Mighty Mitochondria Conduct Energy Exquisitely
October 7, 2011
None of us could live without mitochondria. These are the power centers ubiquitous in eukaryotic cells. They contain molecular machines in factories whose jobs are to generate and conduct electrical currents. The currents run turbines that packetize the energy in molecules of ATP, which are then used by most processes in the cell. New discoveries continue to fascinate scientists with how mitochondria work. Some scientists use their energy to find ways Darwinian evolution could build the machinery of life.
Your Rotary Engines Are Arranged in Factories
August 17, 2011
As if ATP synthase was not amazing enough, a team of scientists in Germany now tells us they are arranged in rows with other equipment to optimize performance. From electron micrographs of intact mitochondria, they were able to detect the rotary engines of ATP synthase and other parts of the respiratory chain. Their diagram in an open-source paper in PNAS looks for all the world like a factory.
Cell Chaperones Keep Proteins Properly Folded
August 2, 2011
Imagine linking together a chain of 300 plastic shapes, some with magnets at various places. Then let it go and see if you could get it to fold spontaneously into a teapot. This is the challenge that cells face every minute: folding long chains of amino acids (polypeptides) into molecular machines and structures for the cell’s numerous tasks required for life. DNA in the nucleus codes for these polypeptides. They are assembled in ribosomes in single-file order. How do they end up in complex folded shapes? Some polypeptides will spontaneously collapse into their native folds, like the magnetic chain in our analogy. Others, however, need help. Fortunately, the cell provides an army of assistants, called chaperones, to monitor, coax, and repair unfolded proteins, to achieve “proteostasis” – a stable, working set of proteins. That army is so well-organized and complex, scientists continue to try to figure out how it performs so well in the field.