Hi. It's Mr. Andersen and welcome to biology essentials video 43. In this chapter
or in this podcast I'm going to talk about major cellular organelles, what they are and
what's the most important things that you should remember about them. But what we tend
to do is we over simplify the cell. In other words you've learned since you were in 7th
grade about all the parts of a cell. But what you don't understand is how complicated and
how amazing it is. And so I'm recommending this video. It's called Inner Life of a Cell.
It's like 5 minutes long. I'll put a link to it on YouTube here. But what it is a group
at Harvard who tried to use computer modeling to show you what a cell really looks on the
inside. And so this right here is a motor protein that will literally walk transport
vesicles around in a cell. It's amazing to see how active it is inside a cell. And we
tend to not to do service to that. So please watch that video. And then come back. So in
this concept map it's a little bit different than the other ones that I've done. I decided
to start right here at the nucleus which is kind of the control center of the cell. In
other words it's got the information. The blueprints. And it's also gene controlled.
It's telling other parts of the cell what to do. So if we work outward from that, right
on the outside of that we have the ER, endoplasmic reticulum. We have both smooth and rough ER.
Now the rough ER is rough because it has little ribosomes on it. So what do ribosomes do?
Those are going to be where we produce proteins. That's the site of protein synthesis. The
rough ER gives us a lattice where we can actually do that. And we can make different constituents
of the cell. Parts and chemicals that are going to be used throughout the cell. Before
we keep going with the rough ER, the smooth ER is really responsible for making lipids.
It's also responsible for breaking down the toxins but it's going to make lipids. And
remember almost all the parts of the cell are going to be made up of lipids. So smooth
ER is super important. So some of the ribosomes float around out here. But some of them are
going to be found right on the rough ER. And so they're going to make proteins. Now those
proteins will be trapped in transport vesicles brought to the Golgi complex. From there they
can go to different parts of the cell or outside the cell. It's also where we produce lysosomes.
And lysosomes are important in breaking down material when it's not used. Another portion
of, especially plant cells, is the vacuole. Vacuole, it's importance is in storage. For
example all plant cells have a central vacuole. It's going to allow them to regulate the amount
of water. And then I put these two over here. And they both deal with energy. So these are
the mitochondria and the chloroplasts. Remember mitochondria are found in all eukaryotic cells.
And remember, we're talking about eukaryotic cells. The moment you ever hear me talk about
eukaryotic, missing an O, the moment you hear me talk about organelles you know we're talking
about eukaryotic cells. So all eukaryotic cells have mitochondria. It's how we make
ATP. But then plant cells are going to have or producers are going to have chloroplasts.
And that so they can make sugar so they can use it by there mitochondria. So, let's kind
of get to each of those. Start with a ribosome. So where is the ribosome made up of? Well
maybe better yet to talk about what it's made up of. So this right here is a ribosome. It's
from a bacteria called thermus thermophilus. And so the blue things in this picture right
here are going to be proteins. And the brown part is going to be a continuous piece of
RNA called ribosomal RNA. And so it's made up, ribosomes are made up of two parts. They're
made up of proteins. And then they're made up of RNA. And so those two parts together
are synthesized in the nucleolus, which is going to be found in the nucleus. And what
you essentially get are two subunits. So you're going to have a small subunit. And then you're
going to have a large subunit. And then what goes through the middle is going to messenger
RNA. And so what are we doing here? We're doing translation. We translating the message
of the messenger RNA to a protein. And so where does this take place with ribosomes?
It could take place right in the cytoplasm or it could take place on the ER. So what
is the ER? ER is the endoplasmic reticulum. It's usually attached right here to the outside
of the nucleus. So it's a membrane that folds upon itself. It's going to have ribosomes
that sit right on that. So it can actually synthesize proteins. And those proteins end
up going to the inside. So these little green dots here would be showing proteins or bits
of proteins that are put together. This is what it looks like under a microscope. You'll
find that there's also smooth ER. Smooth ER doesn't have ribosomes on the outside. Mostly
it's where we synthesize lipids inside the cell. But function of the ER is to kind of
give us a lattice so we can build things. And so if we're talking about the cell as
a factory this is kind of the factory floor with the workers fitting on the top of it.
