Final answer:
The cells nearest to the surface that make up the outer portion of the skin are called keratinocytes. They are found in the epidermis, the outermost layer of the skin.
Step-by-step explanation:
The cells nearest to the surface that make up the outer portion of the skin are called keratinocytes. These cells are found in the epidermis, the outermost layer of the skin. Keratinocytes continuously divide through mitosis at the bottom of the epidermis and move up towards the skin surface, producing keratin and eventually forming a protective layer called the stratum corneum.