Cells can take in nutrients and get rid of waste. They can join together with each other and communicate. They can move, grow and reproduce.

Eukaryotic cells are in plants, animals, and humans. They are about 10 times as large as prokaryotic cells and can be almost 1,000 times greater in volume. Yet they are not more complex than bacteria and archaea. They are just more organised. Eukaryotic cells keep their genetic material within a neat little compartment called the nucleus.

All parts of the cell can be called organelles. The word organelle means “little organs” . They are to the cell as the organs are to our bodies.

The nucleolus is the somewhat round spot found within the nucleus of a eukaryotic cell. It is made of protein and a kind of acid. It is the nucleolus that is responsible for sending the messages that control the cell.

Chromosomes are tiny beaded threads made of proteins. Eukaryotic cells they are found in the nucleus. The chromosomes are the cell’s genetic material. They carry the cell’s DNA. DNA is short for deoxyribonucleic acid. DNA is divided into smaller units called genes. Basically, genes decide what a cell’s job in an organism will be. They also decide how a plant or an animal appears. Typical human cells have 46 chromosomes. Butterflies have 380!

A eukaryotic cell has a nucleus that acts as the cell’s brain. The round nucleus is surrounded by a wall called the nuclear membrane or nuclear envelope. Small holes in the wall allow molecules in and out of the nucleus. Messages can pass through each of these tiny holes as quickly as 10 per second.

Eukaryotic plant cells also have a very large vesicle called a vacuole. The vacuole takes up about 50 to 95 percent of the space inside the cell. Vacuole means “empty space”. Yet the vacuole does a lot. The vacuole presses outward against the cell wall. This helps keep a plant cell stable. It also allows the plant to grow tall. The vacuole serves as a space to store water, nutrients, and even waste. The vacuole can change its shape and size to suit the needs of the cell.

Ribosomes are like the cell’s protein factory. These tiny bead-shaped particles are found in both prokaryotic and eukaryotic cells, ribosomes form in the nucleus. From there they are sent out into the cytoplasm. The nucleus sends messages to the ribosomes using ribonucleic acid (RNA). The RNA tells the ribosomes which proteins the cell needs to grow. In prokaryotic cells, the ribosomes are smaller and are found throughout the cytoplasm.

Vesicles are sacs that store or transport matter, or get rid of waste. Lysosomes are vesicles in eukaryotic cells that act as recycling centers. They contain enzymes that help the cell break down unnecessary proteins, fats, and other waste. Lysosomes are surrounded by their own membrane. This membrane protects the cell from powerful enzymes. If the lysosomes were to break open, their enzymes could damage the cell.

Mitochondria are sausage -shaped structures in the cytoplasm of eukaryotic cells. Mitochondria are responsible for changing food into energy. This is why they are nicknamed the “power plant”. Mitochondria take sugar and other nutrients and convert them to ATP (adenosine triphosphate). ATP is what gives the cell energy.

The endoplasmic reticulum (ER) is a series of tubes found in eukaryotic cells. These tubes zigzag through the cells like roads and highways. The “roads” connect the nucleus to the other organelles. The ER can be either rough or smooth. Proteins travel through the rough ER. Proteins are either sent to the parts of the cell where they are needed or to the Golgi apparatus, where they are stored for future use. The smooth ER makes and stores compounds used for energy.

Inside a cell is jelly-like “stuff” called the cytoplasm. It is about 65% water.

Around the jelly is a cytoskeleton made of protein. The cytoskeleton is to the cell as bones are to our bodies. It’s what gives a cell its strength and shape. The cytoskeleton also helps a cell move without collapsing.

Everything that a cell needs to survive has to get inside from the outside. Then it needs to travel where it needs to go. If the amount a cell can hold inside becomes too big compared to its surface area, not enough food and chemicals can get inside fast enough. The cell stops growing.

The Golgi apparatus (also called the Golgi complex) looks like a bunch of deflated balloons. Extra proteins and fats are stored here until they are sorted, packaged and sent out. The Golgi apparatus can transfer proteins within the cell whenever and wherever they are needed.