Endcytosis

You're too naive, Cellnosuke.

How did you plan on eating the onigiri you bought?

You don't have a mouth.

So, in today's lecture, we will learn how cells without a mouth take in large substances!

Listen attentively!

What we're going to learn in today's lecture is endocytosis.

Indeed, it does sound like a difficult word.

But what if I tell you that endocytosis is the name for a way of eating? Would that make it a bit easier to understand?

Don't worry, I'll explain it slowly and steadily.

I did say at the beginning of the lecture that eating through the mouth is incorrect, didn't I?

That's because cells don't have mouths.

Did you think about something unnecessary?

Well, it's fine. The correct way for a cell to eat is by surrounding the substance with the cell membrane and taking it into the cell.

Not really.

This is the series of steps in endocytosis.

Could you imagine it at least a little bit?

That's a good question.

Do you remember when I explained in a previous lecture that the cell membrane has small holes like a sieve used in the kitchen?

Then you should tap on my speech bubble right away and review the lecture.

Now, as I conveyed in the previous lecture, there are large substances that cannot pass through the small holes of the cell membrane.

Specifically, we're talking about macromolecules like proteins.

When we need to take them into the cell, we use the mechanism of endocytosis.

As a supplement, there are two things I want you to remember.

First, when performing endocytosis, the cell requires energy in the form of ATP (adenosine triphosphate).

This type of transport that utilizes energy (ATP) is called active transport, but we will discuss it in more detail in a future lecture.

And one more thing, the substances that are taken in become enclosed in small vesicles within the cell.

Wrapping the substances in vesicles makes it easier to carry out further processes such as decomposition while keeping them contained.

There is a cellular process called autophagy that takes place inside the cell.

Dr. Ōkuma's discovery, which earned him the Nobel Prize in 2016, is indeed significant. As you continue to study further, you'll find that this kind of detailed knowledge can be useful.

However, diving into too many details right away can sometimes make studying overwhelming. So, for now, it's enough to have a general understanding and remember these additional points as supplementary knowledge.

That concludes today's lecture.

Before we wrap up, let's solve a problem.