1. Bacteria

2. Prokaryotic! Bacteria are the ONLY prokaryotes on Earth!
Eukaryotic
Can be Both
Prokaryotic! Bacteria are the ONLY prokaryotes on Earth!

3. Remember! All Life Prokaryotic Bacteria Eukaryotic Fungi Protists
Plants
Animals

4. Prokaryotic vs. Eukaryotic Cells
Small & simple
NO NUCLEUS
No membrane-bound organelles
Larger & more complex
Contain a nucleus
Contain membrane-bound organelles

5. Unicellular! Bacteria are composed of a single cell!
Multicellular
Can be Both
Unicellular! Bacteria are composed of a single cell!

6. In what kingdoms can we find bacteria?
Protista
Fungi
Monera
None of the above
Bacteria can be found in the kingdoms Archaebacteria & Eubacteria!

7. Kingdom Archae-bacteria
All Life on Earth
Kingdom Eubacteria
Kingdom Animalia
Kingdom Plantae
Kingdom Fungi
Kingdom Protista
Kingdom Archae-bacteria

8. Archaebacteria vs. Eubacteria
Cell walls NOT made of peptidoglycan
Live in extreme environments
Cell walls made of peptidoglycan
Identified using gram staining
Prokaryotic
Unicellular

9. Structures of Bacterial Cells
Plasma Membrane: selectively permeable for exchange of nutrients and waste
Cytoplasm: fluid inside of the cell
Cell Wall

10. Structures of Bacterial Cells
DNA: free in the cytoplasm, but clustered in a “nucleoid region”
Flagella
Ribosomes

11. Structures of Bacterial Cells
Pili: small protein extensions used to anchor themselves OR to help exchange DNA with other bacteria

12. So how do we classify all these bacteria?
There are thousands of identified species of bacteria, but scientists have estimated that there are millions waiting to be discovered!
So how do we classify all these bacteria?
Bacteria are classified according to:
Shape
Cell Wall
Metabolism

13. What are some differences between the 2 types of bacteria shown here?
Shape!
Bacteria come in 3 shapes:
Round
Rod
Corkscrew

14. Classification by Shape
Coccus (cocci, pl.): round, can be found in clumps or lines
Baccillus (baccillis, pl.): rod shaped
Spirillum (spirilli, pl.): corkscrew (spiral) shaped

15. Spirillum
Coccus
Bacillus

16. Classification by Cell Wall
Eubacteria can be identified by the thickness of their cell wall.
Gram Staining determines how thick the cell wall is.
Gram + Bacteria: stains purple, have a thick cell wall
Gram - Bacteria: stains pink, have a thin cell wall
Gram Positive (+)
Gram Negative (-)

17. Gram +
Gram +
Gram –
Both
Neither
Bacillus anthracis

18. Gram -
Gram +
Gram –
Both
Neither
Spirillum volutans

19. Gram + and Gram - Gram + Gram – Both Neither
Staphylococcus aureus & Escherichia coli

20. A scientist uses gram staining on a colony of bacteria that she collected from a volcanic vent. What will her results be?
Gram +
Gram –
Both
Neither
Neither! The bacteria collected was archaebacteria. Gram staining will be ineffective, because archaebacteria do not have peptidoglycan in their cell walls. Gram staining can only be used to identify eubacteria!

21. Classification By Metabolism
Classified by how they obtain energy
Can be heterotrophic – obtains food from another source
Can be autotrophic – makes own food
Chemoautotrophs: make own food with inorganic molecules
Photoautotrophs: use photosynthesis

22. Where can we find bacteria?
What do you think the dirtiest part of the classroom is?
Your group will swab a location of your choice & see if bacteria are present.
We will check the growth in a few days.

23. Directions to Prepare the Petri Dish
Pre-Lab Questions
Write your group’s info on the bottom (initials of all of the members, & class period)
Agree on a location to test. Come to me for a sterile Q-tip.
Rub 1 side of the Q-tip on the location, then lightly rub the same side onto the agar.
Draw your dish on your handout.
Replace the lid & tape it shut.
Place it on the tray.