Explain the process of tissue cultures using healthy cells.

Answer:

To create a tissue culture, healthy cells are taken from a living organism and placed in a nutrientrich medium. These cells divide and reproduce through mitosis. They continue to grow and divide until they touch each other, a process known as contact inhibition. As a result, healthy cells form a layer one cell thick and then stop reproducing. Typically, normal cells undergo between 20 and 50 mitotic divisions in a culture before they permanently stop dividing.