let's begin our discussion by trying to
define what life actually is
we know that life is exceedingly rare in
our corner
of the universe but on earth life is
ubiquitous there are life forms that
live in the earth's crust down to many hundreds
of meters
bacteria their complex ecosystems in the
depths of the oceans
and in every ecosystem on earth from the depths of the oceans to
highest mountain tops and including the
Arctic regions
life is known to exist so
although not all biologists would agree on
a
common definition of what life is for
example some
would argue that viruses are not life,
there are some common features
that we can all agree on that define life
so living organisms are composed of cells
life on earth today is celluloid based
meaning the membrane separate
the internal cellular environment from the
external cellular environment
it might not always have been true the
earliest life forms may have been
replicated in molecules
but today life on Earth is cellularly based
and even viruses depend upon cells for
ther replication
they're dependent upon cells. Life forms are
complex
and you only need to look through a
microscope or simply
walk out in a mountain meadow to see
the complexity
that life exhibits and the key feature of
life is that it is very
ordered, life is ordered matter, ordered in
ways that
inorganic non-living materials simply aren't and we will be discussing that order
as we go through this semester we know
that life
organisms, living organisms, respond to
the environment
and the they do so in a variety of
ways
and that will be a part of our topics for the semester
we know that living organisms can grow
and they can reproduce growth doesn't
always mean
grow in size it can simply mean
that the number of cells might increase
and reproduction is absolutely
key to defining life because without
reproduction
life would not have evolved. When
we talk about reproduction in life forms
we talk about reproduction that
is heritable; whereas traits are heritable
from one generation to the next and that
is key
to evolution as we will see. So that's
growth and reproduction are
other characteristic of life forms. You
know that life forms
obtain energy and they use that energy
and
in fact part in this course will be
spent discussing the flow of energy
through the biosphere from the Sun
through
organisms and ecosystems, we'll spend
some time on that
we know the living organisms maintain an
internal balance
that is if you were to sample the
chemical composition
intracellularly, inside the cell, and
compare that to the
chemical composition outside the cell
they would be different in very
particular ways
in ways that, in fact, define
biochemistry and sells
and define life in essence
and of course living organisms will not
allow for evolutionary adaptation and
this is a key features
their reproduction allows the features
of life to change
overtime in response to environment or
other factors, so evolution
is a characteristic of life and if we
look at
three major domains of living forms on
Earth
this is what we see; we have the
bacteria
we have the Archaea and we have the Eukaryotes
to which we belong. The Eukaryotes have
the Protists in them, single celled Eukaryotes, the animals, the fungi
and the plants are all Eukaryotic
organisms and we'll discuss the features
of Eukaryotic
organisms shortly but right now Eukaryotic organisms
have some cellular compartments defined
in them
the nucleus for example or
the mitochondria. The Archaea
used to be thought of as bacteria
but are now recognized as a separate
domain of life
and the Archaea are single-celled organisms
with no major compartmentalization
like the Eukaryotes and then Bacteria
are
prokaryotic as well the Archaea and
bacteria are prokaryotes
and the prokaryotes
are single-celled organisms that do
not have internal partitions
in them and if we talk about kind of the
the organization of the
matter that is life we can
move through a hierarchy of
organization of matter
so organisms are made of matter and
matter
consists of atoms and those atoms are
assembled into molecules
and then those molecules in life forms
are found are
often found in macromolecular form that
is life
has very long large molecules that we
call macromolecules
they're large assembleges of much
simpler molecules much like building up
a complex structure from single LEGO
building blocks can construct legoland
for example
We know that there are organelles, an
organelle is the next
level of organization that we find in
Eukaryotes
for example here is images of a mitochondria
this is an electron micrograph and this
is a an artist's rendering of
a mitochondrion and
those organelles are then found at a higher level
in cellular life. Cells are then
organized into tissues in multicellular
organisms at least
and those tissues are further
organized into
organs so we see a sequential
buildup in the hierarchy
of the orderdness of matter in living organisms
and we can move on then from 
organs to
entire organ systems
like the nervous system that would be
found in a vertebrate
for example or an invertebrate for that matter
and those organ systems finally are
assembled into an organism like this
Canada Goose here. Moving further up the
hierarchy, moving from the organismal
level to the populational level
we then see the organisms are found in
populations
and those populations are often defined
species
or members of the same group of
organisms that can breed or produce fertile
offspring
species are often part of communities
which consist of a number of species
living together
and communities can be assembled then into ecosystems
which are much larger assembleages. For example this mountain ecosystem here
would have
a community that existed in the
