Today, who are we? The University of Houston's
College of Engineering presents this series about
the machines that make our civilization run, and
the people whose ingenuity created them.
We all weigh the question,
"Who am I," now and then; but the place we hope to
find the answer shifts. I long ago despaired of
finding a usable answer in autobiographical data.
For a while, I thought it might be a matter of
self-perception. Then I read Oscar Wilde's wonderful quip,
"Only the shallow know themselves."
Now I'm reading a pamphlet by Maya Pines:
Inside the Cell. Maybe objective science
will tell me as much as the subjective stuff will.
Whatever else we might be, we certainly are great
gaggles of cells. So let's see what they have to
tell us:
Robert Hooke's book on
the compound microscope, Micrographia,
came out in 1665. In it, he sketched the
microstructure of a slice of cork. Then he wrote,
"I could ... plainly perceive it to be all
perforated and porous, much like a Honey-comb, but
... the pores of it were not regular." Of course he
was seeing the walls of dead cells in dead bark.
They'd once been filled with fluid, and alive.
Not until 1838 did a German botanist compare notes
with a zoologist. They realized the structures
they'd been studying in plants and in animals were
very similar, and they concluded that all living
things are made up of cells.
Twenty years later, it became clear that cells are
the home of disease as well as life. But cells
remained perplexing because they take on such a
dizzying variety of forms. And they execute so many
functions. Still, they all have certain basic
elements: They have a very thin outer membrane. It
holds a liquid called protoplasm. (That word came
from the theological term, protoplast. It once
referred to Adam as the first formed being.)
Also, with one exception, cells have a nucleus.
Pines calls it the cell's command center. The
exception is our red cells. They're formed in bone
marrow, they cannot reproduce, and they serve only
as carrying cases for hemoglobin. And hemoglobin,
in turn, transports oxygen throughout our bodies.
Pines presents a remarkable chart showing
the range of things that can be called cells. The
largest is a six-inch ostrich egg. A human egg is
only a 250th of an inch in diameter. Those red
cells are less than one millionth of an
inch.
But they all include nucleic acids, proteins,
lipids, carbohydrates, water, and salts. They all
include DNA. There's even some in our red cells.
Uncoil each long molecular helix of DNA in your
body, lay them end-to-end, and your DNA will reach
all the way to the sun and back.
Electron microscope pictures show human cells
girdled by an outer mess of microfilaments to help
them crawl. What frightful-looking creatures! Yet
there I am -- there you are: splatters
of organic matter, marvelously efficient, crammed
with complex apparatus -- mitochondria, ribosomes,
lysosomes -- more than we'll ever fully understand.
How right Oscar Wilde was! We would be shallow
indeed to think that we truly knew ourselves.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
M. Pines, Inside the Cell: The New Frontier
of Medical Science. U.S. Dept. of Health, Education,
and Welfare, 1978.
You'll find a huge amount of information on cells
and cell structure on the web. I won't even try to
list it all. For more on Hooke and his microscope,
see:
http://www.ucmp.berkeley.edu/history/hooke.html
and for more on cork, see:
http://www.jelinek.com/articles/virginbark-a1.htm
I am grateful to Lewis Wheeler, UH Mechanical
Engineering Dept., for suggesting the topic and for
his counsel.
The real me! Electron microscope picture of a human
cell beginning mitosis, or reproductive division.
(from Pine's pamphlet.)
The Engines of Our Ingenuity is
Copyright © 1988-2003 by John H.
Lienhard.
