Ever heard the cliché, no two humans are alike? Guess what, no two cells are alike either. I know, crazy! But lets just think about what a cell actually is. Maybe we can understand this as what is a cell supposed to do – yuck, a philosophical question. Perhaps then – how does it work? Mmm ok that is starting to sound better. Well boiling it down they take in energy and will do something. What is that special something? Sex. Well not quite, I would say replication to be more precise. Essentially, a cells most basic function is to make more cells. So then lets explore the question. Do prokaryotic cells differ from eukaryotic cells?
Take me back to year 11 biology textbook
- Know what a prokaryotic cell is and define it as a cell without a nucleus
- Know what a eukaryotic cell is and define it as a cell with a nucleus
So I lied. I said all cells are different. But. Here it is. All cells do have some things in common. They all have a separation between themselves and the environment. This is known as a cell membrane. The cell membrane just keeps everything that meant to be inside the cell, inside the cell. Anything that should be outside the cell, you guessed it, outside the cell. It is like the bouncer at the club, it will selectively let in what it wants to let in. The cell juice is also a common feature to all cells. The cell juice is a sort of fluid which has critical chemicals for the cell dissolved in it. Biologists like to sound smart so they call the cell juice, the cytoplasm. Finally, the other thing thing all cells have are ribosomes. These are just like little workers within the bounds of the cell. Their job is to build the stuff the cell needs.
Yeah sick, but what’s a prokaryotic cell? Essentially, a prokaryotic cell is a cell where the instruction manual isn’t kept separate from every other part of the cell. Instead of storing the genetic information, the DNA, in a nucleus. The prokaryotic cell will just let it float around in the cell juice, the cytoplasm. An example you would know of a prokaryotic cell is bacteria – think salmonella from off chicken. Or perhaps you know of Archae which are little cells which are like the elite army units able to withstand extreme temperatures and harsh conditions. It’s a Greek word, prokaryote, Pro (before) and Karyon (nuceleus). This is because prokaryotic cells evolved before eukaryotic cells and before the latest update of a nucleus.
Wait. What? A eukaryotic cell is a what? It is a cell that has a nucleus. This means it keeps the genetic information, the blueprints for the cell, inside a capsule. Remember before our bouncer – the cell membrane – well a eukaryotic cell has the stuff inside it also guarded with cell membranes. Yeah. Yeah. The Greeks one and got to name the eukaryotic cells as well. Eu is (true) and karyon is (nucleus). So Eukaryotic cells contain a nucleus and other ‘things’ which are bound by membranes.
All living things are made from cells. Hopefully you knew that. A living thing such as a bacterium is made from one cell. To sound cleaver we call it unicellular. While large living things such as humans are made from lots of cells which work together. Wowza, we call humans, dogs, plants, anything with more then one cell a multicellular organism.
However, this classification system wasn’t enough for biologists. So they had to come up with this idea of prokaryotic vs eukaryotic cells. The reason being, there are some complex organisms made with just one cell.
Bacteria evolved first on earth, they are extremely simple and as such they didn’t need a nucleus to store their genetic information – we call them prokaryotic cells for this reason. From bacteria evolved more complex organisms, both unicellular and multicellular. These did require a nucleus to store their more complex genetic information. We call these organism eukaryotic.
Here’s what you need to know.
Prokaryotic cells differ from eukaryotic cells – exam-style questions
Briefly explain whether the following statements are correct?
a) Bacteria are the only cells that require a nucleus [1 mark]
b) All single celled organisms are prokaryotic [1 mark]
Compare and contrast prokaryotic and eukaryotic organisms. [4 marks]
Evaluate the benefits for an organism being eukaryotic over prokaryotic. [3 marks]
Divergent Thinking Question.
Why do you think there are still prokaryotic cells around today if eukaryotic cells evolved from prokaryotic cells?
Answers for Exam-style Questions.
a) False: bacteria are prokaryotic.
b) False: There are single celled eukaryotic organisms such as yeast cells.
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About the author
Joshua Mills has a bachelor of Adv Science (medical science and medicinal chemistry) from USYD. He founded Edzion.com in 2019 – an online complimentary education company to support and inspire high school science students. Currently he’s undertaking higher degree research, using the virus’ that infect bacteria as a search engine to develop a therapeutic to treat children’s bone cancer. In his spare time, he runs ultra-marathons.
Biology HSC year 11 Free interactive textbook