In your lab you have several mouse cell lines growing in culture, designated cul
ID: 21298 • Letter: I
Question
In your lab you have several mouse cell lines growing in culture, designated culture A through culture D. Some of these cell lines are transformed and others are not. For each of the descriptions below, tell whether the cell line is transformed or normal, and explain your choice. If it is transformed, make an educated guess about the gene involved in the transformation.A. Cell line A is insensitive to the addition of growth factors to the medium. If the cells are exposed to damaging radiation, the growth curve is unaffected. Many of the cells have abnormal numbers of chromosomes.
B. Cell line B will not grow suspended in liquid media. The cells require a hard substrate, and then they only grow until one cell layer covers the substrate; they may grow a bit denser if growth factors are added to the medium. The cells lose their ability to move once the substrate is covered with a monolayer of cells.
C. Cell line C grows quickly and is quite successful when the cells are suspended in soft agar. The cells are impervious to the addition of serum to their medium. Upon exposure to damaging radiation, most of the cells undergo apoptosis.
D. Cell line D grows quickly and is impervious to DNA damaging radiation, entering cycle after cycle of mitosis even after large dosis of radiation. If transfected with DNA containing a gene for p53, these cells will undergo apoptosis.
Explanation / Answer
A. Transformed. Something affecting the growth cycle is mutated as in the presence of growth factors, it does not grow and in the presence of factors that should inhibit growth such as radiation, the growth is also not affected. It probably has something to do with the extra chromosomes. B. Not transformed. This is only depicting how a cell grows and it may be natural for it to do so. It is not a transformation C. Not transformed. Again, it is depicting how the cell grows. In response to radiation, which normally will kill cells, the cells updergo apoptosis (which is programmed cell death) as expected and hence is normal. D. Transformed. Something to the regulatory function of the cell cycle is likely mutations, probably p53. P53 is responsible for cell cycle suppression and prevents any growth of cells that has damaged DNA or is growing too fast. Since it is impervious to radiation, it is likely that the cell just doesn't sense that the dna is damage and just continues to grow (which it will if p53 is not functional). In the presence of p53 from a synthetic gene that is inserted, it will produce functional p53 which will cause programmed cell death after recognizing what has happened to the cell.