* All living organisms are made up of cells. Whether it's a single-celled bacteria or a complex human, every living thing is built from these tiny building blocks.
* Cells carry out the functions of life. They take in nutrients, convert energy, grow, reproduce, and respond to their environment.
* Cells contain the instructions for life. They have DNA, which holds the genetic code that determines an organism's characteristics.
Here are some key characteristics of cells:
* Enclosed by a membrane. This acts as a barrier, controlling what enters and exits the cell.
* Contain cytoplasm. This is the jelly-like substance that fills the cell and houses the other components.
* Have ribosomes. These tiny structures are responsible for making proteins, essential for many cell functions.
There are two main types of cells:
* Prokaryotic cells: These are simpler cells, found in bacteria and archaea. They lack a nucleus and other membrane-bound organelles.
* Eukaryotic cells: These are more complex cells, found in plants, animals, fungi, and protists. They have a nucleus that contains the DNA, as well as other specialized compartments called organelles.
Understanding cells is fundamental to understanding all of biology, from the smallest bacteria to the most complex organisms.
