Cells - Course Trailer

Hello.

Now, when you look at me right now, you probably think that it's me, Sal, talking to you. But really, what is talking to you is a society of over 30 trillion cells that have somehow collectively convinced itself that it is Sal.

What we're going to study in these lessons are exactly that: that even though we think we're one unified organism, where frankly, all the living things we see are, that we say, "Oh, that's a plant, and that's a frog, and that's a pigeon, and that's a cell," it's not just a cell. It's made up of trillions and trillions of things called cells which, well, as we'll learn, they're the fundamental building blocks of life.

What makes them alive? If we were to go at an even more basic scale, all of a sudden, things are not alive. It's a fascinating philosophical question. You might think that one 30 trillionth of me might be some kind of small simple thing. But, as we'll see, there's a whole universe in each cell—unimaginable complexity that scientists are still trying to understand.

In these lessons, we're going to talk about the history of mankind trying to struggle with the basic units of life. Is there a basic unit? How do we understand how it works, also known as cell theory? We're going to learn about the different types of cells that even exist: things like prokaryotic and eukaryotic cells; things like plant and animal cells—what's similar, what's different.

Finally, we're going to learn about parts of the cell, especially things like, say, the membrane, which in and of itself is a fascinating and complex piece of machinery.

So, we're about to delve into some of the deepest ideas that mankind has always faced: what is life? What makes one thing alive and another thing not alive? What is the most basic unit of life? Where did it come from? We're going to touch on all of those in the next few lessons.

And I encourage you, if you want to dive deeper and get more context and get practice to make sure that you're understanding these concepts, look at these lessons on khanacademy.org.