hi all dr. Clark here going to talk about
the properties of life gen bio lecture
number one okay so what I want to talk
about today is basically the definition
of biology and so when you look at the
definition of biology it is the study of
life well first in order to understand
biology in general well we got we have
to understand what makes something alive
so why would we call a pile of rocks or
a mountain not alive a bird
 like this hummingbird alive
or you know something in between like
this picture this virus viruses are
sometimes considered alive and sometimes
not considered alive so we're gonna
address these issues what makes
something alive and what how we define
whether something is alive so we're
going to look at the properties of life
okay so again biology is the study of
living things we know this that living
things are diverse about 1.5 million
species have been described to date
there's estimates you know of 8 million
species 13 million species a couple
hundred million species we know that we
have not categorized nearly even half
the number of species on the planet
and with huge numbers of bacteria
protozoans and fungi they probably
insects being left to describe now
things like mammals and birds were
pretty pretty excited when we discover
new mammal or bird but things like fish
plants insects we discovered them quite
often now if you're a fisheries
scientists you're pretty excited about
discovering a new fish but overall you
know things we know that life on this
planet is very very diverse so the one
thing that we can say and we'll get to
this point or kingdoms in a little bit
okay is that the organisms on the planet
can be arranged based on their
similarities and so we can start
grouping them and it's much like having
file folders for your different courses
or for your life and you can arrange
them and put all things that have
mammary glands in one group which we
would call mammals okay and everything
you know that has feathers in another
group which we would call birds but we
can do that even more broad we can say
everything that has this type of cell
that is going to go into the animal
kingdom and everything that is this type
of cell is going to go into the plant
kingdom and so this is a much broader
way to categorize different things and
it allows for scientists and just the
general public to know when someone says
an animal well what are we talking about
okay and we'll get to that point in
later lectures okay but the key thing
about like kingdoms where we're going to
talk about kind of being the most broad
although domains are the most broad
classification and we'll get to this I
promise but the one thing that we can
say about kingdoms is that they are very
different from each other if I tell you
this organism belongs to the animal
kingdom and this organism belongs to the
plant kingdom without even seeing the
organism you can just imagine that
there's going to be great differences
between those organisms we'll explore
that in much greater detail but the
first thing that we need to do is we
need to figure out what qualifies
something as being living versus
something being nonliving and I think
most people in their mind they say well
you know yeah it's easy to say that a
rock is not alive or you know this cell
phone is not alive okay and then for you
to hold up you know a dog and say but
this is alive but there are some other
things that make living versus nonliving
much more difficult conversation so we
should consider a few points and the
first point that we should consider is
complexity we often think that living
things are much more complex than
nonliving things but really we should
think do they have to be can you have
very simple
living things like can you just have a
cell that's considered alive
will approaches do they have to be able
to move when up if I tell you something
like oh yeah that's alive most of you
when you first hear that you can say
okay must be able to move but you know
you start thinking about that when was
the last time he saw a tree move but
trees are alive right now yes the branch
is swaying the wind and things like that
but so do some buildings so do some
science okay they move with you know the
wind okay so movement may not be that
important but maybe movement at a
different level
maybe movement of materials within the
system it's a movement of water
nutrients these kind of things might be
important and the final kind of piece
that I want you to consider point wise
is does this object that we're trying to
decide whether it's a living or
nonliving does it respond to stimuli
does it respond to outside forces such
as temperature precipitation pH okay
these kind of things wind touch these
kind of things now that doesn't
necessarily mean that it's alive as some
people would say well you know
a touchscreen on an iPad responds to
stimuli right it responds to you
touching it this is true it's been
programmed to do so and doesn't make it
live okay but it does make it that it
responds to stimuli so consider the
points it doesn't mean that these are
what makes something alive but these are
points that most people would consider
when they're basing whether something is
alive or not living but the key point to
all this is when we define something as
either being alive or not alive it
needs to be exclusive okay so the
properties have to be exclusive to all
living things so complexity movement
response to stimuli are not necessarily
a good point although those are points
that we often consider okay but when we
define something we need to define it
