Advanced Biology Prokaryotes

1. Advanced BiologyProkaryotes Chapter 28

2. The first cells (28.1) • Isotopic Data • Carbon-12 is found in microfossils • This is used for carbon dating of organisms and carbon fixation • Pathways include: • Calvin Cycle (photosynthesis) • Krebs Cycle (cellular respiration) • Hydrocarbons • biomarkers • The Earth formed approximately 4.5 billion years ago • The first fossil formations found on Earth are dated to 3.5 billion years ago • Microfossils • Fossil form of microscopic organisms

3. Prokaryotic Diversity (28.2) • Prokaryotes are the oldest form of life. • They have a simple structure and • They are also the most abundant form of life on Earth • Cyanobacteria (photosynthetic) changed Earth’s atmosphere to be able to produce oxygen • Abundant amounts of prokaryotes – ~10% identified • New techniques to identify w/o culturing • Two groups: • Archae and Eubacteria

4. Prokaryotes can live anywhere • Found in deep sea caves, volcano rims and inside glacier formations • Some Archae are extremophiles – extreme environments such as hot springs, geysers, toxic gases and extreme cold (Anartica) • Extremes may indicate earth’s conditions 3.5 bya

5. Prokaryote vs. eukaryote Prokaryotes Eukaryotes Unicellular and multicellular Cell size – normally ≥10ųm Membrane bound nucleus Mitosis – sexual Genetic Diversity via Mutations Membrane bound organelles Flagella and cilia w/microtubules – whiplike Photosynthesis release oxygen • Unicellular • Cell size – vary • ≤1ųm up to 750 ųm • Single circular chromosome • Plasmids • Binary Fission – asexual • Horizontal gene transfer • No internal compartments – ribosomes differ • Flagella – single fiber – spin • Oxygenic and anoxygenic • chemolithitrophic

6. Prokaryotes • Eukaryotes

7. Archae vs. eubacteria • Plasma membrane in both but differs in glycerol link to hydrocarbon chains • Cell Wall– Peptiglycan in Eubacteria but not in Archae • DNA Replication differs by place of origin and proteins • Gene Expression – Archae may have more than one RNA polymerase

10. Classification • Classification of prokaryotes were gram staining and observations such as: • Can photosynthesize • Mobility • Unicellular or colonies • Spores or binary fission • Whether it is pathogenic • Now classified by evolutionary means using DNA analysis

11. Prokaryote cell structure (28.3) • Three basic forms: • Rod shaped (bacillus) • Sperical shaped (coccus) • Spiral shaped (spirillum or spirochetes)

12. Cell structure • Cell wall determines cell shape • Lack cell wall, no particular cell shape • Flagella • Chains • Colonies • Branching filaments

13. Cell Wall • Cell wall basically contains peptidoglycan with a polymer that forms a strand of crosslinked polysaccharides with peptide chains • Archae may have pseudomurein or pseudopeptidoglycan

14. Gram staining Gram + will stain purple Thick Peptioglycanso traps crystal violet Gram – will stain pink Multiple layers does not trap crystal violet but will show the red dye

15. Other Stuctures • Capsule • Gel type outer layer • Allows for adherance and evasion from immune system • Flagella • Structure that allows movement connected at cell wall and spins – made of protein flagellin

16. Pili • Hairlike structure that allows movement (gram-), attachment and exchange of genetic information

17. Endospores • Dormant stage in prokaryotes • Thick wall formed when environmental stress • Stay dormant for days to centuries • Examples: Tetanusor anthrax

18. Internal structures • Ribosomes • Smaller than Eukaryote ribosomes • Different proteins and RNA • Antibiotics will bind to these ribosomes blocking protein synthesis • Internal membranes • Respiratory membranes – photosynthesis • Nucleoid • Double stranded circular DNA (nucleoid region) • Plasmid – replicating circular DNA (small)

19. Prokaryotic genetics (28.4) • CONJUGATION • Prokaryotes reproduce asexually • Exchange DNA through • Conjugation - transfer plasmids (F+/F- ) • Transduction • transformation

20. Transduction • DNA transfer from one bacterium to another via a virus

21. Transformation (Griffith) – Cell death causes lysis that releases fragments of DNA into the environment where another bacteria incorporates it into its genetic material

22. Antibiotic resistance and Mutations • Due to its rapid reproduction a mutation in a bacterium can spread rapidly • Media growth (Nutrient Agar) • Auxotroph – need supplement • MRSA and VRSA • Plasmids can have resistant genes incorporated • E.coli found in digestive tract of humans vulnerable

23. Prokaryotic Metabolism (28.5) • Photoautotrophs – sunlight to build from carbon dioxide • Chemolithoautotrophs – oxidize inorganic substances such as ammonia to nitrite • Photoheterotrophs – Sunlight for energy and other molecules for carbon • Chemohetertrophs – carbon and energy from other molecules • Intake of energy and carbon – 4 Ways: • Photoautotrophs • Chemolithoautotrophs • Photoheterotrophs • Chemoheterotrophs

24. Human Bacterial disease • See Table 28.1 on page 561. • Infective diseases by bacteria killed over 20% of US children before age 5 before the discovery of antibiotics by Pasteur and Koch • Bacteria can infect by various methods such as droplets in air, feces or pests

25. Beneficial prokaryotes • Symbiotic relationships • Mutualism – nitrogen fixation or digestion • Commensalism - live outside of organism without harming • Parasitism - infection • Prokaryotes can cause harm but there are some that are beneficial • Bacterial decomposers along with fungi put C, N,P, S back into the soil • Fixation during nutrient cycling of carbon and nitrogen

26. Genetic Engineering • Human genes can be inserted into bacterium to produce human proteins such as insulin • Biofactories for enzymes, vitamins, antibiotics and industrial compounds • Bioremediation • Removing pollutants from water, air and/or soil • Bacterium used in wastewater treatment plants to breakdown raw sewage. • Future development in removing toxic waste