1. Kingdoms Archaebacteria & Eubacteria
(Formerly Monera)
Domains: Archae and Bacteria

2. They are found everywhere!
What are Bacteria?
Bacteria are PROKARYOTES
The smallest known living cells
Most are mm in size
They are found everywhere!
Bacteria on
head of a pin
Starr, 317
Did you know? There are over 80
species of bacteria in your mouth!
Bacteria in dental plaque
microbeworld.org

3. Some cause disease We call these “pathogens”
Anthrax, as seen by Koch
microbeworld.org
But most are
beneficial
Bacteria ferment cheese
Schraer, 641

4. Structure of Bacteria Most have a cell wall
Many have a capsule (jelly or slimy coating outside the cell wall, for protection)
They have a single, circular chromosome.
Some have plasmids (tiny rings of DNA separate from the chromosome.)
Cytoplasmic Pili help them talk to other cells.
Schraer, 632

5. Nucleoid

6. Many can MOVE, or go DORMANT
Some have flagella - made of
rope-like proteins, not
microtubules.
Some slide on a slimy secretion.
Many can form dormant
cells called endospores
to survive harsh conditions.
- tetanus, anthrax

7. Three basic shapes Spherical – coccus Rod – bacillus
Coiled - spirillum
Schraer, 633

8. Simple Colonies Staphylo = clusters Strepto = chains Diplo = double
Staphylococcus
wisc.edu
Diplo = double
Diplococcus
cat.cc.md.us
Streptobacillus

9. Asexual Reproduction Binary fission
Normal bacterial reproduction
1) chromosome replicates
2) copies separate as cell
wall lengthens
3) cell membrane pinches in
4) cells divide
Asexual Reproduction Binary fission
Steps in binary fission
maricopa.edu
Bacillus dividing by fission

10. Cell Respiration Most are obligate aerobes
Others are facultative or obligate anaerobes.
Anaerobes make a variety of fermentation products:
acids, alcohols, methane gas
food products

11. bacteria reproducing

12. See Fission in Action What stops them? They run out of food or space,
Did you know? In ideal conditions, some species can divide every 20 MINUTES.
What stops them?
They run out of food or space,
or wastes build up and poison them.

13. Sexual Reproduction conjugation
Two bacteria connect by a cytoplasmic bridge
Donor copies & passes DNA to recipient
Recipient now has new genes
Common way to transfer antibiotic resistance!!

14. Two more “sexual” reproductions
TRANSDUCTION
virus inserts DNA into bacterium
Prophage contains new genes
TRANSFORMATION
Bacterium takes in plasmids or DNA fragments from environment
Plasmids contain new genes

15. Sexual reproduction in bacteria

16. Two Kingdoms of Bacteria Differ in their chemistry
Kingdom Archaebacteria
- “Ancient”, most primitive
earliest known form of life -

17. Archaebacteria Differ chemically from Eubacteria
Eubacteria have cell walls with peptidoglycan
Archaebacteria have other polysaccharides
Ribosomes, lipids, enzymes are also different
Archaebacteria are more chemically like Eukaryotes – like us!
RNA polymerase enzyme

18. Archae are extremophiles
Live in habitats like early earth
Too harsh for most organisms
1) methanogens – decomposers,
live in animal intestines, swamps & bogs, sewage treatment
2) Halophiles – salt
3) Thermophiles – hot
4) Acidophiles – acid
Acidophiles – acid pools

19. Archaea are Extremophiles
Halophiles – Great Salt Lake, Dead Sea
Thermophiles – deep sea vents
Thermophiles – hot springs, geysers

20. Kingdom Eubacteria “Ordinary” bacteria Many decomposers
Some autotrophs
Nitrogen suppliers
Pathogens

21. Heterotrophic Bacteria
1) Nitrogen-fixing bacteria
a) “Fix” (change chemically) nitrogen gas from the air into a form plants can use
b)need nitrogen to make proteins, nucleic acids
c) live in soil and in legume plants
clover, peanuts,
soybeans, …
Legume roots – nodules contain
nitrogen-fixing bacteria

22. Decomposers Essential to nutrient cycling In soil Inside animals
Return inorganic chemicals to soil
Plants take up chemicals and make food
Some bacteria return nitrogen gas to the air
Inside animals
Enterobacteria – live inside us,
break down waste, make vitamins

