Finally we need to look at our other membrane bound organelles.
Mitochondria are the ones that we'll focus on in cells
for this course because those are found in animal cells.
Chloroplasts also come about in a very similar way
and have quite similar structure but they are in plant cells.
The mitochondria has some specific anatomy that we need to look at
because later in the course we will look at
how cellular respiration occurs.
And it involves understanding the structure of mitochondria.
So mitochondria have an outer cell membrane
as well as an inner cell membrane.
We call the space between those membranes the intermembrane space.
And then the space all the way in the middle,
we call the matrix.
Floating around in the matrix,
which is sort of the soup inside the mitochondria,
we will find both ribosomes because mitochondria
can actually produce some of their own proteins
we'll come to that in a little bit, as well as some DNA.
DNA molecules are circular DNA, very much like prokaryotic DNA.
And that's going to lead us into talking about
where these membrane bound organelles may have come from.
So I had introduced earlier in this lecture the idea that membranes
came, these compartmentalization came from membrane invagination.
That would be called the endomembrane theory.
Now, how did these other organelles perhaps make their way into
becoming organelles inside of a eukaryotic cell.
Recall eukaryotic cells.
They're about ten times larger than prokaryotic cells.
And it's proposed that things like the nucleus and mitochondria
may have arisen from other prokaryotic cells
becoming enveloped or endocytosed, pulled in like food,
into larger prokaryotic cells.
The nucleus could have arisen this way.
The mitochondria could have arisen this way.
And chloroplast could have arisen this way.
Now keep in mind that all three of these organelles
have DNA of their own in them.
The DNA in the nucleus has changed significantly.
However, the DNA in chloroplast and mitochondria are still single
circular molecules or plasmids of DNA that we'll see inside of those.
So it's likely that they have this double membrane structure
because they were essentially swallowed up by a larger cell.
And perhaps, they had more ribosomes in them, or perhaps,
they were able to make more ATP and that became a successful strategy
and so eukaryotic cells could have come about this way.
So the endomembrane theory, and endosymbiotic theory are both ideas
about how eukaryotic cells could have arisen from prokaryotic cells.
And I think it's important to discuss that
because it helps us remember that the mitochondria
have some of their own DNA as well as ribosomes of their own
that look like prokaryotic DNA.
So in closing this lecture,
we've explored nuclear structure.
So now you should be able to explain the structure of a nucleus,
including some basket anatomy
and how they control flow of things in and out of the nucleus,
as well as being able to describe the roles of
each of the organelles in the endomembrane transport system.
How do we make proteins to go.
And finally, we covered how eukaryotic cells
could have become so much more complex than prokaryotic cells.
So I'd thank you for your attention
and I look forward to seeing you again in the future lecture.