The Cell

Did you ever ask in math or science class, “Why do we need to learn this? When am I ever going to need to know this? 

As kids, we might have tuned out thinking all the terms and explanations were irrelevant to our lives. Or, as soon as we completed the final exam, we may have conveniently pushed all of our newfound knowledge into the back of our brains.

If so, it’s time to dig a little and pull at least some of what we learned back then into the forefront.

No, we don’t need degrees in microbiology to stay healthy.

But a refresher mini-lesson on the human cell won’t kill anyone. In fact, it could help to save your life!

Pay attention, now. There is a test at the end of this post!


Organisms are classified by the types of cells they have.

Eukaryotes are organisms whose cells have a nucleus and other organelles (mini-organs) within a membrane.

Prokaryotes are single-celled organisms that don’t have a nucleus or organelles with their own membranes.

Human beings are eukaryotes.

labeled parts of dissected cellThe nucleus inside human cells are the central part of the cell. It is considered brain of the cell, so to speak. Here’s where the DNA and RNA (the all-important instruction manual, in code) are located. The nucleus isn’t necessary located at the very mid-point of the cell but it stays away from the edge for extra protection.

The cell membrane is the semi-permeable, lipid (fat) barrier which allows some molecules to pass but keeps most of the organic chemicals inside the cell from escaping.

Cytoplasm is the material between the cell membrane and the nuclear membrane (or envelope) which wraps the nucleus. It is made of fibrous proteins and helps control movement of the cell and within the cell.

Organelles are specialized subunits within the cell. Each type of organelle has a specific function. In eukaryotes, organelles are wrapped in their own lipid membrane.

Mitochondria are considered the powerhouses or power plants of the cell, each with an inner and outer membrane. Here is where energy is produced in the form of ATP (adenosine triphosphate).

The nucleolus is sometimes referred to as the brain of the nucleus. It is a small, round, dense structure – the largest in the nucleus – responsible for making ribosomes, combining with proteins, and assembling signal recognition systems.

What are signal recognition systems, you ask?

The human body is an amazing, complex machine of nature. Just as humans communicate with one another, so do cells. And so do organelles.

As with human communication, some of is good and some not so good. Remember the game Telephone? Sometimes we get the wrong messages. Well, so do our cells. That’s all on this for now.

Let’s get back inside the cell.

Guess what nucleoplasm is? That’s right! It’s like cytoplasm within the nuclear envelope. It’s a type of protoplasm and includes soluble liquid material, chromosomes, nucleoli, and dissolved enzymes and nucleotides.

Proteins are synthesized from RNA in the ribosomes which float freely in the cytoplasm.

The transport systems within the cells are called the endoplasmic reticulum (ER). If ribosomes are attached to the ER, it is rough endoplasmic reticulum. If not it is smooth ER.

Golgi Bodies are the packaging plants of the cell. They take molecules and divide them into small sacs called vesicles. They can make rough ER smooth by removing it’s ribosomes. Flattened stacks of Golgi Bodies are called Golgi Complexes.

Still with me? We’re almost there.

Like humans, cells need a digestive system. That’s where lysosomes come in. They break molecules down into base components. The digestive enzymes used in this process are sealed off from the rest of the cell to prevent unwanted break-down of necessary material.

Lastly, vacuoles make up the storage system of the cell. They are single-membrane organelles which store nutrients or waste from all of the processing going on.

As you can see, each human cell is like a little factory. It has a command central, a communications system, a processing system, a production line, storage spaces, and even waste disposal.

Like any factory, when every skilled worker is doing their respective duties, things go smoothly. But, when one part of the system starts wearing down or slacking off for whatever reason, production slows or may come to a screeching halt.

What happens then?

No energy. No product. Toxic waste build up. Goals are met. Maybe the whole thing busts.

In human terms? Disease (dis-ease). Maybe death.

Okay. Ready for the final exam? Then, get out some crayons:)

cell part fill in the blank image


Special thanks to Crayola, Inc. for providing the fun exam diagram.