Download Bacteria are the smallest and simplest cells "You know when people

Bacteria are the smallest and simplest cells
"You know when people talk about recycling and
biodegradable? Well, soil bacterium here does the
biodegrading! He takes all that organic material that
falls on the ground and breaks it down into small
enough pieces for plants to take in through their
roots. He does a wonderful job, too. It's hard to see
the bacteria, but without him, you wouldn't be able to
see all those plants everywhere.
The bacteria has a cell
wall all around him for
protection; kind of like a
suit of armor. Just
inside of that, he has a
membrane that keeps
his insides inside and his
outsides outside.
And thrown pretty much anywhere inside is his DNA,
protein-making factories, energy making devices, his
digestive system, and everything else. It has pretty
much all the same sorts of stuff that plant and animal
cells have, only he just throws it wherever it will fit.
He's not as organized as plant and animal cells. You
probably know people like this bacteria.
the E. coli!
It does the same sort of thing that soil bacteria
does, only Instead lives in animals' intestines instead
of the ground. It probably knows some of the E.coli
that are living in you right now! It also knows that
bad branch of the E.coli family that cause people to
get sick. After your stomach has had a chance to
grind your latest meal, the food continues down to
your intestines. That's where it helps you out. He
takes some of the food your body can't digest and he
digests it for you. He breaks down some of the big
molecules of food into small molecules that are small
enough for you to absorb. This works to both its and
your advantage; you feed it and it helps you get more
out of a meal!
Bacillus anthracis spores
Photo: Dept. of Defense
What causes anthrax?
Anthrax is caused by a bacterium (not a virus). More
specifically, it's a rod-shaped bacterium that stains
purple in a laboratory test.
Where are the bacteria found?
The bacteria live in and on infected animals, and in
the soil. The bacteria can't survive long in the
environment when they're in a growth stage. But
when they form spores -- which they do when the
environment changes (for example, when they run out
of food) -- they can live in the soil for decades.
How do people get infected?
There are three forms of anthrax: inhalation (where
the bacteria lodge deep in the lungs), cutaneous
(skin), and intestinal. By far the most common form is
cutaneous (about 95 percent of cases).
THE WORLD OF ANIMALS IS REPRESENTED BY A FLY, A WORM, AMOUSE AND
HOMO SAPIENS
Figure 1-34/35: Drosophila melanogaster &Caenorhabditis elegans. Molecular genetic
studies on this small fly have provided a key to the understanding of how all animals develop.
This small nematode worm lives in the soil. Its development, from the fertilized egg cell to
the 959 cells of the adult body, has been traced in extraordinary detail, and a great deal is
known about the underlying genetic mechanisms. Most individuals are hermaphrodites,
producing both eggs and sperm.
Figure 1-36: Different living species share the same molecular
mechanisms.
The human baby and the mouse shown here have similar white
patches on their foreheads because they both have defects in the
same gene (called kit), required for the development and
maintenance of pigment cells. (Courtesy of R.A. Fleischman, from
Proc. Natl. Acad. Sci. USA 88:10885-10889, 1991
Cells in the same multicellular organism can be totally
different. Yet all differentiated cell types are
generated during embryonic development from a
single fertilizied egg cell. We share the same
molecular mechanisms!
Systems Biology
Over the last few years, there’s been an
explosion of information in biology. The mapping
of the human genome gave biologists
unprecedented detail about some 30,000 to
40,000 genes. Efforts are also under way to
identify the thousands—and potentially
millions—of proteins encoded by those genes.
Researchers are now pursuing the next logical
step in integrating all this data: systems biology.
The goal is to understand not just the functions
of individual genes, proteins and smaller
molecules like hormones, but to learn how all of
these molecules interact within, say, a cell.
Biologists hope to then use this information to
generate more accurate computer models that
physiology and the underlying mechanisms of
disease. The biggest payoff: faster development
of more-effective drugs. “This is really opening
up a whole new world, a new way of doing
things,” says Aram Adourian, director of
advanced technologies at Beyond Genomics, a
systems biology startup in Waltham, MA.
The Big Picture
Companies exploiting systems biology
Institute/Company
Location
Focus
Institute for Systems
Biology
Seattle,
WA
Understand
human physiology
and disease
Beyond Genomics
Waltham,
MA
Lilly Center for
Systems Biology
Singapore
SurroMed
Mountain
View, CA
Alliance for Cellular
Signaling
Dallas, TX
Identify new drug
targets
Develop new
drugs
Mine multiple
biological data for
new drug targets
Map all
interactions
between proteins
in a cell