June 28, 2012 | David F. Coppedge

Thank Your Cilia

Throughout your body, cilia (protrusions on cells, singular cilium) are monitoring the environment and sweeping your passages clean.

Live Science posted an article about cilia.  The simple-looking hairlike projections on cells are anything but simple.  “These hairs are tiny, but mighty,” the article began.  Your life depends on them.

Here are some wonders of cilia:

  • “A single cilium is made up of some 600 protein pieces—more than many other cellular structures.”
  • Primary cilia (non-motile) act like antennae, sensing the external environment.  Filled with proteins that amplify the signal, they act as a communications hub for the cell.
  • During development, motile cilia direct the liver on the right side of the body and the heart on the left.
  • Cilia sweep the airways clean of mucus by moving in concert in a wave-like motion.
  • Motile cilia direct the female egg to the uterus.  An extra-long cilium propels a sperm cell toward the egg.  (This is called a flagellum but does not work the same as the rotary flagellum found in bacteria.)
  • Cilia “circulate the fluid needed for proper brain function.
  • “More than a dozen rare but serious genetic disorders stem from cilia glitches.”

Reporter Amber Dance did not discuss how these organelles might have evolved.  Instead, she reported that scientists at Brandeis University are trying to imitate them.

This article was true to form: mentions of evolution are inversely proportional to the detail of complexity discussed.  Biochemist Michael Behe made cilia an example of irreducible complexity in his first book Darwin’s Black Box, and discussed them in more mind-boggling detail in his second book, The Edge of Evolution.  Make the design inference: (1) Cilia are composed of multiple interacting parts, all of which must be present for the cilium to work.  (2) Removal or damage to a single part destroys the cilium and results in serious disease to the organism.  Charlie, where are you?




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