SOMETHING NEW ABOUT CALCIUM

Many, many years ago.

Linda is disgruntled, Carolyn is content, and Eben is - well - engaged in an all-too-human activity.



I was pleased to encounter this article in Google alerts.  It not only contains some encouraging results, but it also gives me a chance to show of some of my (superficial) grasp of biology.

There are two kinds of cells: eukaryotic and prokaryotic.  (Yes, you knew that already.  Bear with me.)  Our friends the bacteria are composed of prokaryotic cells, whereas all we multi-celled organisms use the eukaryotic kind.  Eukaryotic cells are big and complicated.  In addition to a lot of goo called cytoplasm, they contain membrane-bound compartments known as organelles.  The nucleus is an organelle.  So are mitochondria. 

Mitochondria are the power-plants of cellular life, in that they convert “fuel” (food) into energy.  They do this by manufacturing something called adenosine triphosphate (ATP).  The mission in life of ATP seems to be to wander about slapping energy-rich phosphate groups on things that need to go.  Without ATP, we croak.

Incidentally, an interesting hypothesis holds that mitochondria once may have existed as independent  cells that were engulfed and enslaved by bigger cells.  Evidence for this includes the fact that mitochondria have their own DNA.  As the bigger cell protects the mitochondria, I guess this is a case of symbiosis.

Anyway, mitochondria communicate with the rest of the cell by means of a “messenger”; in this case, calcium ions (Ca2+).  Thus, if the cell needs more energy it releases Ca2+ ions from another organelle, the endoplasmic reticulum (ER).  Please do not ask me what THAT thing does.

So, it appears that some stuff found in sea sponges in effect blocks holes in the ER out of which the calcium ions are emitted.  Deprived of Ca2+ stimulus, the cell goes into “bioenergetics crises”.  In the case of normal cells, the crises can be mitigated by a process called autophagy, which translates into “self-eating” – and the cell can survive.  However, for some (not explained) reason – possibly because they divide so frequently – cancer cells die.  Or so say mouse-model studies, as well as studies using human cell lines.  Potential for useful cancer therapies are evident,

Here is the article:  http://www.cancer.gov/news-events/cancer-currents-blog/2016/blocking-calcium?cid=eb_govdel

By the way, I wish someone with some formal training in biology would explain to me what happens to the mitochondria when a eukaryotic cell undergoes mitosis.