1. Prokaryotes vs. Eukaryotes
KEY CONCEPT Simple cells are called prokaryotes, complex cells are called eukaryotes.
Leukocyte (white blood cell) & Bacteria
False Color Scanning Electron Micrograph;
Magnification 11,000x)

2. Prokaryotes vs. Eukaryotes
All cells share certain characteristics.
Can you identify the organelles in this photo?
Most cells are microscopic.
All cells are enclosed by a membrane.
All cells are filled with cytoplasm.
All cells use energy and reproduce using DNA.
Answers on another slide!
Bacterium
(false colored Transmission Electron Micrograph;
magnification 19,0000x)
cytoplasm
cell membrane
Relative size compared to eukaryote!

3. Prokaryotes vs. Eukaryotes
There are two cell types: eukaryotic cells (“true nucleus”) and prokaryotic cells (“before nucleus”).
All bacteria plus blue-green algae are prokaryotes.
All animals, plants, fungi, most algae, and complex unicellular organisms called protists are eukaryotes.
Amoeba
Bacillus Bacteria
Blue-Green Algae
Prokaryotes
Eukaryotes

4. Prokaryotes vs. Eukaryotes
Prokaryotic cells are usually much smaller than eukaryotic cells.
These red bacteria are about the size of one mitochondrion inside the white blood cell!!

5. Prokaryotes vs. Eukaryotes
Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells.
Eukaryotic cells have a nucleus with their DNA inside.
Prokaryotic cells do not have a nucleus – their DNA is floating in the cytoplasm.
nucleus
Golgi godies
centrioles
vacuoles
mitochondria
cell membrane

6. Prokaryotes vs. Eukaryotes
Prokaryotic DNA is organized differently than eukaryotic DNA.
Prokaryotic cells have DNA in one large piece, plus several small rings of DNA called plasmids.
Eukaryotic cells have DNA broken in sections called chromosomes (when wound up tight like a ball of string) or chromatin (when loose and ready for use).
Bacterial DNA & Plasmids
One Human
Chromosome
(Out of 46)

7. Prokaryotes vs. Eukaryotes
Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells.
Prokaryotic cells have some organelles (like ribosomes & cytoskeleton), but none of them are covered with membranes.
Eukaryotes have both organelles with membranes and organelles without membranes, such as mitochondria, chloroplasts, vacuoles, er, ribosomes, cytoskeleton, and more.
nucleus
“membrane-bound organelles”
cell membrane

8. Prokaryotes vs. Eukaryotes
Prokaryotic cells conduct all the same functions as eukaryotic cells.
Prokaryotic cell functions occur all together, since there are no membranes separating the cytoplasm into different areas. But they still can conduct photosynthesis, respiration, reproduction, and more.
Eukaryotic organelles divide the cytoplasm into regions with specialized functions including photosynthesis, respiration, reproduction, and more.

9. Prokaryotes vs. Eukaryotes
Simple prokaryotic cells evolved long before complex eukaryotic cells.
Fossils of prokaryotic cells have been found in rocks as old as 3.5 billion years old.
The oldest eukaryotic fossil cells are about 1.5 billion years old.
PS: Special saws can slice rock into sections that are thin enough to look at with a microscope!
Photo of
Fossil Eukaryote
Photos & Drawings of
Fossil Prokaryotes