mountain stream
or might exist on the
steep slopes, a community that
might exist on steep slopes in the
mountains
and there might be communities that exists at the
highest levels in these communities can
actually be different from each other
but together they would then form an
ecosystem
and finally all the ecosystems on Earth
together define
the biosphere
Now, before getting into the specific
topics that will
constitute the material of this course
let's talk about what the nature of
science is because this is science class
and we're going to use the methods of
science
to discuss genes & development
so that we can say that science really
is trying to understand the natural
world
through observations and through
reasonings
usually scientific questions start with
observations
and much of science therefore is
descriptive
but a large part of science moves beyond
description
to experiments, and experiments as we will
see
are used to test ideas
test hypotheses and to eventually build
up theories
and we came formalize this by saying
that science uses two types of reasoning
deductive reasoning and inductive
reasoning so let's talk about
inductive and deductive reasoning
deductive reasoning is using general
principles
to make specific predictions whereas
inductive reasoning
uses specific observations to develop
general conclusions
so we can draw that here, we can
have a skematic here which allows us
to define this so we moved from
in deductive reasoning we are moving
from general
down to specific whereas inductive
reasoning moves
from specific observations to more
general
theories so in this part of the
the right part of this skematic here we
might have theories
that would consist of a number of
hypotheses that have been
have a reason to be formulated
and then these hypotheses can be tested
with experiments
so this process of testing hypotheses
testing theories by experimentation is
deduction, we go from the general to
the specific
whereas moving from observations that
might
be obtained by experiments or might just
the observed
or  might arise from
observations in nature
scientists develop theories or
hypotheses to explain their observations
that are found
in either experiments or other
observations
so that constitutes induction, the left part of this skematic
is induction and we have moving from
specific observations
to more general ideas, theories
that is the main differences between
inductive reasoning and deduction
deductive reasoning in science and this
process
underlies all of Science, it characterizes
science as a
unique way of knowing about the world
given that theories like the appex of our
inductive
and deductive reasoning process in
science then it's worth considering
what exactly a scientific theory is
in the sciences a theory is a
particular framework used to describe
and understand the world around us
such a framework is only recognized as
a theory after a firm empirical basis
for its body of knowledge has been
established
this is done through such things as
extensive and long-term experimentation
and observation
Yikes what the heck does that mean?! Well what that means is our guest has
succinctly pointined out
is that a scientific theory is something
quite different than
the way that theory is used in the
everyday vernacular. The scientific theory as
opposed to "Oh I have a theory that
there are martians living on Mars"
a scientific theory is based on a
body of
interconnected concepts and in fact is a body of interconnected concepts
and these concepts which are encompassed
by a large umrella of a theory are supported
these concepts are supported by a
large fundament of
evidence empirical evidence usually
derived from experimentation
and deductive reasoning which tests
a number of hypotheses there are parts
of theories
now hypotheses can become theories
if they are thoroughly tested
but
usually hypotheses the word hypothesis
is used to
designate a smaller idea
about how something works whereas a
scientific theory
usually encompasses a large number of
concepts each of which
might be supported by the testing of
various hypotheses
and we can say that a theory
is an expression of an idea of which we
are most certainly
so we are fairly certain based on
on theoretical work and
by empirical work that mass warps
space  this comes out of Einstein's theory of relativity
and we are fairly certain of those ideas
they've been tested in a in a number of
ways now that's not to say
that theory could be
overthrown
that those theories could
be wrong and we're always open to that
in science
however for ideas to acquire the status
of a theory in science those ideas
have to have been tested and
supported by a large
by a large fundament  of evidence and
therefore
we refer to something as a
theory in science it's possible that it
could be wrong
and overthrown but usually it is
established and will remain
a part up or on body of knowledge in
science
so let's see how that would work
in a practical sense so
in this simple schematic let's take an
example of  inductive and deductive
reasoning
let's say we have an observation: the sky is
blue that could lead to question why is
the sky blue
again could then through a process of
deductive
reasoning and experimentation lead to
the development of a hypothesis
and the elimination competing hypotheses
where that hypothesis makes certain
predictions that can be further tested
by a variety of
empirical studies, a variety of experiments
they could then lead to decision whether
or not predictions
made by that hypothesis are confirmed
or not and if they are confirmed the
hypothesis would gain strength
and could become part of a theory now
let's examine
Darwin's theory as an example of inductine and deductive reasoning
