so those are carbohydrates mostly energy
type of functions to them a little bit
of identification purposes they have
specific structures to them and they can
be either single molecules or built up
into much longer chains of molecules
our next biological molecule are lipids
and these are always hard to talk about
because they are super diverse if you
want to talk about a big umbrella of
many different kinds of molecules a
lipid you can't get much more diverse
than that one of the one things that
kind of unites all the lipids that we're
going to talk about is their insoluble
in water so they essentially are going
to not be able to dissolve in water very
well which would make them hydrophobic
now all the lipids that we're going to
be talking about are things like fats
which are the more solid type of lipid
oils which are the more liquidy type of
lipids and steroids which are a special
kind of lipid that we'll talk a little
bit more about later now one of the
most importance kinds of liquid lipids
that we'll talk about our fatty acids so
these are all fatty acids here the
reason that they are called acid is
because of this part right here this is
a carboxyl group and what happens in a
carboxyl group
when this molecule is put into water is
this H tends to leave as a proton and
when an H leaves and water as a proton
that's kind of the definition of an acid
so these are acids but what's more
important about what's more important
about fatty acids is this long tail over
here so this long tail can have
different lengths it could be 12 carbons
long it could be 15 carbons long could
be eight carbons long so there's
different lengths
of these carbons and also very important
is how these carbons interact with each
other and how these carbons interact
with hydrogen so if all of these carbons
within the long tail of a fatty acid are
bound by single covalent bonds to
hydrogen as much as they can be this is
what's known as a saturated fatty acid
so if there are single bonds all
throughout the carbons of this long tail
then this fatty acid is what's known as
a saturated fatty acid and what that
basically means is it's a very straight
molecule so all of those carbons in the
long tail have these single bonds to
them and they get very straight in their
structure and because they're so
straight
many of these fatty acids if they're
next to each other can stack very nicely
on top of each other and because they
can stack so nicely close to each
other on top of each other they create a
solid at room temperature
so think like butter or lard these are
our saturated fatty acids because that
long tail there is single bound
carbon to carbon and carbon to hydrogen
and because it is all single bound
single covalent bond it can create a
nice straight tail now you can also be
unsaturated so the unsaturated means
that one of your carbons if you are mono
unsaturated mono meaning one or multiple
carbons if you are poly unsaturated are
not completely single bound to either
carbon or hydrogen they are double
bonded so they are double bonded to
another carbon within that chain so here
we see the double bond here we see
multiple double
because this is a poly unsaturated fatty
acid so what does that do double bonds
when a carbon double bonds like this it
actually kinks or bends that chain so
when that double bond happens you get
this kind of bend to the chain and then
if you try and make these guys stack
next to each other with all their little
bends and pushy out bits they're not able
to stack so nicely as our saturated fats
are able stacked on each other so
they're all bent and like this and that
means if they can't get together close
enough then they are a liquid at room
temperature so these are your oils here
your monounsaturated and your
polyunsaturated fatty acids are gonna be
your oils at room temperature now fatty
acids are very important will be
discussing fatty acids when we're
talking about metabolism so your body
breaks down fatty acids in order to get
energy but fatty acids just by
themselves are not the most common kind
of lipid that you're gonna find in the
body
the most common kind of lipid you'll
find in the body is three fatty acids
bound together by a molecule of excuse
me glycerol creating a tri glycer IDE
so triglycerides are very important for
energy storage and for breaking down and
using as energy these are the most
common type of lipid or fat in the human
body so something like 90% of the lipids
inside of your body are bound together
in these big molecules called
triglycerides a triglyceride is just
going to be three of these fatty acids
here bound to a single molecule of
glycerol so glycerol is just this tiny
chain of carbons with some OH groups
on them the Oh groups are going to
help
bind the the acid carboxyl groups here
and we get those fatty acids bound to
this little backbone here of glycerol so
most of the fat inside of your body is
going to be in this triglyceride type of
molecule now we also have a range of
different other kinds of lipid like
molecules these are going to come up
much less throughout the semester but
they do have some very important types
of roles so we're going to take a quick
look at them one of them is these eiconosanoids and eiconosanoids  are very
important messengers so there are
messengers and the messengers and
regulators within the body basically
they are going to control a lot of
functions like inflammation they write
that one down and what they are are
modified their modified fatty acids it's
a long word so we take a look at this
molecule here it almost looks like a
