Question

Cells are constantly getting signals that determine whether they survive, grow and divide, differentiate, or die (see figure 16-6). Cells are grown in culture (outside of the body) for a variety of reasons- such as testing drug efficacy and determining the properties of different types of cancers (to name a couple). In order to culture cells, essential nutrients (carbohydrates, amino acids, vitamins, and hormones) need to be present, and these nutrients are provided by using different types of cell culturing media. You have three fibroblast cell lines from rats (see the image to the right), which are called A, B, C, and D. You know that these lines are different from each other, where line A produces the cell surface receptor called Diva. Cell line B does not produce Diva, but has the cell surface receptor called monster. Cell line C has both receptors present, Diva and Monster. Cell line D was your original cell line and never could proliferate, but you don’t know which cell surface receptors are present. You grow your cells in two types of media- one which contains growth factor G and one which does not contain growth factor G. You obtain the following results:

Cell line                  Factor G       Cell response

A                 - Factor G   cells do not proliferate

A       + Factor G   cells do not proliferate

   B       - Factor G   cells do not proliferate
B       + Factor G   cells do not proliferate

C       - Factor G   cells do not proliferate
C       + Factor G   cell proliferate

D       - Factor G   cells do not proliferate

D       + Factor G   cells do not proliferate

a)Which cell surface receptors do you think are present on cell line D? Explain your answer.

b)Explain the results of your experiment, in particular, what can you conclude about cell receptors, growth factor G and the different cell lines.

Answer 1

Ans a) In the cell line D which is also the original cell line, we can say that either DIVA or Monster cell surface receptor is present. It is because it is found that when these cell receptors are present in the cells, be it in absence or presence of the factor G, the cells will not proliferate.

Ans b) It is found that in cell A, cell surface receptor called Diva is present which helps in the proliferation of the cell in presence of Factor G but in its absence, there is no proliferation. Even in the second case, it is found that there is monster cell receptor but the cell does not proliferate even if factor G is present or absent. In case of the cell D, both receptors are presence and proliferation requires Factor G. It is found that in order for the cells to proliferate, it requires the Diva cell receptor along with the Factor G.