1. Prokaryotes Chapter 27 – Campbell & Reese 7 th edition blog.thesietch.org © Leonard Eisenberg, evogeneao.com/tree.html

2. Prokaryotes – Common Physiology What important characteristics are common to all prokaryotes? -single cell -no nucleus -single circular chromosome -no organelles, simpler ribosomes -smaller size than Eukarya, characteristic shapes -cell wall © McGraw Hill Companies © K.G. Murti/Visuals Unlimited phs.d211.org activity.ntsec.gov.tw

3. Prokaryotes – Common Physiology Other important features common in many prokaryotes? -Flagella -Fimbriae -Capsule -Plasmid ring(s) of DNA © Pearson Education National Science Foundation www.bio.miami.edu/~cmallery/© Cell Graphics

4. Archaea vs. Bacteria Archaea are, somewhat, prokaryotes that do not fit into bacteria -no nuclear membrane -no organelles -circular chromosome They share some of the characteristics of Eukarya (and represent a clade more recently diverged from the eukaryotic ancestor than Bacteria) -multiple RNA polymerases (transcription/translation machinery more similar to Eukarya) -some introns -histones -methionine initiator codon The domain also has many generally unique characteristics -extremophiles -membrane lipids with ether bonding from fatty acid to glycerol -metabolism: nitrogen fixation, denitrification, methanogenesis -Still many unknowns, a predicted majority of species of Archaea, as well as Bacteria, on Earth have still not been discovered and studied

5. Systematics Through History Ernst Haeckel (1834-1919) and his geneological Tree of Life

6. Systematics Now – Tree based on genomic similarity (Lee, Robinson & Marx 2011) Archaea Bacteria

7. Prokaryotes – Energy/Carbon Sources and Ecological Roles -photoautotrophs, ex: Cyanobacteria -chemoautotrophs, ex: sulfur oxidizer -heterotrophs -parasites, ex: many Spirochaetes -(photoheterotrophs) -Obligate aerobe vs. anaerobe obsessedwithreality.wordpress.com tolweb.org www.photolib.noaa.gov

8. Symbiotic Bacteria -nitrogen cycle -nitrogen fixation -nitrifying bacteria -denitrifying bacteria -global warming -methane consumption -ruminants lamar.colostate.edu ehow.com

9. Prokaryotes - Reproduction -Binary Fission, daughter clones except due to mutation -Endospores, survival in adverse environments -rapid generational turnover, E. Coli optimally reproduce every 20-30 min -Lenski Long-Term study, First controlled study of Natural E. Coli evolution 50K+ generations © ASM MicrobeLibrary.org emc.maricopa.edu

10. Prokaryotes – Horizontal Gene Transfer Mechanisms Transformation Take in naked DNA from surroundings Some species do this naturally, others can be coerced in lab Transduction Gene exchange mediated by phage/virus Phage genome integrates into bacteria’s and is improperly excised, taking bacterial gene(s) with it to another host Conjugation Direct cell to cell transfer, usually by a connecting pilus Plasmids especially conferring antibiotic resistance Other: transposons, homologous recombination, phage integration microbiologyonline.org.uk

11. Research – Does the biological species definition apply for all prokaryotes?

12. Prokaryotes – Common Physiology What important characteristics are common to all prokaryotes? -single cell -no nucleus -single circular chromosome -no organelles, simpler ribosomes -smaller size than Eukarya, characteristic shapes -cell wall © McGraw Hill Companies © K.G. Murti/Visuals Unlimited phs.d211.org activity.ntsec.gov.tw