Questions on genetics: gene co-ordinate systems and gene interpretations

Speed

I am curious to know how cells in developing organisms can know which direction to grow in, how much tissue is required and in what proportion, and how to differentiate to the right cells.

If we just take the first issue, which is directional growth, I remember from my O-level biology classes that plants grow towards stimuli. How can this be the case for say a fetus inside a womb? It is more likely that some kind of co-ordinate system is encoded into genes.

Also, how do cells interpret genetic data? It might sound like a wierd question, but basically there must be some implicit assumptions which would determine that section X of the genes determine height, etc. Even if the gene has instructions within itself that section X determines height, some implicit assumption must still exist in that tells the reproducing cells that the instruction exists!

Without those implicit assumptions it would be like having a manual on how to build a car from iron ore, but not having any tools to do it with.

Monique

The answer is morphogen gradients. A cell expresses protein, the farther away another cell is, the less signal it will get.

Genetic data is expressed in proteins that do the function. There are feedback loops that tell the gene to either start expressing more of its protein, or less of its protein.

Speed

Interesting. Can you recommend any entry level books for someone who had my last biology lecture in Year 11? I am especially interested in the following fields:
1) Ontogeny;
2) Evolution;
3) Co-evolution of diseases, parasites and hosts;
4) Epidemiology;
5) Anything else involving genes...how they encode information, how the information is expressed, how organisms develop, how mutations arise, how genetic drift occurs, etc.

Something with the text pitched at about the level of your reply. It is ironic that I moved away from biological sciences in school, deeming them as "soft science", only to come full circle due to what is known as biomimetics in engineering.

Monique

A book that I really like is "Molecular Biology of the Cell" by Alberts et al. http://www.garlandscience.com/textbo...p?type=preview The book is very complete and discusses things from genes to development. It's written in a very readable way.

I can tell you more about the specific mechanics of development, they are very interesting.. but I'm a bit drained for this evening