Lab: Diffusion Across a Semi-permeable Membrane Answers

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.

Tissue cultures of cancer cells involve removing cells from a living organism and placing them in a nutrientrich environment for growth. Cancer cells in a culture grow at an uncontrolled rate because they do not respond to normal regulatory signals. Unlike healthy cells, they lack contact inhibition, so they will continue to divide and pile up in multiple layers even after touching adjacent cells. Furthermore, cancer cells are often immortal in culture, meaning they can undergo mitotic divisions an unlimited number of times.

Using tissue cultures to study cancer medications is beneficial because it allows researchers to test drugs on live cells without exposing human patients to potentially harmful or ineffective treatments. Since cancer cells often continue to divide rapidly in a lab setting, scientists can efficiently test multiple medications or combinations of treatments at once. Once a specific medication is proven effective at inhibiting cancer cell growth in the culture, it can then be prioritized for clinical use, making the development process safer and more targeted.