why do most cells of an adult multicellular organism not divide? why might they be stimulated to divide?

Question

how does this relate to the development of cancers?

Answer 1

First off, cancer is an otherwise perfectly healthy cell that starts reproducing but doesn't stop when it should.

Most cells in adult multicellular organisms don't divide because more cells aren't needed. Take yourself as an example: Once you stop growing your heart has all it needs to function, your lungs are big enough, and you have plenty of skin. If your cells didn't stop dividing you would keep growing, such is the case in people suffering from Gigantism.

When cell loss (through damage or 'old age') is detected a chemical switch is flipped and surrounding cells are stimulated to divide in order fill the gap. Once the gap has been filled cells are supposed to stop reproducing.

If that "switch" gets broken or stuck in the "on" position, the cells won't stop dividing, and their offspring don't stop dividing. The new cells pile up on each other, forming a lump, and they'll keep dividing, making more cells, and more, and more, and more. That is cancer.

Answer 2

Cell division (actually the CELL CYCLE) is regulated by an incredibly complicated series of genes and proteins and signaling. But in the simplest terms, cells have genes called "oncogenes" and "tumor supressor genes", of which the former causes cell division, and the latter stops cell division.

In all cells, both of these kinds of genes are functioning all the time, but are regulated by various pathways (by extracellular signaling, and even factors from within the cell).

An oncogene we know a lot about is called RAS, and a tumor suppressor we know a lot about is p53. Basically in cancer, and this is just two examples: (1) RAS (an oncogene) activity is unregulated, thus the cell loses control of the cell cycle and divides uncontrollably. (2) p53 activity is lost, and thus we lose "tumor suppressor" function, and the cell divides uncontrollably.

The problems with cancers are not always these genes themselves, but the pathways that regulate them (regulate their transcription for example). There are many many many different things that can upset these pathways, and thats why cancer is so so difficult to fight/prevent.

Hope this helps!

Answer 3

Actually a lot of them do divide. You are continuously making new blood cells and new cells of the digestive tract. As far as what makes other typically non-dividing cells divide, that is a complicated answer. It depends on the cell type. However, certain steroids or other cellular growth factors can cause cells to divide when they would otherwise not. Certain cancer agents can mutate cells so that they start dividing very rapidly. Hope that helps.

Answer 4

it is obviously fake. merely think of approximately people, we lose and replace cells till the day we die. If cells now no longer replaced broken cells as quickly as we reached person length, there is not any way we could have the potential to recover from injuries or surgical treatment. some consumer-friendly experience and concept could have extra you to the comparable end.

Answer 5

cuz if it did we would be evolving like crazy