Are Viruses Alive?


Uploaded by MontanaEPSCoR on 18.01.2011

Transcript:
Ah, the famous question: Are viruses alive?
Well, it depends how you look at what life is.
So, why is that a hard question to answer
It's really a hard question to answer because no one
has a definition
of what life is yet.
We really don't know.
And you ask what's a challenge in science
it's closing in on really understanding what life is.
I think we're getting closer and closer.
So what we have-- we actually have a list of characteristics of
properties of life.
but all of those characteristics are not exclusive of life meaning there's something we all view as
something that is not living
that has that characteristic. Let me give you an example,
I know we're drifting some here, but,
a lot of people say, ok,
life is defined by replication.
It reproduces more of itself
Well, crystals do that
and crystal growth
replicates on a template just like life replicates on a template.
Are crystals alive?
I think most of us would say no.
but that's commonly used as a property for life
so there's a series of characteristics of life
and viruses actually meet almost all of those characteristics, except one,
and that is
all life
that we know about
encodes for a certain set of, a certain set of genes can code for
a set of proteins
that make more proteins.
These are ribosomal proteins
And so far no virus has been discovered that does that
But all life does that.
Now, I'm not convinced that we won't find that there's been a gray blurring between
cells and cellular life
and viruses
What's caused that blur?
Well, what's caused it in recent years is --we think of
viruses as small
cells as big
viruses as always being a parasite
of the cells in which they
replicate
but now we've discovered viruses that are actually bigger than cells
both physically and in their genetic content, meaning they have more genes
than cells have genes
and they're physically bigger
so I think we're
seeing this
continuous spectrum
between cellular life
and viruses
and where a virus becomes
a cell essentially is the question.
We'll wait and see
I think looking towards the future
if you ask. . . Well, let me put it this way:
there's kind of
a drive in science right now
to make synthetic life
De novo
started from test tubes essentially
creating life
And if you can do that, you obviously have some understanding of what life is
and i think the first examples of doing that aren't going to be with cellular life but we're going to create viruses which are
very lifelike
totally de novo... in the near future
and I think this will be very exciting because this will give us a lot of insights
into
not only how life evolved on this planet
and where it's going in evolution
but what life itself is.
So, stay tuned. . .