Hi! I'm Captain Cellular. Let's go explore the                 Critter Cell Cosmos!

  We made it to the Cell Membrane Belt! It's made up of phospholipids and proteins. The membrane is semipermeable, meaning that it can allow some things in and out, and some things not to come in at all. Its made up of a bilayer, which is two layers. This also helps keep some things in and out. Luckily, my spaceship is small enough to pass through.

Uh oh! My spaceship won't go unless you answer a question! How many layers does a cell membrane have?

That's right, let's go!

We have now entered the Cytoplasm Vacuum. Cytoplasm is kind of like jelly, but it's made up of salt, water, and other organic materials. Cytoplasm is responsible for holding the other organelles in the Critter Cell Cosmos. It also protects them, and helps some of them move freely. Let's go find the Necleus Star!

Oh no! My spaceship wont move again. You need to answer another question.  What is one of the purposes of the Cytoplasm Vacuum?

That's correct! Let's move on!

This is the Nucleus Star. It is held together by a Nuclear envelope, and has Nuclear Pores. The Nucleus is basically the Critter Cell Cosmos' control center. Inside of the Nucleus, is the Nucleolus. It makes the DNA for everything in the Critter Cell Cosmos.

Luckily, the next part of the exploration is connected to the Nucleus by the Nuclear Envelope. This is the Endoplasmic Reticulum, or the ER. There are two of these. This is the Smooth ER, or the SER. Just like it sounds, it's smooth. It's smooth because it has no ribosomes on it, unlike the Rough ER, or RER. The SER produces things like hormones and lipids. The rough ER produces proteins. Speaking of ribosomes, lets go find one!

Here on the other side of the Nucleus is the RER. Those little dots on the RER are ribosomes. The ones floating are also ribosomes. The ones that are floating are called free ribosomes. Free ribosomes make proteins for inside of the cell. The ones that are stuck to the RER are called bound ribosomes. They make proteins for outside of the cell or for lysosomes. Let's go find a lysosome!

Not again! You know the drill. Which ER makes proteins? The SER or the RER? I really need to get this fixed.

Great job! Let's get this ship moving.

This is a lysosome. They're basically the trashcans of the Critter Cell Cosmos. They're Spheres that are filled with hydrolytic enzymes. They take waste and debris, and use the enzymes to break it down. Let's go find a vacuole.