Transcription
All right, so the next type of molecule that we are going to talk about in this diagram are the big purple blobs because there are a lot of them and they are pretty important. So, what kind of molecule are these big purple blobs? These are, um, proteins. So, anything purple on here is a protein. Whoops, I am having a hard time using my tablet today.
All right, so, uh, these proteins, um, oh my gosh, there are there's so many different types, and we're gonna get more into proteins, um, throughout the rest of this unit. Uh, we're gonna spend a lot of time on them. In fact, honestly, I could probably tell you that about three quarters of the rest of Bio 181 through December, uh, through the end of the course, is going to be about proteins.
So, what do proteins do? Well, they do many different jobs in the membrane, but one of their main jobs here is to act as a transport, um, transport tunnel. So, we'll, in a few, you may have already seen the video about what can and cannot get through the membrane. There, we've already talked about how the membrane is selectively permeable, and so not everything can just kind of wiggle its way through. Not all kinds of substances can do that. In fact, most can't. So, but that doesn't mean to say that your cells don't don't need things to get inside them and to leave them. For example, you need to get sugar, glucose, inside of your cells because the sugar is used by the living cells on the inside for energy. And then your cells create all kinds of waste products that they need to get out. So, things do need to cross the membrane, but they can't necessarily wiggle through. They have to have a different route to get in. And so, a lot of these proteins are have a function, um, as transport proteins. We call them transport proteins, uh, and sometimes you'll also heard them called channels. A channel is kind of almost the same thing as a transport protein, uh, it provides a way for things to get into and out of the cell.
So, you could almost imagine, see this kind of protein here, it looks like it's a solid blob. It's really not a solid blob. It's actually a structure that's kind of got gaps and holes in it, and we'll get to what how it's made in a few, in a week's time. But if you can imagine this having like a hole running through it, I'm gonna try and draw a picture here like this, like a tube running through. Something could go in this end and it could come out that end, and it was able to pass from the outside of the cell to the inside of the cell without having to actually cross through between the phospholipids. It went through its own little private tunnel, kind of thing.
So, these transport proteins are incredibly common in your cell membranes, and you have a lot of them. And why do you need a lot? Because, um, you, you have a different transport protein for every single type of molecule that you want to get into or out of your cells. So, this tunnel here, I shouldn't have erased it, let me put it back. This tunnel here might be a tunnel, this tunnel might be a tunnel for, um, just one kind of molecule, say glucose. So, let me draw this on here if I can get it. So, this is my glucose tunnel. I'm out of practice with my little stylus thing here. So, this tunnel could have glucose go in one end and come out the other. But this one over here, this might be a tunnel for something completely different. Maybe this is a tunnel for an amino acid or something else. And so, forever, they're personalized. Um, maybe this is allowing something else to come out. And that's why you need so many of them. All the different things that you need has its own personal, each type of molecule has its own personal tunnel.
The other thing is that these tunnels aren't always just open like this, that the molecules can just kind of wander in and out as they want. The cell has the ability to sort of close off the tunnel if it wants to, like maybe think of like a flap that comes down to kind of close it off. So, this is how the cell can control what it lets in and what it lets out, when it can open and close these tunnels or channels by opening and closing kind of gates to let things in and out when it wants. So, these transport proteins are incredibly important, and they play a great role in regulating what can go in and what can come out of your cells.
There are many, many other jobs for proteins, um, in the cell membrane, like there's, there's proteins here that are stuck to other proteins on the inside. There's a whole bunch of things going on here. We'll get into that later on in the class. But for now, at least, as long as you recognize these purple blobs as proteins, and that one of their major jobs in the membrane is to provide these transport tunnels, that's a great start.