1. BIOLOGY 304F EVOLUTION OF PLANTS Fall 2008 Lecture 4 Thursday September 25, 2008 Chapter 13, Prokaryotes and Viruses

2. Microbiology in One Lecture Whole courses at UWO on prokaryotes and viruses, or even groups of them or their physiology, ecology or impacts (e.g., microbial ecology, human diseases) – we will cover them today as part of the evolution leading to plants. Text covers them well at an appropriate level in just 25 pp. Be sure to know the “Checkpoints” (1 st page) and “Summary” plus “Selected Key Terms” (last 3 pages).

3. Some statistics: 3000 or so described species of prokaryotes (all treated under the Bacterial Code) In the open ocean, make up 90% total biomass On land, there may be in the order of 1-10 x 10 9 cells per gram dry weight of soil, and these may represent 4000 or more “species” based on DNA re-association experiments. 1 x 10 10 to 10 12 cells per gram in your guts!

4. Bacterial Origins Oldest known fossils are 3.5 BYA, suspected to be ancient cyanobacteria, but possibly not; first forms were almost undoubtedly heterotrophs, not autotrophs. Arguments now about whether first cells developed in super-hot environments such as hot springs or deep-sea thermal vents at 90- 100+ C, or in more moderate conditions at the edges of seas or lakes. Archaea are probably not the oldest group, despite their name.

5. Bacterial Evolution Review tree of life and a Woese tree

7. Bacterial Structure and Parts Review bacterial cell structure, and cell walls of Gram+ and G- Not all bacteria have flagella (vs. subheading p. 284) Fimbriae and sex pili, endospores

10. Ancestral Cyanobacterium Ancestral Purple Non-Sulfur Bacterium

11. Bacterial Shapes and Terms Rods, cocci, spirilla and filamentous [many, but by no means all, human pathogens are cocci, whereas nearly all plant paths are G- rods] aerobes and anaerobes thermophiles, psychrophiles, halophiles; extreme, facultative and obligate

13. Bacteria are Not all Single-Celled There are colonial bacteria in a true sense – cooperation among individuals in a colony; and many “single-celled” forms have colonial communication such as quorum-sensing and chemotaxis.

14. Methods of Genetic Recombination in Bacteria Conjugation via pilus (pl. pili) transformation [DNA outside of cells is frequently stabilized for years to centuries by adsorption to soil colloids or organic compounds; however, this also is the basis for “cloning”] transduction [also used as a technique in cloning to get desired DNA into a cell]

15. Selected Groups of Bacteria, and their Importance* 1.Cyanobacteria Fall within G+ group, have chlorophyll a, carotenoids, and two phycobilins: phycocyanin and phycoerythrin (bluish and reddish); heterocysts (N2-fixation) and akinetes (resistant “spores”); possible endosymbiont of red algal chloroplasts

16. Bacterial Groups II 2.Actinomycetes Filamentous Gram+; abundant in soil; odour of fresh soil = geosmin; some cause plant diseases, many very important in producing antibiotics, including ant- associates; Frankia is a root-associate with many boreal shrubs, N 2 -fixing;

17. Bacterial Groups III 3.Purple and Green Bacteria Photosynthesis without evolution of O2! Strict anaerobes. Some use sulfur (see formula for photosynthesis reaction in PSB), others use organic compounds as electron donors. Ancestor or relative of PNSB thought to be origin of mitochondria; P&GBs have photosystems that appear ancestral to exisiting photosystems I and II in green plants.

18. Bacterial Groups IV 4. Proteobacteria – majority of well-known G- rods (Pseudomonas, Escherichia) 5.And many others …

19. ARCHAEA 1.Extreme halophiles (heterotrophs and a few are photoheterotrophs: Halabacterium, using bacteriorhodopsin as light receptor) 2.Extreme thermophiles (mostly anaerobes, many also chemoautotrophs) 3.Methanogens (moderate, but anaerobic environments; generate CH 4 fromH 2 and CO 2 - chemoautotrophs)

20. VIRUSES Nucleic acid (ds or ss DNA or RNA – i.e., 4 main types) surrounded by a protein capsid Those that attack bacteria are called bacteriophages or just phages Submicroscopic – can’t usually be seen with light microscope at 1000x Main shapes are rods, bullets, polyhedrons, filaments Replicate using the host machinery, either by incorporation into genomic DNA or piracy of it from outside

21. Viruses Viruses are non-living entities according to most definitions of life (e.g., being composed of cells; reproducing and metabolizing by themselves) and since they are (now) dependent on other organisms must (?) logically have come after the first true life, which appears to have been prokaryotes.

22. Viroids & Prions VIROIDS are infectious ssRNA PRIONS are infectious proteins (Mad Cow, etc.)