Prokaryotes

1. Prokaryotes

2. Prokaryotes • Classification of prokaryotes has dramatically changed due to analysis of the genomes of various types of cells: • The description of these organisms as members of Kingdom Monera, has been abandoned and replaced with a three domain system. These Domains are as follows: • Domain Bacteria (Eubacteria) • Domain Archaea • Domain Eukarya • The domains bacteria and archaea contain the prokaryotic organisms. • Domain Eukarya include the protists and the other multicellular kingdoms.

3. Found in nearly all prokaryotes; structure differs in gram+ and gram- bacteria Hairlike appendages that help cells adhere to other cells or a substrate Often accompanied by smaller rings of DNA called plasmids Sticky layer of polysaccharide or protein that can help cell adherence and/or evasion of a host’s immune system Appendage that facilitates conjugation There are also lots of Ribosomes and Enzymes found in the cytoplasm of bacterial cells No nucleus or other membrane-bound organelles; usually no complex compartmentalization Organs used by most motile bacteria for propulsion; many species can move toward/away from certain stimuli

4. Eubacteria General Characteristics • Bacteria are the smallest "living" organisms • Are prokaryotic cells • Lack Nucleus • DNA is naked. - a single loop - not bound into a chromosome. • May contain plasmids (small circular fragments of DNA) • Lack membrane-bound organelles • Usually have an outer Cell Wall. • Act as decomposers in ecosystems • NO INTRONS • How are genes that work together in performing a task arranged in the circular “chromosome”? • Think “Slack & Trip”

5. Eubacteria General Characteristics • EUbacteria have peptidoglycan in cell walls • Sometimes have an Outer Capsule - These stain red in a Gram Stain test and are called Gram Negative bacteria. • Those without an outer capsule stain blue in the gram stain test and are called Gram Positive Bacteria http://www.cellsalive.com/cells/bactcell.htm

6. BACTERIAL CLASSIFICATION: • Bacteria are classified generally by 3 characteristics • The bacterial cell shape • The bacterial cell arrangements • Ability to accept a Gram stain

7. Bacterial Shape: • Bacteria have 4 basic shapes: • Rod-shaped – bacilli • Bent rod shaped - Vibrios • Spherical - cocci • Spiral – spirilli

8. Bacterial Arrangement: • Bacteria have 3 basic arrangements: • Occurring singly = “Mono” arrangement • Occurring in pairs = “Diplo” arrangement • Occurring in clusters = “Staphlo” arrangement • Occurring in long chains = “Strepto” arrangement streptococcal pharyngitis

9. Gram Staining: • Bacteria can be categorized by their ability to accept a gram stain. • Bacteria are exposed to several staining agents; Crystal Violet, Gram’s Iodine, and safranine (altogether Gram stain). • If the bacteria possesses a cell capsule, it will retain a pink color. This is referred as to a “Gram Negative” bacteria • If the bacteria lacks a cell capsule it will retain a blue color. This is referred to as a “Gram Positive” bacteria Gram Negative Bacteria Gram Positive Bacteria

10. How Bacteria obtain energy: • Two major categories: • Autotrophs - Make their own energy - 2 types • Photoautotrophs - Get energy from sunlight (cyanobacteria, plants, & algae) • Chemoautotrophs - Get energy from inorganic molecules through oxidation (eg. Sulfides used by certain prokaryotes) • Heterotrophs- Energy obtained from other organisms • Chemoheterotrophs - obtain energy by dissolving/absorbing organic material (Fungi, animals, most protists, & some plants) • Photoheterotrophs - meet some energy needs from photosynthesis, but must absorb organic compounds.(some marine & salt-loving prokaryotes)

11. Bacterial Respiration 3 major categories • Obligate aerobes. - Must have O2 in order to live • Obligate anaerobes - Must live in an O2 free environment • Facultative anaerobes - Can live with or without O2.

12. Bacterial Reproduction: • Bacteria reproduce through binary fission. • Can engage in primitive sexual reproduction called conjugation. • A bridge is formed between 2 bacteria • Plasmids are shared across bridge, thus exchanging genetic information. • In times of harsh conditions, some bacteria can form endospores, to encapsulate themselves in a dormant state, until conditions improve. sex pilus

13. Endospores • Thick protective coat, low level of water, and proteins to protect DNA from degradation.

14. Binary Fission

15. Motility • Some bacteria are motile - can move most commonly through use of a flagellum or many flagella http://faculty.ksu.edu.sa/shoeib/Flashes/Bacterial%20Motility.swf

16. Bacterial Behavior Taxis=movement towards or away from a stimulus Bacteria move toward nutrient-rich regions Aerobes move toward oxygen; anaerobes avoid it Photosynthetic types move toward light Magnetotactic bacteria swim downward Myobacteria show collective behavior Positive taxis is towards something Negative taxis is away from something 16

17. Eubacteria Ecology • Produce O2 • Fix Nitrogen (N2 NH3) • Decomposers

18. Eubacteria and Humans • Products: • Food: Yogurt, Cheese, etc. • Bioremediation: Oil spill clean up • Pesticides: Bacillus thuringiensis genes • Medicine: Insulin, growth factors, & antibodies http://www.ext.colostate.edu/pubs/insect/05556.html

19. Eubacteria and Humans

20. Archaea Evolutionary Relationships • Analysis of molecules found within the cells suggests that eukaryotes are more closely related to archaea than to bacteria. • Different from normal bacteria b/c of lack of peptidoglycan in their cell walls ?

21. Archaea Classification • Is confusing: • Archaea share traits with Bacteria • Cell type, shape, size, metabolism, reproduction • Archaea share traits with Eukaryotes • No Peptidoglycan in Cell Wall • Histones around DNA • Impervious to antibiotics • Introns present

22. Major Groups of Archaea • Three major groups of archaea are found in extreme habitats...extremophiles! • Methanogens are found in anaerobic environments, such as marshes and in the intestinal tracts of animals. They produce methane as a result of cellular respiration (can be found in animal guts, swamps, and hydrothermal vents) • Halophiles are found in environments with high salt concentration such as the great salt lake or soil with a high salt concentration. • Thermoacidophiles live in hot, acidic environments such as hot springs and hydrothermal vents.

23. Extreme Halophiles Live in highly saline environments (9%) Ex: Haobacterium

24. Extreme Thermophiles Live in extremely hot environments (85°C) Ex: Sulfolobus

25. Methanogens Commonly found in wet areas Converts CO2 to methane

26. Archaea Ecology Mutualism with Ruminant and Termites: Break down cellulose in animal gut

27. Archaea Ecology Lets not forget about cyanobacteria! ~3.5bya: Cyanobacteria start producing O2 (photosynthetic) Live in water Typically form colonies Can be considered phytoplankton Guess what this ends of being millions of years later…

28. Archaea and Humans Sewage Treatment Thermophillic Enzymes used in PCR http://www.ges-biosys.com/wwt/wwt_main.html