Today we will discuss the
cellular level of organization
which is the basic functional
unit of our human body.
So in this lecture, we will discuss
the different structures of the cell.
This can be divided into three
The nucleus of the cell, the plasma membrane
of the cell and the cytoplasm of the cell.
So we will work our way from the outside-in
starting first with the plasma membrane
which is going to separate the internal
and external environments of the cell.
Then we will move into the cytoplasm
where we will discuss the cytosol
as well as different organelles that
perform different functions in the cell.
And then finally we'll conclude with the
nucleus including its chromosomes and genes
which allow for the cell,
allow our body to function.
Alright, so let's start with
the plasma membrane.
The plasma membrane is
a flexible yet sturdy barrier
that's gonna surround the
inside of the cell and again,
it's gonna provide a barrier between the
external and internal environment of the cell.
When you think of the plasma membrane,
even though it is a barrier, think about bubbles.
You know how a bubble, it's a very
thin film and it's made up of lipids.
That's exactly how our
plasma membrane is made of.
It is a double lipid bilayer
that's made up of phospholipids
where you have phosphates facing
the outside and the inside of the cell
and then in between, you have
fatty acid tails facing each other.
This is actually really important for
the structure of the plasma membrane
because it allows it to form this barrier.
The phosphates are aqueous or
hydrophillic and they are attracted to the water
in the internal and external environment.
Whereas the fatty acid tails hate water and are
hydrophobic and therefore they point inward
and so this double layer is there
and it creates this barrier.
The plasma membrane is not a
static feature of the cell.
It is extremely dynamic where the lipids
are moving and flowing throughout
and as well it's studded with different structures
such as different types of proteins and cholesterol
and other things that allow the plasma
membrane to actually perform its functions.