fatty acid we've got the carboxyl group
here that one where the H kind of splits
off and is an acid and then
this guy if it was just a long straight
carbon chain would be a pretty normal
poly unsaturated fatty acid but in
creating these molecules there is this
extra covalent bond that comes here
between these carbons to create this
little Pentagon shape here at this end
of the molecule in the middle of the
molecule and that creates a kind of eiconosanoid which then turns this more into a
messenger versus a kind of energy
molecule
now steroids are going to be very
important molecule steroids are
important hormones inside the body so
their long-distance messengers so these
are more local messengers over here and
these are long-distance messengers
I'll get better at this kind of thing is
this semester goes on so what is a steroid
a steroid basically is going to have
this structure right here these three
hexagons and this Pentagon so though
that structure will kind of always
remain regardless of what steroid we're
talking about and what's attached to
those four different ring-like
structures is what changes that steroid
from say cortisol to testosterone to
estrogen to all the other many kinds of
steroids that the body has so we can see
that when this is attached to that ring
structure its cortisol when other things
are attached its estrogen or
testosterone or something else
most of the steroids of your body are
first created from cholesterol so
cholesterol has this structure right
here a steroid molecule and these pieces
will get chopped off new pieces will get
added on and you'll create the steroids
of your body starting with cholesterol
here now the last kind of special lipid
that we're going to discuss is the
phospholipid and we actually have
already discussed it a little bit so
phospholipids are those amphiphilic
molecules in which they are a modified
triglyceride so we've got that glycerol
right that little backbone we've got two
fatty acids attached to it and instead
of a third fatty acid we're going to
have this phosphate group attached right
here so this phosphate group has the
polar aspect to it which is going to
make this the hydrophilic part of the
molecule and then these are the
hydrophobic parts of the molecule
and so we get that amphiphilic nature
and what these guys are able to do are
create those barriers so they can create
a double barrier with liquid on the
inside so there would be h2o here and
h2o out here or they can create the
single layer types of spheres in which
there's just hydrophobic fatty acid
tails on the inside and the outside just
kind of has those hydrophilic
phosphate groups so that the they can
move around inside of the watery
environment inside or outside of itself
so these phospholipids very important in
creating those barriers to create
compartments within cells and
compartments of cells for an entire body
so a lot of different kinds of
characteristics and functions here of
lipids they are insoluble in water
they're nonpolar usually they're very
energy dense so the phospholipids
important cell membranes as we've talked
about and compartmentalization our
triglycerides one glycerol backbone with
three fatty acids attached to it
important sources of energy they're in
insulators so they kind of are able to
keep our heat in and the cold out and
there are also protectors of vital
organs so you're going to find fat
layers around things like the kidneys
and the liver and the heart that kind of
just protects it from the shocks of the
everyday life yecionosanoids
these are our local messengers so they
take information around a very small
centralized localized particular area
that they are produced in and then
cholesterol and our steroid  type
hormones these guys are going to be
important in long distance messaging
and also
they also are found in these cell
membranes of the body they usually
within cell membranes are going to be
kind of hydrophobic plugs will say h2o
phobic plugs so they kind of stop water
from leaking through the amphiphilic
phospholipids of the membrane and we're
going to discuss in the next lecture
we're going to begin to discuss the
dynamics of a membrane so how things get
across why things get across things like
that and we'll discuss a lot more how
water interacts with those membranes
then so we've talked about kind of how
carbohydrates we've talked about our
lipids here the next important molecule
are proteins so proteins are large
molecules that are made up of tiny
pieces those tiny pieces are called
amino acids there are 20 amino acids and
they each have a different R group here
so every amino acid that you look at is
going to have an amino group which is
this nitrogen part it's gonna have our
carboxyl group just like the fatty acids
we'll have a hydrogen they'll have this
central carbon that everything is
attached to and then I'll have a side
chain this R type of structure and this
R here can be many different things so
if it's tyrosine this is the R if it is
glutamine this is the are there are
hydrophobic R's there are hydrophilic
R's there are polar R's there are
nonpolar ours there's a lot of different
kind of residual groups which is what
the R stands for here that are attached
to that central carbon so 20 if
differnt R's that can be attached to that
central part now it's these R groups
that kind of give the amino acid its
particular interacting type of
capabilities so if it is polar or if
it's nonpolar if it's hydrophobic or
feel like if it can combine with other
things through hydrogen bonding or
things like that that mostly has to do
with the R group here these kind of the