purely based on exclusive things
everything that's alive has these
features so let's go through those the
basic properties of life first property
they have to have cellular organization
and that doesn't mean that they have to
have multiple cells okay but they have
to be comprised of at least one cell
there's lots and lots of organisms on
this planet okay probably when it's all
said and done there's way more organisms
that only have one cell than organisms
that have multiple cells and so every
living
that we know of on this planet has at
least one cell now that does not mean
that through space exploration or more
time studying even our own planet that
we can't change this okay but right now
that's how we define or that's one of
the properties that we define life as is
they have at least one cell metabolism
so the organism itself has the ability
to process energy now processing energy
can be on a lot of different avenues
maybe it consumes things to get its
energy right these are called
heterotrophs they eat other material
okay and bring it in and then digest it
and use the energy or maybe it's an
organism that creates energy for itself
by capturing outside resources maybe
sunlight or chemicals now they're not
consuming material like they're not
consuming other organisms okay they're
consuming energy photons chemicals those
kind of things
and those guys are called both
autotrophs and those are be plants and
and some types of bacteria in you know
some photosynthetic protozoans and
things like that
okay they have the capability of
bringing in outside sources either
through photosynthesis or chemosynthesis
something along those lines and I don't
want to say creating energy but
utilizing that energy from the outside
source to make chemical energy or what
we'll call bond energy and we'll get to
this when we start talking about
chemistry okay homeostasis and this is a
property of which things maintain a
stable internal environment which allows
them to optimize metabolism and other
processes reproduction digestion all
kinds of things okay now often when
people talk about homeostasis and
maybe you've been taught in the past
ideas of homeostasis we often think
about it from a human mindset okay
because we think about lots of things
from a human mindset because we are
humans but we often think about
homeostasis from just humans so when I
say maintain a stable internal
environment you would say oh yeah like
you know the temperature of our body
is 98.6 degrees okay yes that is an
example of homeostasis
but remember maintaining a stable
internal environment does not mean that
you have to have a temperature profile
that is rigid
you know we deviate much around that
98.6 okay couple degrees below and we
could be in really bad shape a few
degrees above we could be in really bad
shape so we have a very very small
profile temperature profile that we can
maintain
versus some other organisms you
know let's look at something like a
snake okay if a snake was in the
environment that I'm sitting in right
now we're about 70 degrees Fahrenheit
okay the body temperature of that snake is
70 degrees Fahrenheit if I go over to my
thermostat and I turn it up to 80
degrees okay the body of that snake is
going to raise to 80 degrees if I you
know put some air conditioning on or it
gets cold outside and it drops down to
50 okay the body temperature the snakes
going to be 50 degrees C their
temperature profile is much wider and so
they can move throughout that
temperature profile a lot more now
they're going to be optimizing
conditions inside by you know moving
energy from one area to the next K by
cooling themselves or by controlling how
much movement they do and behaviorally
optimizing their internal conditions
okay to stabilize their temperature
within that range just like we do okay
if you get too hot you're gonna sweat
too cold you're gonna shiver okay these
things are not controlled by you
these are innate or genetically
controlled things all snakes do the
same thing other reptiles also okay but
what I'm getting trying to get across
here is that homeostasis does not mean
stable in the sense of a stagnant
temperature stable means it's within
your range and lots of organisms have
all kinds of different ranges all kind
of different ranges when it comes to
temperature when it comes to pH when it
comes to salinity when it comes to
humidity or how much water they have
there's different ranges in which they
become stable okay so homeostasis don't
think of it as one single temperature
but rather staying within your optimal
range all right organisms have the
capability if you're alive to grow and
reproduce
okay these are key aspects okay so the
capacity for growth and reproduction
everything that's alive has to be able
to do that and that's pretty
self-explanatory and then five is you
must be able to inherit genetic
information you must be able to pass
information from one organism to the
next that doesn't mean that information
has to be different so that can be
genetic information that's passing from
one organism to the next and it can be
identical genetic information ie cloning
so there's lots of bacteria and archaea
out there that just clone themselves and
there's other organisms too some plants
and you know some other organisms out
there that that clone themselves readily
and lots of animals can do it too okay
but the genetic information is still
passed whether it's changed or not okay
it's being passed from one organism to
another organism so parent to offspring
