzyme.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are true.
• B. Both Statement (I) and Statement (II) are false.
• C. Statement (I) is true but Statement (II) is false.
• D. Statement (I) is false but Statement (II) is true.

Hint:

Remember: Melanocytes are the "factory" that produces melanin using the enzyme tyrosinase, while keratinocytes are the "consumers" or "storerooms" that receive and store the melanosomes.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Pigmentation of the skin is a collaborative process between two distinct cell types in the epidermis: melanocytes and keratinocytes.
Melanocytes are specialized pigment-producing cells, while keratinocytes make up the bulk of the epidermal structure.

Step 2: Detailed Explanation:
Let us evaluate Statement (I):
Although melanocytes synthesize melanin, they do not retain the majority of it.
Instead, mature melanin-containing organelles called melanosomes are transferred from the dendritic processes of melanocytes to adjacent keratinocytes through a process known as cytocrine secretion.
Once inside the keratinocytes, these melanosomes form a protective cap over the nucleus to shield DNA from UV radiation.
Thus, keratinocytes indeed contain melanin pigment in the form of melanosomes, making Statement (I) true.
Let us evaluate Statement (II):
Melanin synthesis (melanogenesis) occurs exclusively within melanocytes, not keratinocytes.
This biochemical pathway utilizes the rate-limiting enzyme tyrosinase to convert the amino acid L-tyrosine into dopaquinone, which eventually polymerizes into melanin.
Because keratinocytes lack the tyrosinase enzyme, they cannot produce melanin themselves.
Thus, Statement (II) is false.

Step 3: Final Answer:
Therefore, Statement (I) is true but Statement (II) is false, making (C) the correct option.