Enough about DNA...for now.

Switching gears, someone asked about me bones, having recently broken one of hers. We don't think of bones as being dynamic, we think of them as the key to our stability, holding up all our muscles. But bones are constantly being broken down by cells called osteoclasts (red cells in pic), and new layers are laid down by osteoblasts (green cells). In younger, healthy adults and children, this process takes place efficiently and on its own, so when you break a bone, the only thing to do is to minimize the movement of the bone such that it will set in alignment (think about putting a broken vase back together), and then let the osteoclasts and osteoblasts do their thing. 

In older adults, bisphosphonate, a common medication to treat osteoporosis, works on the bone cells. I have retro-fitted this old pic of mine to begin discussion. Essentially, bisphosphonate signals the osteoclasts to slow down what they do, while it signals the osteoblasts to increase their activity. Can anyone guess as to what the result of all this signalling leads to?