now based on those five things our virus
is alive
that's a question that often you get and
and you'll hear this okay the you know
it's fall right now so well it doesn't
matter if it's fall or spring I mean in
Wyoming whenever you're close to outside
of really the summer okay you have lots
of fluctuations in temperature and with
fluctuations in temperature our bodies
fluctuate and we get more exposure to
viruses and bacteria and things like
that so people will get sick okay and
you know the cold virus is always a
concern for a lot of people and so maybe
you'll get the you know a shot okay like
the flu shot and so you go to a clinic
or whatever and get a flu shot and a lot
of times they will tell you we're going
to inject the dead virus into you they
use that term dead virus so that would
assume or you would assume as you know a
layperson or somebody that is studying
biology now okay that the virus was once
alive so our virus is alive I get this
question a lot well we can first start
looking at their life cycle so this is
what we call a bacteriophage virus okay
and so you can see here that the
bacteriophage is coming in
this is a bacteria and this is the virus
comes in and it has DNA itself and it
injects its DNA into the bacteria so the
viral DNA is coming into the bacteria
okay and then once the DNA leaves the
virus the virus can then disassociate or
it can just stay on there okay but the
DNA goes in it encounters the DNA of the
bacteria it gets incorporated with the
DNA of bacteria will will approach this
more in more detail but for right now
that's you know that's the knowledge
that you need to know it gets
incorporated into the chromosome or DNA
of the bacteria in doing so when that
bacteria multiplies it multiplies the
viral DNA also and so the virus is being
replicated inside the bacteria when that
happens the building blocks for the
virus are being made based on the DNA
and you get new bacteriophages that you
know occur are built okay inside this
bacteria and then eventually that
bacteria is lysed
or you know something occurs so the
viruses can escape out of the bacteria
okay so based on that now you know the
lifecycle of a typical virus are they alive
so let's look at the components of
viruses
first of all virus have no resemblance
to a cell and they lack any real
mechanisms to to make proteins okay now
they could have a protein associated
with them often they steal that from the
host cell but they do have DNA or RNA so
they have an information carrying
molecule okay remember one of the five
things um well really two of the five
things that you have to have is you have
to be able to inherit DNA or RNA some
genetic material and you have to be able
to pass it on it through reproduction
okay so they do have that capability you
just saw their life cycle they inject
their own DNA and they replicate
themselves but they have no mechanisms
for synthesizing proteins
the other pieces they contain only parts
that are needed to invade or control a
host so they can't reproduce on their
own so if let's say I had in this little
vial
I had the cold virus a war HIV or you
know there's lots of different types of
viruses but let's say I had a sample of
it and that's all it was in there just
the virus maybe some liquid you know so
they can exist in there okay but there
are no bacteria okay there are no
potential host cells in there well if I
left it sit there for you determine the
time it doesn't really make a difference
okay
10-15 years the same number of virus
would be today as from 10 years from now
okay as long as there are no you know
outside forces being you know put in
there or anything like that it stays the
same they cannot reproduce without a
host okay so they can't reproduce alone
so here are some key points for viruses
they can't synthesize proteins and they
can't reproduce alone now that would in
most people's eyes violate them from
being alive okay so without producing
proteins they can't really have a
metabolism
okay homeostasis is difficult okay they
don't have cells so they just violated a
lot of the components of being alive now
if I told you though there's a
professor and viral biologist named Eckard Wimmer who has taken the genetic
code for a virus
reproduced it and got the virus to
reproduce all by itself so it doesn't
need a host anymore so he recreated a
virus by just looking at the DNA code
doesn't need a host cell and he did it
in like a test tube so based on that
knowledge our virus is alive now that
can't reproduce by themselves might be
avoided well it depends on who you talk
to
it depends on the you know the
biologists you talk to majority of
biologists consider viruses not to be
living but rather they are either active
or inactive but there are some
biologists out there some scientists out
there that believe as we progress that
viruses if they can reproduce on their
own they should be considered alive okay
we haven't found one in nature that can
reproduce on its own but we've been able
to synthesize one in a lab that can
reproduce on their own so the odds that
you know they could reproduce on their
own you know it's pretty good that
there's maybe a virus out there that we
haven't discovered yet
that doesn't need a host okay now I'm
not saying there is but the odds are
fairly good okay here's a YouTube video
on Eckard Wimmer he gives a very good
interview okay where he talks about his
research in the history of his research
and the pitfalls and kind of the
problems with viral research and what
can happen when you design viruses from
just looking at the
