M.Ed., Stanford University
Winner of multiple teaching awards
Patrick has been teaching AP Biology for 14 years and is the winner of multiple teaching awards.
The cytoskeleton provides structure within a cell. It is found in all cells and is important for cellular motion (using structures such as flagella and cilia) and intracellular transport. Cytoplasm is the gelatinous material that fills the interior of a cell. It is liquid-like enough to allow for intracellular transport and motion but thick enough to hold everything in place.
As a teacher, teaching about the cytoplasm and cytoskeletons, sometimes it's kind of challenging because it's everywhere. It's kind of like trying to teach a little kid what is air. If you point to it and say," There it is", they say "what?" "The air, it's right here see? There," "Where?" They've see nothing, because it's actually all around.
And whenever you look at a diagram of the cell and you see an arrow pointing to what looks like nothingness, they're often typically pointing at the cytoplasm.
So, what is the cytoplasm? Technically the cytoplasm is a location in the cell. The name cytoplasm means literally the cell cyto, plasm means gooey liquid. So this means literary, the gooey liquid of the cell. When people were first looking through microscopes at cells, they could see that there was an outside of some sort and because they were looking at plants they called that the cell wall, and then later on they figured that there's a membrane there. And then they saw that there is something in the middle and they called that the nucleus which means the middle. And then everything in-between looked like nothing and just there was a space. So they called it the gooey liquid. That's of the cell, so cytoplasm. We know now that that location is actually [IB] full of other organelles. So when most people talk about the cytoplasm they're still talking about that liquid but it's actually, technically according to some of the test writers, a location. So beware when somebody's asking questions about that. So we call that liquid more properly, the cytosol which means the solution or liquid of the cell.
What goes on in the cytosol, because it's mostly water, it allows it to dissolve materials and allows them to easily diffuse from one place to another inside the cell. It's also [IB] of enzymes and proteins and even the ribosomes, they're floating around inside of that cytoplasm I'm sorry, cytosol and allows a lot of important chemical reactions. For example, glycolysis, the initial breakdown of sugar happens in the cytoplasm.
Very similarly, in literally technically, the cytoplasm is the cytoskeleton. This one, if you look at the name cyto-skeleton, you're starting to realise hey, it's the skeleton of the cell. And it's made up of microtubules and microfilaments much like your skeleton is made up of bones and ligaments, and these microtubules and microfilaments give structure and shape to the cell.
Let's take a look at this. Now here we see the standard cell diagram, and you can see these little lines here. Those are what they labelled the microtubules and microfilaments of the cytoskeleton. And this wide area here, that's the cytoplasm.
Now I've always laughed when I've seen these drawings where they show, let's see one, two, three, four, five microtubules or microfilaments. Let's take a look at what it would really look like. We look at this. All these green stuff is just a few of the microfilaments that are within the cell under the microtubules. A cell is [IB] full them. If you could see the proteins that make up the cytoskeleton, it would look like Spiderman went insane and just started spraying his webs all over the place and they're made up of the same specialized proteins that make up your muscle. And just like your muscle is able to move your arms around, these tubules here, these filaments here they can grab organelles and carry them from where they're needed and they can also push out the membrane and this is how your white blood cells are able to shift and move to chase down some bacteria. And there you go.