1. 2.2 Bacteria

2. Basics: Unicellular (single celled) No nuclear membrane
Small (less than 2 um)
Only 1 circular chromosome

3. Classifying bacteria:
To classify bacteria, you analyze:
Cell shape
Cell wall
Movement
Type of respiration
Metabolism
Reproduction

4. Morphology / Shapes There are three common shapes of prokaryotes:
1) spherical (singular: coccus, plural: cocci)
2) rod (s. bacillus, p. Bacilli)
3) spiral (spirillium)

5. Morphology continued…
When these bacteria cells aggregate, they can form “groups”
1) Mono = one
2) Diplo = two
3) Strepto = in a chain
4) Staphlo = cluster
Ex. Steptobacilli?
Staphylococci

6. Cell Wall (pg 64)
We classify bacteria as gram positive or gram negative when analyzing cell walls
We use a combination of crystal violet and iodine to STAIN a sample of bacteria
If the cell wall is THICK, it usually has a THICK peptidoglycan layer. This layer will get STAINED (purple) gram positive bacteria
If the cell wall has a very thin peptidoglycan layer (pale pink) gram negative bacteria

8. Why does the cell wall matter?
The composition of the cell wall is unique to the strain of bacteria
Antibiotics target cell walls
If we can identify the composition, we can create specific antibiotics to target certain strains of bacteria!
Certain antibiotics prevent the cell wall from forming. As pressure builds in the cell, without the cell wall the bacteria bursts and dies.

9. Movement There are three main structures for movement:
Flagellum – tail like structure that whips around to propel the bacteria
Cilia – small hair-like projections surrounding the cell that help it to “swim” back and forth
Non-motile – sticky cilia like structures that keep the bacteria from moving

10. Type of Respiration Aerobic – grows in the presence of oxygen
Anaerobic – grows in the absence of oxygen
Obligate aerobes –MUST have oxygen
Obligate anaerobes
Facultative anaerobes – can grow with OR without oxygen

11. Metabolism
Autotrophs
Heterotrophs
Chemotrophs

12. Autotrophs
Make their own energy source by using solar energy and converting it into chemical potential energy
Ex. Cyanobacteria (blue green algae)– uses photosynthesis to make glucose

13. Heterotrophs Obtain energy from eating other organisms
Ex. E.coli - find an example of what they eat!

14. Chemotrophs
Make their own energy from chemicals like sulfur or hydrogen sulfide
Ex. Methanogen – lives in deep sea vents

15. EXTREME types Halophiles – LOVES salt (i.e. lives in oceans)
Thermophiles – LOVES hot (ie. Lives in hot springs)
Psychrophiles – LOVES cold (i.e. lives in arctic soils)

16. Reproduction Binary Fission (asexual) Conjugation (sexual)
Endospore Formation (dormant)

17. Binary Fission
When bacteria copies it genetic information, then splits into two identical daughter cells
Refer to pg 62 and draw the diagram

18. Conjugation
The donor cell attaches itself to the recipient cell via a pilus
The donor cell donates a copy of a plasmid (circular, small DNA)
A common trait / info that is passed between bacteria through conjugation is resistance to antibiotics like penicillin or ampicillin

19. Conjugation

20. Endospores
When environmental conditions threaten survival, some bacteria can form endospores
They are hard-walled structures that protect and store the bacterial DNA/RNA
The hard walls are resistant to temperature, dehydration, radiation and toxic chemicals!
They can survive from weeks to thousands of years!

21. Homework:
Go to wiki and watch the videos posted for bacteria – make notes
Read pg 65
Pg. 66 # 2-8