The building blocks of life

Cells: The building blocks of life

Cells are microscopic organisms that make up all living things. You are made of cells, I am made of cells, the grass is made of cells, even your leftover pizza has cells! Cells make up everything that is living or has lived.

Cell Theory

Cell theory is a set of basic facts about cells. There are three main parts to cell theory:

  • All cells come from existing cells
  • Cells are a fundamental building block of life and the most basic.
  • ALL living things are made of (one or more) cells
The Cell Theory Song


Cell discovery is controversial. Some say Robert Hooke discovered cells when he looked under a microscope at a piece of cork. He saw hundreds tiny rooms then looked like cells (were monks sleep). Thus the name "Cells".

The Cell Theory was a combined effort from Matthias Schleiden and Theodore Schwann.

Matthias studied plants and found that all plants were made of cells.

Theodore Schwann studied animal cells and found that all animals were made of cells.

The wacky history of cell theory - Lauren Royal-Woods

Small to Big

Cell, tissue, organ, organ system, organism


Animal Cell > Tissue > Muscle > Muscle System > Person

Explanation: You have 1 animal cell. Lots of animal cells can make a tissue. Lots of tissue makes an organ, like a muscle. Lots muscles make up the muscle system, and that muscle system is inside a person.

Procaryotic and Eucaryotic

Cells have two main categories, Procaryotic cells and Eukaryotic cells. The largest difference is a nucleus. A Eukaryotic cell has a nucleus, while a Prokaryotic cell does not.

Eukaryotic: Plant cells, animal cells, an apple, a cat, etc.

Prokaryotic: Mainly bacteria

Prokaryotes and Eukaryotes

Plant Cells and Animal Cells

Plant Cell

I love making glucose! But... I always lose it to my mitochondria :/

Click on the photos to find out more!

Animal Cell

I love animals! They're so cute :D The kittens and the puppies... I could just eat them up! Actually, I couldn't. I would be eating myself O.O

Click on the photos to find out more!


A cell's organs


A nucleus is almost the brain of a cell. It controls it. All the DNA is inside the nucleus. Under the microscope, it may be seen as a large black dot in the cytoplasm. All prokaryotic (animal and plant) cells have a nucleus.


All cells, including eucaryotic, have cytoplasm. Organelles are suspended in cytoplasm.


This is an organelle that breaks down glucose to make energy for the cell in a process called "cellular respiration". This energy is called ATP (or adenosine triphosphate). ATP powers the cell, and because the mitochondria makes the ATP, the mitochondria. This makes mitochondria very important. Even plant cells need mitochondria to break down the glucose that they made during photosynthesis. Luckily, each cell generally has more than one.

Cellular Respiration Formula:

C6H12O6 + 6O2 > 6CO2 + 6H2O + 36 (or 38) ATP

In words:

Glucose + 6 Oxygen turns into *6 Water and ATP (About 36 or 38)

*Water is a waste product of cellular respiration

Cellular Respiration and the Mighty Mitochondria


Ribosomes, in plant and animal cells, follow instructions from the nucleus and make proteins for the cell. Proteins are needed to help around the cell. An example of this would be to repair the cell after sickness. The biggest difference between ribosomes and the ER (endoplasmic reticulum), is that ribosomes specialize in smaller things.

(Note for the image: The ribosomes are the tiny dots)

Cell Wall

A cell wall can be found on the border plant cells. They lay directly outside the cell membrane and give plant cells their structure and box like shape. It acts like an exoskeleton for plants!

Cell Membrane

Cell membranes are found on all cells. It lets in and out certain things, like a doorman or castle wall. Cell membranes help protect what is inside, and keep it together. If the cell membrane brakes, the cytoplasm and organelles will spill out and the cell will die.

Around the nucleus, there is a nuclear membrane. It is almost the same as the cell membrane, except it surrounds and protects the nucleus rather than the entire cell.


Chloroplasts are found in plant cells and hold the chlorophyll for photosynthesis. If it wasn't for the chloroplasts and photosynthesis, plants wouldn't be able to get glucose to make energy! Under the microscope, you can see chloroplasts clearly as green circles. The many green chloroplasts give plants that green color. Parts of plants that are not green, do not have chloroplasts.

Photosynthesis is when a plant takes in water, sunlight, and carbon dioxide, and turns it into Glucose (a basic sugar). The formula for photosynthesis is exactly the opposite of the cellular respiration.

Formula for Photosynthesis:

6CO2 + 6H2O > C6H12O6 + 6O2

In words:

6 Carbon Dioxide + 6 Water turns into Glucose and 6 Oxygen.

Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER), is a lot like a ribosome. One of the biggest differences is that the ER takes care of large proteins and ribosomes make smaller proteins.


Vacuoles are in plant and animal cells. The vacuole can store water, protein, or waste. In animal cells, there is generally a very large vacuole. Infact, in a plant cell, then cell is almost entirely a huge water filled vacuole. In an animal cell, the vacuole is barely visible. Animals don't need to store as much, so they don't need a large vacuole. Plants must have a large store of water so they will have some on days it doesn't rain.

Golgi Apparatus

The golgi apparatus is in all Eucaryotic cells. It works like a packaging plant, because it "packages" or group certain proteins together before sending them away to another organelle or outside the cell as waste.
Cell Craft

An amazing game that is both fun and educational