Thread: Question about cell reproduction

Hello all,

I'm new to these forums and I'm not a scientist, but I am eager to learn. So please go easy on me if my question seems a bit daft, if my terminology is suspect, or if my understanding of how it all works is way off track.

I understand that DNA, chromosomes and genes contain the information which tells a cell what type of cell to be, how long it should live for, how frequently it should reproduce and all that kind of thing.

It seems baffling that all this information on how a cell should grow, behave and reproduce could be stored in such a relatively small space. But I can accept that there is a lot more going on at a microscopic (subatomic?) level than I can imagine. So far, I can suspend disbelief.

What I really cannot get my head around is this: When cells reproduce, the child cell doesn't always have to be an exact copy of the parent cell. For instance, skin cells presumably sometimes produce nerve cells, eye wall cells produce iris cells, etc etc. As far as my (very limited) understanding goes, this is achieved by the parent cell modifying the DNA markers of the child cell. How does the parent cell know to do this?

But how does a cell know to do this? Even on a simple parent-child cell division this seems incredible. But considering the enormous amount of information that must be passed on all the way from an original embryonic cell to, say, a brain cell, how on earth is this possible?

It almost seems as if cells just know what to do. They seem to know exactly what they should do, how they should behave, what their function is, from their original instructions. But they also know exactly what their offspring should do and are able to pass this information on. And their offspring, in turn, do the same to their own offspring. All of this information must therefore be stored in the original stem cell? If so, how is it stored?

So my two questions are:

Is the process of cell division and growth of an organism a kind of evolution in itself?

Is it possible that cells have some kind of intelligence and memory? If not, how else can this be explained?

The more I think about this the more incredible and magical it seems, and it seems to raise some very fundamental and important questions about the meaning and nature of life itself, and could point to a better understanding of how evolution works on a macro scale. What do we know about how the process works, and how can I find further reading on it?

I very much appreciate anyone taking the time to reply.

Thanks,
Matt

1. not evolution, but development. There isa large field of research on this topic.

2. Yes, cells have memory, this is managed through regulatory molecules.

Thank you for the reply.

Please could you explain the difference between cell development and evolution? I'm not sure I can understand what is different between a cell reproducing repeatedly and in the process mutating (to specialize?), and a collection of cells which do the same thing to change the shape of the overall organism. Is there a distinction? Or is the latter is just the former on a bigger scale?

Please could you tell me the name of this field of research and where I can learn more?

Thanks
Matt

Matt, I suspect you need to do a little reading on basic biology as I suspect you're laboring under some misconceptions. Some sources for you:

http://en.wikipedia.org/wiki/Cell_(biology)
http://en.wikipedia.org/wiki/Eukaryote
http://en.wikipedia.org/wiki/Sexual_reproduction
http://en.wikipedia.org/wiki/Cell_differentiation

Originally Posted by mattpryor

Thank you for the reply.

Please could you explain the difference between cell development and evolution? I'm not sure I can understand what is different between a cell reproducing repeatedly and in the process mutating (to specialize?), and a collection of cells which do the same thing to change the shape of the overall organism. Is there a distinction? Or is the latter is just the former on a bigger scale?

Please could you tell me the name of this field of research and where I can learn more?

Thanks
Matt

Cells in our body do not mutate to specialise. They all have the same DNA, they just express it differently based on their location and other information they receive- the process by which cells become liver cells, bone, muscle etc is called differentiation and does not result in changes to the DNA of the cell. Sometimes cells in our body mutate, but this is generally not productive and may result in destruction of the mutant cell or tumour formation. Except in very specific circumstances, mutation in our cells does not have a function. Most critically, these mutations are not inherited by our children and so cannot contribute to evolution. The mutation dies with the cell.

We each originate from the cell made from the fusion of two "half cells" (they have half a human genome each) produced by our parents- which we'll call reproductive cells for the moment. When a mutation happens in a reproductive cell such as a sperm or ovum, then there is the opportunity for inheritance. Since every cell in the new organism is a clone of that first fused cell, every cell in the new organism has the mutation. Mutations that are inherited may be functional, neutral or detrimental and undergo selection once they're expressed in the new organism.

Originally Posted by mattpryor

Thank you for the reply.

Please could you explain the difference between cell development and evolution? I'm not sure I can understand what is different between a cell reproducing repeatedly and in the process mutating (to specialize?), and a collection of cells which do the same thing to change the shape of the overall organism. Is there a distinction? Or is the latter is just the former on a bigger scale?

Please could you tell me the name of this field of research and where I can learn more?

Thanks
Matt

The field is Developmental Biology.

http://en.wikipedia.org/wiki/Developmental_biology

I understand that DNA, chromosomes and genes contain the information which tells a cell what type of cell to be, how long it should live for, how frequently it should reproduce and all that kind of thing.

You understood wrong.

It's the history of the cell + the environment + the genetic code + epigenetic information what tells a cell which cell it should be.