amino group and the carboxyl group are
mostly important in connecting these
amino acids together to create a larger
molecule so the carboxyl group and the
amino group are going to utilize the OH
of the carboxyl and the H of the amino
group kick that out and create a new
covalent bond between the carboxyl group
and the amino group of two amino acids
so this is how two amino acids combine
this is how two amino acids form the
larger proteins that we are actually
interested in so these amino acids
combine to form these larger proteins
the proteins are the main functional
units of our cells and what I mean by
that is if there's anything that sort of
happens inside the cell if there's a job
that needs to be done if there is
something that needs to be performed
it's usually going to be a protein
that's going to be doing that job so
proteins have a number of different kind
of levels to their structure the first
level of structure of a protein is its
primary level or its primary sequence so
the primary level is just which amino
acid is bound to which other amino acid
to create the long chain that is the
protein so that's the first kind of
level of structure to these proteins and
what we're going to find especially
proteins and so it's been true
for carbohydrates and lipids but
especially for proteins the structure
the kind of look of it is incredibly
important in the function of it so how
it looks
equals what it does so the primary level
of its structure is just which amino
acid is bound to which amino acid to
create this chain of proteins and after
you've created that chain of proteins
imagine like a long beaded chain in
front of you you're gonna create some
loops and some switchbacks in that chain
you're gonna create some curly Q helixes
 things like that this is what's
known as the secondary structure of
protein so the secondary structure is
going to be created by hydrogen bonds
between these loops and chains inside of
that primary structure so if you
remember hydrogen bonds is between
hydrogen and some other negatively
charged part of a molecule so these
hydrogen bonds are going to be forming
to create these little kind of curly Q
helixes these are known as alpha
helixes or they're going to have a kind
of sheet like bend or a kind of switch
back here so what you would have on this
guy that's not actually shown is the
structure and it connects like that so
the primary structure goes along then it
loops back and creates this other kind
of wrinkled type of sheet here and these
are known as beta sheets so these beta
sheets connect by hydrogen bonds these
little alpha helixes also connect by
hydrogen bonds between the molecules
within the protein so we get this kind
of secondary structure so the primary
structure is just a bunch of beads and a
chain
secondary structure you create some
loops or some switchbacks on that chain
and the tertiary structure is all of
those loops and switchbacks kind of
combine together to create a big
three-dimensional shape so this is
what's known as the tertiary structure
of proteins the tertiary structure is
going to give it its actual shape the
actual shape that it uses to kind of do
tasks to do functions inside the body so
the tertiary structure is a mix of all
the secondary structures all of the beta
sheets that we see here all of the Alpha
helixes that we see here all those
secondary structures combined together
to create the overall 3d shape of this
thing that is going to be the tertiary
structure the tertiary also means the
three so the primary one it's just amino
acids next to each other secondary to is
the little twists or switchbacks that
you're finding inside that protein and
then the third level is all the twists
and switchbacks making a big 3d
structure of that protein now many times
for something to function it as a
protein it can't just be by itself that
big 3d structure needs to meet up with
another big 3d structure and those two
things or three things or four things
combined together create the actual
structure the actual protein that will
do the function that will do the job
inside of the cell or body so that final
structural layer of many different
tertiary created 3d structures combining
together into a
superstructure is called the quaternary
structure so quaternary means for this
is the last layer I swear so at this
level what you're getting is the
combination of multiple 3d tertiary
structures to form one big molecule that
can do a function so an example that is
often used in this case is hemoglobin
hemoglobin molecules are four different
protein subunits that combined by
themselves so here they are different
colors here's blue we got a blue and a
pink and a pink and a blue and then they
all combine together these four pieces
to create the hemoglobin molecule that's
going to be doing the actual job of
these this particular protein so what
are some of the jobs that proteins can
do so there's tons do not want you to
memorize every single function of the
proteins no please don't which you can
kind of think about in general is if
there is a function if there is a job to
do in the cell if you need to create
energy if you need to break down a
carbohydrate if you need to change the
DNA by opening it up or closing it up
again it's gonna be done with a protein
so enzymes which speed up chemical
reactions these are proteins
transporting things so getting things
into and out of the cell especially
polar or ionic molecules these are
proteins signal molecules telling the
cell to start or stop doing something
and the receptors that those signal