That's definitely going to be the endoplasmic reticulum. If we go to the Golgi apparatus,
or the Golgi complex, it was discovered by this man, Camillo Golgi who lived in the Austrian
empire. Died in like 1926. But he wasn't famous for Golgi complex. It's how we all know him
for. But he was really good at staining cells. And figuring out the parts of the cell using
stains. So you'd use silver, silver nitrate. A number of different stains to figure out
how neurons work, nerves work. Won a Nobel Prize but he's most famous for discovering
this. And he used staining features to discover the Golgi apparatus. What's the Golgi apparatus
do? Well in general it takes information that's produced in the endoplasmic reticulum and
then it shifts those to different parts of the cell. And so I like to think of it as
like the UPS of your little factory. Material is made in the endoplasmic reticulum. It's
moved to the cellular UPS. And then it's going to move on it's way. Either to different parts
of the cell or even outside the cell. That's the Golgi apparatus. Lysosome is next. And
we could actually trace that pathway again. So what does the lysosome do? Well lysosome
right here has digestive material inside it. So it's got a bunch of digestive enzymes in
it. And what it does is it digests material. And so if we're infected for example, let's
say we catch a bunch of viruses inside of us. That lysosome will fuse with those viruses
and it creates something called the phagosome so we can break it down. Or this can dissolve
mitochondria that's not functioning. Or it can even kill cells. And so lysosome I refer
to as like the suicide sac. It has enzymes. Where did those enzymes come from? Well they
came from the ER. They eventually went through the Golgi apparatus and a lysosome was produced.
And so lysosomes are really important in breaking down material when it's not needed anymore.
And the last two are going to be energy producing inside the cell. So the mitochondria. We've
talked about, as far as cellular respiration goes. It's got an inner membrane which is
going to be this red portion, or excuse me an outer membrane and then it's going to be
the inner membrane which is going to be the yellow membrane here. That membrane is folded
over and over and over again. And so we call this folding the cristae of a mitochondria.
These inner folds. The outside is really really smooth. But what you get then is this inner
membrane space, which is the space right here. So going back over cellular respiration, where
does everything occur? Remember glycolysis is going to take place outside the mitochondria.
The Kreb cycle is going to take place on the inside. And then this electron transport chain
is actually going to take place right along that inner membrane. And that space is super
important remember because we can build up those protons on the inside. Make as much
ATP as we can. And so the reason this is folded is to increase surface area. If you ever see
folding, it's to increase surface area. In this case it's to make more ATP. And then
last two I want to talk about are the vacuole and I lump that in with the plants. A vacuole
is going to be mostly for storage. This would be the vacuole. And then the membrane around
the outside of it is called the tonoplast. But what does it do? We store material inside
that. So every plant is going to have a central vacuole where they put water and they can
regulate the amount of water that they have. But if it's the petal of a plant they're going
to have, for example, colors inside here that give it the colors of the petal. Or they're
going to have nasty chemicals inside their vacuole. So if you eat it they've got toxins
inside there. It's also important, vacuoles in cell growth as well. So vacuoles I like
to think of them mostly as storage. And then the last one is going to be the chloroplasts.
Here's a bunch of chloroplasts inside a typical plant cell. And if we ever see a lot of chloroplasts
that means we're doing photosynthesis. The parts of it that you should know are going
to be this membrane right here is called the thylakoid membrane. So this would be the membrane
right here. If we have a bunch of stacks of these thylakoid membranes together we call
that a grana. And then there's going to be a liquid portion on the inside. That liquid
portion is called the stroma. And so again, going back over photosynthesis, the light
reaction is going to take place on that thylakoid membrane. And then that Calvin cycle is going
to take place in the stroma. And so the reason we have increase surface area is to absorb
more light. Because the chlorophyll molecules remember will sit right in the thylakoid membrane.
But we're also increasing chemical reactions. So those are the major parts of the cell.
There clearly are more. But those are the big ones. And I hope that's helpful.