October Update

Bought a standard poodle puppy.  Bringing him home October 5, so October will be full of housebreaking, and FUN.



Entries in mitochondria (3)


Genes Teach Us About Parkinson's Disease, Part 2

In my last post I was describing how, according to TheScientist

(2/1/11), genetic forms of Parkinson’s Disease can teach medical researchers possible causes for non-genetic forms.

         In certain genetic cases, a gene involved in releasing neurotransmitters is mutated so that it makes too much product.  When this happens, the excess product seems to result in fibrous bundles found in the brains of Parkinson’s sufferers.  But even with the normal gene, over-production can occur.  And such over-production seems to be connected to problems with mitochondria, the cell organelles that produce energy molecules from food.  So dysfunctional mitochondria may be associated with Parkinson’s disease.  Possible treatments might need to start with mitochondria.

         In certain other genetic cases, genes are mutated so that they produce to little or no product.  Interestingly, these genes also have to do with mitochondrial function.  Again, these genes point to possible treatments.

         To me, what is really intriguing about all this, aside from the possible paths to alleviation of the disease, is the connection with energy pathways in the neurons involved in Parkinson’s Disease.  When researchers finally are able to clarify the “mitochondrial connection,” what will they find?  Exactly how does energy production change dopamine production?  What else might be involved?  It will be fascinating to find out 


Pistons & Waterwheels: Is It God, or Is It Evolution? 

It’s hard to believe that evolution invented electrical transmission, tunnels, gates, and all manner of devices we humans take credit for.  Respiration, the method by which living cells harvest their energy from sugars, relies on some such inventions, specifically waterwheels and, as it now turns out, piston pumps,

         Inside our cells are micro-microscopic organs (“organelles”) that do the cells’ work.  One of these organelles, the mitochondrion, takes energy from sugar, and uses the energy to recharge the cell batteries that power cell work. 

         The batteries are molecules called ATP (adenosine triphosphate) when they are charged, and ADP (adensine diphosphate) when they need a charge.

         The charger is an enzyme that works like a waterwheel.  Instead of water, protons flow over a molecular dam, powering the waterwheel that packs a new charge into a phosphate molecule, and then attaches that molecule to ADP, to make ATP.

         In the last half of the 20th century, Paul Boyer and John Walker discovered how this waterwheel enzyme works.  They won the Nobel Prize in 1997 for this discovery.

         Now a Russian researcher, R.G. Efremov has discovered that another enzyme works like a piston pump, to push the protons behind the dam in the first place.

         It seems uncanny that these unbelievably tiny machines could have resulted from evolution.  And not from recent evolution, not in the plants and animals we know today, but in bacteria some 3 billion years ago.

         I've been thinking about the New Atheists and God:  The New Atheists believe in evolution, but not in God.  Yet frankly, if evolution can invent these fantastic atomic and molecular machines and coordinate their workings to maintain life, then evolution begins to sound a lot like God.  Hm-m-m.


Yet More about Cell Evolution

     In my last article I wrote about the endosymbiont theory, and I mentioned that certain organelles in eukaryotic (nucleated) cells, the chloroplasts and mitochondria, seem to be descendants of ancient bacteria. The chloroplasts are very similar to certain photosynthetic bacteria, and they perform photosynthesis in plant cells. The mitochondria are very similar to certain bacteria highly efficient at harvesting energy from various energy-rich molecules, and mitochondria perform the same function in plant and animal cells.

     Lots of mysteries remain. Did other organelles descend from ancient bacteria? If so, what is the connection? If not, how did such organelles evolve. Eukaryotic cells contain movable skeletal structures, flagella for swimming, packing and shipping structures, digestive organelles—plenty of evolutionary mysteries. But a major question is Where did the nucleus come from and how did it come to its present structure? According the the endosymbiont theory, somehow the nucleus, chloroplasts, and mitochondria came together into a permanent symbiotic relationship. We know of likely bacterial ancestors for the chloroplasts and mitochondria, but what about the nucleus?

      A nucleus in a present-day eukaryotic cell contains lots of, non-circular chromosomes—the number depends on the species. For instance, each fruit fly nucleus contains four pairs of chromosomes, each human nucleus contains twenty-three pairs. The chromosomes consist of DNA wrapped around histone proteins like thread wrapped around a spool. When genes on this DNA need to be copied into RNA, the DNA containing those genes unwinds.

      The nucleus itself is enclosed in a double membrane that keeps the nuclear contents separate from the cytoplasm of the rest of the cell. This double membrane is peppered with pores to allow certain molecules through. RNA copies of genes, for instance, pass through such pores, out of the nucleus and into the cytoplasm. There they conduct the business of producing cell proteins.

      The nucleus also contains apparatus and molecules for duplicating and dividing the chromosomes during cell-division, molecules for editing and perfecting copies of DNA and RNA, and much, much more. This complex organelle, the nucleus, like the chloroplasts and mitochondria, must have descended from some kind of prokaryotic cell. But is this ancestor still around? If so, we haven’t found it, though some biologists are searching hard.