molecules bind to these are often
proteins as well giving this all
structure collagen keratin melanin
myosin actin all of these kind of
structural things are proteins even
fighting off
infections antibodies these are proteins
as well so this is the smallest many
many many things that proteins do in the
body now the main thing that I want to
stress about proteins are their shape
that's why we went over the primary the
secondary the tertiary and the
quaternary shape of proteins because for
a protein form equals function so how
that protein looks is going to be
entirely dependent on the job that it
does and when a protein gets broken
either by a heat or by a change in the
pH of the liquid that it's in or
something other happens when that
protein loses its shape it's said to be
denatured and if a protein is not in the
right shape it can't do its function so
a denatured protein cannot perform the
function that it originally was going to
do
sometimes the denature protein can go
back to its original shape but many
times when a protein gets to denatured it's
just broken and it's gone and it's done
so one of the examples I like to think
about is an egg we all know eggs are
full of protein right if you want a high
protein diet reach for an egg
that's why Rocky, mr. Stallone cracks
all those eggs into a glass and then
drinks them in rocky which is gross but
you can getting a lot of protein now
when you first crack open an egg the
white of that egg is kind of a clear
goopy structure and when you fry it or
apply heat you're going to denature that
protein you're going to change its
physical structure and turn it from a
white kind of translucent goopy it's
kind of characteristic to this firmer
opaque type of of characteristic and you
can't go backwards right you can't
unfree an egg once you fried it so denaturing proteins is a very important
concept to think about because once
you've denatured them they cannot
perform their function anymore so their
particular shape is very important to
keep now the final molecule that we're
going to briefly talk about our nucleic
acids so nucleic acids are small
compounds they have three things as part
of them they've got a little sugar here
they've got what's known as a phosphate
group the phosphate group is going to
have phosphorus and oxygen in it it's
usually going to be charged too so this
is a charged end of this nucleic acid
now it's gonna have a nitrogenous base
which is basically another ring type
structure that has a lot of nitrogen in
it so a nitrogenous base some of the
things that nucleic acids are used for
this is our information storage molecule
so DNA the instructions to make proteins
and other things in the body as well as
RNA which is how those instructions get
to the places where those things are
made are made out of nucleic acids
that's very important but what will
mostly be focusing on for nucleic acids
are their energy potential so they are
the body's useful energy source ATP and
we'll discuss that molecule in a second
as well as what's known as coenzymes
that kind of aid protein enzyme function
things like NAD+ or are messengers
inside of and between cells so just like
eiconosanoids
those lipids that we talked about our
messengers nucleic acids can also be
turned into messengers so ADP is one of
the different kinds of messengers that
we'll find there are five different
types of nucleotides because the bases
here are different than nitrogenous
bases
there's adenine thymine uricil guanine
and cytosine now also these sugars can
be different but that's really more
information that we need to be then we
need to be getting into for the purposes
of this class so just quickly a little
bit on their function and a lot of their
function is tied into their structure so
nucleotide molecules here for the
purposes of this class are very
important in capturing or transferring
energy so ATP which is this molecule
that we see up here the T stands for tri
and the P stands for phosphate so this
ribose and nitrogenous base of adenine
are connected to one two three
phosphates this is a great transfer
molecule of energy because there's lots
of energy stored in this last bond
when this phosphate breaks off that
energy can go into work so some job in
the body that needs to happen means
energy injected into it that can happen
when this lost phosphate kind of breaks
off when that last phosphate breaks off
ATP turns into ADP and ADP is a very
important energy capturing molecule so
we could add a phosphate over here to
ADP and turn it back into ATP so we can
basically build ATP, ADP sorry di
phosphate into ATP in order to use that
last energy that we find that phosphate
again so these are two important
capturing in transferring energy types
of molecules NAD and FAD are basically
going to be the same thing only with
some other kind of components attach
them they also are going to capture and
transfer energy but I'm going to say
that kind of information for when we
look at them a little bit more in
metabolism as we said before they are
also
all cell communicators so CAMP camp
will find that one coming up a few times
when we're talking about cells
communicating with each other
it's basically adenine and ribose only
with a single phosphate group so if you
knocked off another one of these
phosphates and just had this component
that would be caMP and we'll talk about
that also later when we talk about
cell-cell communication so those are
kind of the main ideas to think about
for these four biological molecules that
would conclude this series of lectures
and as always email if you have any
questions yeah