23. E. Coli (enteric bacteria)

24. Photosynthetic bacteria
Cyanobacteria
Have chlorophyll a (green)
and cyanin (blue)
Most live in fresh water
Some in salt water,
soil and lichens
Starr, 315

25. Blue-green bacteria often link together, forming “filaments”

26. Blue-green bacteria are major producers in aquatic ecosystems

27. Some blue-green bacteria live with fungi in a symbiotic organism - lichen

28. Chemosynthetic Bacteria
Producers on ocean floor
Use heat and chemicals from thermal vents
Live inside giant tube worms

29. Human Uses for Bacteria
Food culture (yogurt, cheeses, vinegars)
Bioremediation (clean up poisons, oil spills)
Gene engineering
Source for antibiotics (ex. Streptomycin)
Water treatment
Drug development
Medical, genetic research

30. Pathogenic Bacteria
Many groups and types, but divided into two classes by GRAM STAIN
Schraer
637
Gram negative
Pink - Cell wall resists stain
Harder to treat if
pathogenic
Gram positive
Purple
Respond to normal
antibiotics

31. The Germ Theory of Disease 1800s
Louis Pasteur - microscopic organisms were the cause of many human diseases
Robert Koch - devised a set of steps to identify the organism responsible for an illness “Koch’s Postulates”
Joseph Lister – sterile technique

32. Some Bacterial Diseases
Salmonella tetanus diptheria
Strep throat tuberculosis MRSA

33. How do bacteria make us sick?
1) some make toxins that kill cells or interfere with their function
Botulism, salmonella, cholera
2) some kill cells directly
3) some reproduce so fast their numbers interfere with organ function

34. How Bacteria Populations Grow!!
Growth Curve (in Culture)
Schraer, 634
Why do they die out? Run out of food, or wastes build up

35. How do we fight bacteria?
Antimicrobial Agents - chemicals that inhibit bacterial growth
a) antiseptics – on living tissue (skin)
b) disinfectants – on nonliving surfaces
c) antibiotics – inside living organisms
- damage molecules needed when cells divide
- cell wall (penicillin); proteins (tetracycline)

36. What are prions?
Prions are misfolded protein molecules that can cause disease
- no DNA (not a virus)
- they induce normal proteins to misfold
- cause loss of tissue/organ function death
- ex. “Mad Cow Disease” (brain)
- Creutzchfeldt-Jakob Syndrome in humans
- get it from eating contaminated meat

37. What are viroids? Circular pieces of RNA
No protein or membrane coat (not a virus)
Can cause disease, more often in plants
Only human example – hepatitis D

38. A misfolded protein

39. Little is Better!! Most prokaryotes measure 0.5-1.0 mm
Metabolism is FAST
Bacteria can absorb nutrients and secrete wastes rapidly because of high
surface-to-volume ratio
Did you know? Lactose fermenters break down 10,000 times their weight in lactose in an HOUR!

40. Kingdom Archaebacteria
Why a separate kingdom?
Archae differ chemically from other bacteria.
1) cell wall - different amino acids and sugars.
Eubacteria have peptidoglycan
Archaebacteria have varied polysaccharides
but not peptidoglycan.
2) membrane lipids
3) ribosomes
4) enzymes >
5) cytochromes
6) gene sequences And MORE
RNA polymerase

41. - colors range from pink to black - photosynthesize without water
More photosynthetics
2) green-sulfur and purple bacteria
- anaerobic
- colors range from pink to black
- photosynthesize without water
- make no oxygen
- live in pond and sea mud

42. Nutrition Most are heterotrophs - saprobes or parasites
Some are Autotrophs
-photosynthetic or chemosynthetic
Did you know? Chemosynthetic bacteria are the base of the food chain at ocean floor vents.

43. Sources
Schraer and Stoltz, Biology, the Study of Life, 7th ed. Prentice-Hall, 1999
Starr, Cecie, Biology, Concepts and Application, Wadsworth Group, 2003
Fission
Archaebacteria
Staphylococcus
Conjugation
Legume nodules
Salmonella
Bacteria reproducing
Dental plaque
Fission time-lapse
Diplococcus