Bob was taking a biology class and his homework was to research cells, but when he got home, his internet was down so he had to use his critical thinking skills to solve this problem.  He decided to ask his older brother Bill about cells.  Bill had already taken biology and loved it.

Bob:  Bill, what are cells and what do they do?

Bill:  I thought you would never ask Bob!  Cells make up all living things.  They are very small but an extremely important part of life.  In fact, they are considered the building blocks of all life.  You are unable to see them with the naked eye, but many scientists have observed them under a microscope.  They can be all different sizes depending on what organisms the cells belong to.

Bob:  Wow that's so cool!  What are cells made up of?  Do all of their parts that they are made up of do the same jobs?

Bill:  Organelles are what makes up cells.  These structures all have their own specific job that they perform inside of cells.  For example, the ribosomes are responsible for producing proteins inside the cells.  Most organelles can be found in prokaryotic and eukaryotic cells but some are only found in one or the other, such as the nucleus which is only found in prokaryotic cells.

Bob:  When was the idea of cell theory developed?

Bill:  The idea of cell theory was developed throughout the 1600's.  Many scientists helped contribute to the cell theory.

Bob:  How did these scientists discover these things called cells?

Bill:  Cells were first discovered by scientists looked at different objects under a microscope.  They thought that the object looked like multiple rooms in a building.  After seeing this, many scientists became inspired to study these "cells".

Bob:  Can you teach me a little bit about some of the scientists that helped develop the cell theory?

Bill:  Of course Bob!  The scientists that I will teach you about are Robert Hooke, Theodor Schwann, and Matthias Schleiden.  Robert Hooke made many contributions to cell theory.  He was the first scientist to observe cells under a microscope when he observed a piece of cork.  He also came up with the theory that all cells come from other cells.  Theodor Schwann made many contributions to cell theory as well!  He helped develop the theory that all animal and plant tissue are made up of cells.  Also, all cells in an individual organism are identical.

Bill:  Finally, there is Matthias Schleiden.  He first defined the cell as the basic unit of a plant structure and later on declared cells the basic unit of animal cells.  He also studied the common elements among all plant and animal cells.

Bob:  Wow!  I learned a lot today.  I can't wait to tell my teacher about everything I learned!