Question

"Melanocytes _____________.

A store melanin in melanosomes
B secrete melanin from the basal surface
C manufacture melanin from the amino acid alanine
D are located in the stratum corneum"

Answer 1

Melanocytes, located in the stratum basale, produce melanin from the amino acid tyrosine and store it in melanosomes. This melanin is then transferred to keratinocytes to protect the skin from UV radiation.

Step-by-step explanation:

Melanocytes are cells found in the stratum basale of the epidermis. Their primary function is to manufacture the pigment melanin from the amino acid tyrosine, not alanine. Melanin is stored in organelles called melanosomes. Once melanin is produced, it is transferred to the nearby keratinocytes which form the main cell type of the epidermis. These melanin-filled keratinocytes help protect deeper layers of the skin from UV radiation by absorbing and dissipating the harmful UV rays, thus preventing DNA damage and contributing to skin pigmentation.

As for the four options presented in the question:

1. Melanocytes store melanin in melanosomes.
2. Melanocytes do not directly secrete melanin from the basal surface but transfer it to keratinocytes.
3. Melanocytes manufacture melanin from the amino acid tyrosine, not alanine.
4. Melanocytes are located in the stratum basale, not in the stratum corneum.