Why I Like Being a Multicellular Organism

Multicellular organisms have a simple definition: one organism is composed of more than one cell. Unicellular organisms exist with only one cell. Plants and animals are almost always multicellular, whereas prokaryotes and protists are usually unicellular.

The downfall of being a multicellular organism is that we are susceptible to cancer. Cancer is caused by cells that cannot stop growing and dividing; the abnormal growth is what we refer to as tumors.

Consequence of cancer aside, multicellularity has many benefits. The greatest benefit is that each organism has cells that are specialized to complete specific tasks. This allows the labor of survival to be spread across many groups of organs, tissues, and other specialized cells. Unicellular organisms have all the same parts performing all the same functions for everything. Things get done, but sometimes it is best to leave certain things to the experts, no?

Multicellular and unicellular organisms also have differences between their respective genomes. Multicellular organisms need to produce more proteins in a wider variety, so they also have a larger genome that allows them to code for a larger proteome. The need for a larger selection of proteins is threefold:

1) Cells need to organize themselves more completely and therefore need to communicate most effectively. Proteins are required for proper cell signaling and therefore the ultimate organization of the cells into tissues and organs.

2) Keeping all the cells of different types and locations in the right places and proportions requires the assistance of proteins; the greater variety of cells and cell types in multicellular organisms necessitates more kinds of proteins to keep them all in line.

3) Different types of cells require different types of proteins. If a unicellular organism needs a few certain proteins to keep itself running, those are the only ones it needs. But in a multicellular organism, different cell types may require different types of proteins to help them serve their function.