genetic codes so i suggest that you watch
that clip and and get an idea of a viral
component okay the other thing is you
know when we look at human DNA we're
about 8% of viral DNA so when you look
at the entire human genome about 8% of
our DNA is virus DNA now that has and
and this is kind of a new newish field
okay a newish field that people
are starting to examine well what does
it mean to have that 8% viral DNA are
these is that viral DNA remnants of a
time where we might have had that virus
and it got incorporated into our genome
and now we're carrying that virus
viruses genome with us what's going on
here
you know so from an evolutionary point
of view having viral DNA suggests that
and we're not the only organism all
organisms have viral DNA okay it
suggests that viruses have been around
for hundreds of millions of years and
they might be driving some evolutionary
components more than we give them credit
for given that we have their DNA within
our body okay now a couple books in a
video if you're interested guy Carl
Zimmer is an excellent author when it
comes to scientific and more geared
towards the public he wrote a book
called the planet of viruses okay I
highly suggest that you read this book
I'll put a link below okay and then
an excellent book by Jared Diamond which
he wrote Guns Germs and Steel about how
North America was taken over and really
how the world was taken over by these
three things if you don't want to read
the book National Geographic in my
opinion did an excellent job recreating
the book okay and and if you've never
watched this you know I put a link so
you can purchase it but I think you can
probably you know watch it maybe on
Netflix or Amazon or possibly even
YouTube in pieces maybe get through the
entire series both things both pieces of
the literature and media are excellent
if you want to learn more about viruses
okay all right so when we look at that
piece and now you know I'm going to
approach it from viruses are not alive
okay because they do violate you know a
few of the five things that we would
consider you know things must have to be
alive okay but
when we consider something alive it's
not just enough to consider it alive
we also need to consider well how is it
organized okay what level of
organization can we move through so
there are lots of ways at which we can
organize life and there's lots of ways
which life interacts at many different
levels and so often we call this the
hierarchy of organization of life and
and as we move from very simplistic
pieces which we would consider
simplistic as a biologist and we move
our way up life gets more and more
complex so if we look at cells cells are
less complex than say the organism that
you know would have those cells so maybe
you have you know muscle cells and fat
cells and nerve cells okay in the
organism but the organism itself is also
less complex than say the populations of
all of one species and so this is what
I'm talking about when we talk about
hierarchy levels and we're going from
something very simplistic to something
very complex and that is exactly how
this course is situated and designed
we're going to start very simple and
we're gonna build on these simple ideas
and simple concepts till we get to
something that is very very complex but
is built from all these smaller building
blocks okay so we can start at a
cellular level where we're talking about
atoms molecules and macromolecules and
organelles and cells okay so a lot of
this is beginning okay what we're gonna
talk about chemistry and macromolecules
and the cells and then we'll move to
organisms where we might talk about
tissues or organs or you know an organ
system
okay and then an organism okay like this
brand canadensis or the Canada Goose
okay and then we can go from well if we
take all those Canada geese and we have
them in a given region we call that a
population okay and then you can look at
all the populations of Canada geese on
the planet that's the species okay and
then you might look at that versus say
sandhill cranes okay and then you know
these two organisms occupy the same
place at the same time so they're part
of the community and so depending on
what aspect we're looking at we might be
looking at you know atoms and as we
progress we're going to start looking at
ecology or community ecology or
population ecology okay and that's
really how the you know course is
designed and the process by which we're
going to move through the course okay so back
to you know kingdoms okay so six
kingdoms archaea bacteria those guys are
what we call prokaryotic kingdoms they
do not have a true nuclei
okay they still have DNA okay or RNA in
some cases but they do not have a true
nuclei okay and they have no organelles
we'll come back to this when we start
talking about cells then we have
Protista fungi Plantae and Animalia okay
those are what we call eukaryotic
kingdoms and those are grouped because
they all have a true nucleus okay and
often have some type of organelle
associated with them at least one if not
a lot more than one
yeah and so we're gonna approach this
will talk lots of different processes
where whether I talk about reproduction
or whether I talk about how energy is
obtained I'll talk about it from a
prokaryotic so archaea and bacteria
point of view and a eukaryotic Protista
Fungi Plantae and Animalia point of view
okay all right with that being said okay
join me for the next session and we'll
start diving in to a little bit more on
how scientists think and how scientists
do biology okay peace out
have a good one
