Parts of a Cell Biology Bits
Written by: Karla Moeller

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Flashcard facts and information about the parts of the cell

Biology Bits stories are a great way for you to learn about biology a little bit at a time. We’ve broken down information into pieces that are very tiny—bite-sized biology cards. Cutting out the cards will let you organize them however you want, or use them as flashcards while you read.

This set of bits will teach you about the tiny world on which life depends: the parts inside a cell. To learn more about the science behind your cells, visit Building Blocks of Life - Parts of the Cell.

Play the slide show from the beginning or pick a slide to begin with by clicking on a slide below.

Illustration of skin, at a microscopic level.

Life cannot exist without cells. Your body is made of many types of cells. Cells come in all kinds of shapes and sizes. They make your skin, your bones, your muscles, and much more. For this reason, it is important to understand what makes cells work.

Illustration of an animal cell versus a plant cell.

All cells are made of tiny parts. We call these parts organelles, a word that means "little organs". Cells can have more or fewer types of organelles. Most plant cells have some parts that are not found in animal cells. These parts let plants make food using energy from the sun.

Close up illustration of a cell membrane.

In pictures, the insides of cells often appear to have very clear shapes. But from the outside, cells look more like they are covered in a thick film. This film is the plasma membrane, and it covers the whole cell. The membrane is made of two thin layers of fat molecules (lipids) called fatty acids. Each fatty acid has two sides—the head and the tail. When the layers match up, the tails face the inside of the membrane and the heads point out.

Close-up illustration of a cell membrane channel.

Molecules need to get in and out of cells. But with a membrane that covers the whole cell, how can stuff move in and out? Little holes in the cell membrane let items travel in or out of cells. These holes are made of special proteins that can move or open in the middle. We call them channels or pores. Certain parts of the membrane also let some water through.

Illustration of the cell nucleus.

Welcome to the nucleus. It is the largest organelle and the control center of the cell. It holds instructions on how to build and run the cell. We call these instructions DNA, which is short for deoxyribonucleic acid. These are the instructions that made your whole body. The nucleus also holds a smaller part of the cell called the nucleolus. This organelle helps build ribosomes, which are cell parts that make proteins.

Illustration of both rough and smooth endoplasmic reticulum.

In the cell is a structure that looks a bit like a maze. It sits just outside the nucleus. This structure is the endoplasmic reticulum (ER), and it is made of thin-walled tubes. This organelle makes most of the proteins and lipids, like fat, in the cell. Some of the ER is rough, with little balls built into the wall. This rough ER makes proteins. The other ER is smooth. It makes lipids and stops harmful materials from hurting the cell.

Illustration of a ribosome.

Proteins help your body do all kinds of jobs. They're important, so there is an organelle that just helps make proteins. We call it the ribosome. Each ribosome is made of two subunits, a large one and a small one. Many ribosomes sit in the wall of the endoplasmic reticulum (ER). Some are also found in other parts of the cell.

Illustration of a Golgi body (or Golgi apparatus).

Cells are busy. They make items and ship them out of the cell to other cells in the body. How does a cell keep track of it all? The Golgi complex is the shipping center of the cell. It get proteins from the endoplasmic reticulum, wraps them up, and ships them out of the cell. This organelle was named after the scientist Camillo Golgi, which is why Golgi is capitalized.

Illustration of cell mitochondria.Illustration of a chloroplast.Illustration of cell vescicles.Illustration of cell vacuole.Illustration of a cell's cytoplasm. Illustration of cell wall.Illustration of peroxisomes.Illustration of centrioles.Illustration of cell lysosomes.Illustration of cytoskeleton.Cartoon face talking

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