1. Prokaryotic & Eukaryotic Cells

2. As you have already learned, everything is made up of living cells.
And the cells themselves are made up of many different parts .
There are many different cells that do many different things, but all of these cells fall into one of the two main categories:
Prokaryotic cells & Eukaryotic cells

3. What the words mean Prokaryotes Eukaryotes Pro = before
Karyose = kernel, which represents the nucleus
So prokaryotes occurred before cells with a nucleus
Ex. Bacteria
Eu = true
Karyose = kernel, the nucleus
So eukaryotes are the cells with a true nucleus
Ex. Found in animals, plants, and fungi (yeast)

4. What they have in common
DNA
Cell (plasma) membrane
Ribosomes
Simple in Prokaryotic, complex in Eukaryotic
Cytoplasm
Allow the flow of nutrients and wastes to enter and leave the cell
Have similar metabolic ( life processes) like photosynthesis and respiration
Require a supply of energy
Made from the same basic chemicals
Carbohydrates, proteins, nucleic acid, fats, minerals, and vitamins

5. Differences
That’s what they have in common, but there are significant differences too.
The two main ones are age and structure.

6. Age Differences
Scientists believe that prokaryotic cells (in the form of bacteria) were the first life forms on earth. They are considered “primative” and originated 3.5 billion years ago. That is 2 billion years before eukaryotic cells and billions of years before our earliest ancestor, the hominids.
4.6 billion years ago – Earth was formed
3.5 billion years ago – the first life arose: prokaryotic bacteria
1.5 billion years ago – eukaryotic cells arose
500 million years ago – multi-celled eukaryotes arose
3 million years ago – our earliest ancestor, the hominids, appeared
Read the passage and tell students to write down the age of prokaryotes and eukaryotes.

7. Structural Differences
Eukaryotic cells contain two important things that prokaryotic cells do not:
A nucleus
Membrane bound organelles
Tell them to write this in their notes.

8. DNA Although both contain DNA:
The DNA in eukaryotic cells in in the membrane bound nucleus
The DNA in prokaryotic cells floats around in the cell in what we call a
Nucleoid – not a real structure, just a word to describe the inside of the cell where the nuclear material sits
Read and tell them to write down the differences between the two types of DNA in cells.

9. Organelles
The organelles in eukaryotic cells allow them to perform more complex functions than prokaryotic cells.
Prokaryotic cells do not have organelles like eukaryotic cells.
Both have ribosomes, but they are much more complex in Eukaryotic cells.
They do not need to write any of this, just read it to them and point out the nucleoid in the prokaryotic cell. Also point out the ribosomes in both and how the eukaryotic cell has many more organelles.

10. Chloroplasts and mitochondria
Evidence suggests that chloroplasts and mitochondria were once bacteria that developed a symbiotic relationship with cells that have a nucleus
Chloroplasts and mitochondria have their own DNA that is not a part of the cells.
Yes, plants have both chloroplasts and mitochondria.
Just for fun info. Tell them to read it.

11. Size
Eukaryotic cells are about 10 times larger than prokaryotic cells.
Have them write this in their venn diagram.

12. Cell Wall
Both have a cell wall, but they may be made up of different substances.
Have them write this in their venn diagram.

13. Flagella & Cilia
Flagella and cilia are the structures that help cells move.
Eukaryotic flagella are more complex than prokaryotic flagella.
Point out the structures on the overhead. Also, tell them that not all eukaryotic cells will have these structures, but some do. AND that prokaryotic cells may have one or the other or both.

14. Check for Understanding
Eukaryotic and Prokaryotic Cell Structure
Cell Structure
Prokaryotic Cell
Typical Animal Eukaryotic Cell
Cell Membrane
Yes
Cell Wall No
Cilia or Flagella
Yes, simple
Yes, complex
Endoplasmic Reticulum
Golgi Complex
Lysosomes
Mitochondria
Nucleus
Ribosomes
Have them participate in a thumbs up, thumbs down activity. Tell students that you will say the organelle and if the prokaryotic cell has it they should give you a thumbs up. If the cell does not have it they should give you a thumbs down. Tell students they can reference their notes if they are not sure.

15. New Discoveries
Until recently, it was thought that only eukaryotic cells existed in multi-celled groups like in organs and tissue. Recent discoveries suggest that some prokaryotic cells do too.
This is just one more example of how new discoveries are always changing what we know – or think we know.
But that is what makes science so exciting!
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