1. 1 Review In what ways do prokaryotes differ from one another Evaluate Use pg 486. Which category of prokaryote is the most flexible in the energy sources it can use- explain 2 Review List three ecological roles played by prokaryotes Explain Why are nitrogen fixing bacteria so important

2. Ch 20 Viruses and Prokaryotes

3. Classifying Prokaryotes
Unicellular organisms that lack a nucleus
Has DNA, but it is not found in a membrane- bound nuclear envelope.

4. Prokaryotes are classified as Bacteria or Archaea
Two of the three domains of life.

5. Bacteria Larger of the two groups Do not agree exactly how many phyla
Live almost everywhere.

6. Surrounded by a cell wall that protects the cell from injury and determines its shape
Contains peptidoglycan
Some have flagella
Pili
Serve mainly to anchor the bacterium to a surface or to other bacteria.

7. Archaea Look very similar to bacteria But
Walls of archaea lack peptidoglycan
Membranes contain different lipids
DNA sequences of key archaea genes are more like those of eukaryotes than those of bacteria
Live in extremely harsh environments.

8. Three Archae Varieties
Thermoacidophiles
Live in hot and acid environments such as hot springs and coal debris, still keep internal pH around 7.

9. Three Archae Varieties
2. Halophiles
Live in high salt concentrations
Ocean borders, great salt lake, dead sea.

10. Three Archae Varieties
3. Methanogens
Produce methane
Anaerobic
Live in thick mud and the digestive tracts of animals.

11. Size, Shape, and Movement
Bacilli
Rod-shaped prokaryotes.
Cocci
Spherical prokaryotes.
Spirilla
Spiral and corkscrew-shaped prokaryotes
Also be distinguished by whether they move and how they move
1-5 micrometers.

12. Nutrition and Metabolism
Store energy as sugars
Energy is released during cellular respiration, fermentation, or both.

13. Energy Capture
Page 486.

14. Energy Release
Page 487.

15. Growth and Reproduction
Binary fission
Replicates its DNA and divides in half, producing two identical cells
Asexual
Does not involve the exchange or recombination of genetic information
With optimal conditions can replicate every 20 minutes
Endospore
Thick internal wall that encloses the DNA and a portion of the cytoplasm during unfavorable conditions.

16. Mutation Mutations are one of the main ways prokaryotes evolve
Mutations are inherited by daughter cells produced by binary fission.

17. Conjugation Exchange of genetic information in prokaryotes
Hollow bridge forms between two bacterial cells
Genetic material, usually a plasmid, moves from one cell to the other.

18. The Importance of Prokaryotes
Essential in maintaining every aspect of the ecological balance of the living world.

19. Decomposers Decompose complex organic molecules into simpler molecules
Supply raw materials
Treat industrial sewage
Purify water
Produce fertilizer.

20. Producers Among the most important producers
Many food chains dependant on them.

21. Nitrogen Fixers
Nitrogen in atmosphere is not useable by the majority of species
Nitrogen-fixing bacteria and archaea provide 90 percent of the nitrogen used by other organisms
Legumes
Symbiotic relationship between plants and nitrogen fixing bacteria that live in nodules in the plant’s roots.

22. Human Uses of Prokaryotes
Yogurt, sauerkraut, and buttermilk
Digest petroleum and remove human-made waste from water
Synthesize drugs and chemicals.