It's a typo - Larry meant um - micrometres - smallpox virus (and other pox
viruses) are big enough to be visible under light microscopy. - about 300nm
x 250nm.
GS
"Nicholas Landau" <njl2q at virginia.edu> wrote in message
news:3CB3BB33.4580793F at virginia.edu...
> Wait a minute... what coccus is 0.2 nm in diameter?!?!?!
>> Maybe a *really tiny* coccus could be 0.2 um in diameter, but 0.2 nm...?
>> No way Jose. I don't believe it. That has got to be off by three orders
of
> magnitude. Name the coccus.
>> Larry Farrell wrote:
>> > Again, as posted yesterday, some of the smallest cocci are 0.2 nm in
diameter and
> > smallpox virus is 0.2-0.3 nm x 0.25 nm.
> >
> > Nicholas Landau wrote:
> >
> > > The largest viruses are bigger than bacteria? Which virus? I never
heard
> > > that (but then, I never studied virology).
> > >
> > > --Nick
> > >
> > > Graham Shepherd wrote:
> > >
> > > > Smarty <smartman at comcast.net> wrote in message
> > > > news:3cab7bd6.18969629 at news.in.comcast.giganews.com...> > > > > Less than 500 milligrams
> > > > >
> > > >
> > > > An unusually unhelpful response.
> > > >
> > > > You can get an approximation by calculating the volume of the
organism from
> > > > typical dimensions (eg for E.coli assume it's a cylinder 1 micron
long with
> > > > a diameter of 0.5 micron) and assume that the density is the same as
water.
> > > > (It is greater, otherwise you couldn't spin them down - but it's
probably
> > > > not much greater. You could determine the density on a gradient if
it's
> > > > critical).
> > > >
> > > > A rough calculation indicates that the volume is about 0.2 cubic
microns.
> > > > That's 5,000,000,000 per cubic millimeter, or 5,000,000,000,000 per
cubic
> > > > cm. Assuming 1 gram per cubic cm, one bacterium weighs about 0.2
picogram.
> > > >
> > > > Viruses are much more variable in size than bacteria (the biggest
viruses
> > > > are bigger than the smallest bacteria). But you could do the same
> > > > calculation for a specific virus.
> > > >
> > > > GS
> >
> > --
> > Larry D. Farrell, Ph.D.
> > Professor of Microbiology
> > Idaho State University
>
