Imagine that a doctor is culturing two types of cells: one from a malignant melanoma and one from a normal skin sample. How would you expect these two cell populations to differ?

Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.

Explanation:

Telomerase can be described as enzymes which add the repetitive sequences called telomeres at the end of a chromosome. Telomeres can be described as repetitive sequences at the end of the chromosome which are involved in protecting the chromosome from any damage.

In a normal skin cell, the telomeres will shorten with time. But in a malignant skin cell, the telomerase will add the repetitive sequence again and again. The telomers will not be able to shorten.