Question

What is the correct pathway for the synthesis of skin pigment?
A. Tyrosine – melanin- Dopaquinone- Dopa
B. Tyrosine – Dopaquinone – Dopa- melanin
C. Dopa – Tyrosine – Dopaquinone – melanin
D. Tyrosine – Dopa – Melanin- Dopaquinone
E. Tyrosine – Dopaquinone- Dopa – Melanin

Answer 1

The natural skin pigment found in every organism is called melanin. The synthesis of melanin pigment starts in the liver. A specialized group of cells that produce the melanin pigments are called melanocytes. The entire process of synthesis of melanin pigments is called melanogenesis. The melanin pigments are the final product that starts with tyrosine.

Complete answer:
-The dark colouration of the skin is due to the present of melanin pigment in every organism.
-The group of cells that produce melanin pigments are called melanocytes which are present in the basal layer of the epidermis.
-The distribution and synthesis of this chemical process is called melanogenesis. This process starts in the liver.
-Basically there are $3$ types of melanin pigments. Eumelanin, pheomelanin, neuromelanin.
-The process of melanogenesis initiated by exposure of the UV radiation to the skin.
-The tyrosine is converted from phenylalanine with the help of phenylalanine hydroxylase. The L- Dopa is oxidised from L – tyrosine by the help of tyrosinase enzyme.
-It is then converted into Dopaquinone from Dopa.
-The Dopa then finally converted into eumelanin and pheomelanin.

Hence, the correct answer is option (B).

Additional information:
-Eumelanin plays an important role in skin protecting.
-Pheomelanin is largely responsible for colouring of hair.
-Neuromelanin is mostly found in the brain.

Note: Melanin is the pigment responsible for the skin colouration. The synthesis of the melanin pigments is called melanogenesis. This process starts in the liver from tyrosine to dopa to dopaquinone- melanin with the help of respective enzymes. Melanin is final by product of this chemical process. Eumelanin and pheomelanin are the final products.