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Bacteria and Archaea Prokaryotic organisms Premedical - Biology.

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Presentation on theme: "Bacteria and Archaea Prokaryotic organisms Premedical - Biology."— Presentation transcript:

1 Bacteria and Archaea Prokaryotic organisms Premedical - Biology

2 They are (almost) everyvwhere! Their history starts 3,5 billions years ago Dominate the biosphere Inhabit the human mouth or skin, digestive system – 500 – 1,000 species Only minority ot them cause disease in humans or any other organism

3 They are able to adapt in structure and function, in nutrition and metabolism Reproduction, mutation and genetic recombinatoin promote genetic diversity

4 Bacterial structure

5 Prokaryotes unicellular groups of two or more cells, true colonies sphere (cocci) rods (bacilli), helices (spirilla, spirochetes) 0.5-5μm (10-100μm for eukaryotic cells) Staphylococcus aureus

6 Cell walls protection (hypotonic enviroment) would die in hypertonic medium (heavily salted meat) different from plant, fungi, protists cell walls peptidoglycan (polymers of sugar cross-linked by short peptides that vary from species to species) Tool in microbial taxonomy is Gram stain – separate into two groups based on differencies in cell walls Gram positive – large amount of peptidoglycan Gram negative – less peptidoglycan, outer membrane of lipopolysaccharides (LPS), carbohydrates bonded to lipids, Lipoteichoic acids (LTA)

7 Gram positive and Gram negative

8 Patogenity Gram negative are more threatening LPS of negative are often toxic Outer membrane is protect against hosts and antibiotics Antibiotics, like penicillins, inhibit synthesis of cross- links in peptidoglykan and prevent the formation Capsule - adherention to substrate, protection, gelatinous glue the cells to colonies Pili, pilus - adherention, to mucous membrane, conjugation – DNA transfer some product antibiotics

9 Pathogenic prokaryotes Cause about one half of all human diseases Some pathogen are opportunistic – normal residents of a host, but can cause illness, when the host‘s defences are weakened. Pathogen caused illnesses by producing Exotoxins: proteins secreted by prokaryotes, (botulism, cholera) Endotoxins – components of the outer membranes of certain Gram-negative bacteria (Salmonella)

10 Movement directional movement – 100 times their body length per second Flagelar action - most common mechanism, scattered over the entire cell surface or at one or both ends of the cell The flagella of prokaryotes and eukaryotes differ in function and structure

11 motility of spirochetes – two or several helical filaments under the outer sheath of the cell taxis movement – toward or away from stimulus chemotaxis phototaxis

12 Genomic organization Not true nuclei enclosed by membranes Not compartmentalization by internal membrane systems DNA is concentrated in nucleoid region – prokaryotic chromosome – one double stranded molecule in the form of ring essential functions programmed by chromosome small rings of DNA – plasmids – resistance to antibiotics, metabolism of unusual nutrients Replicate independently of the main chromosome


14 Division binary fission – „division in half“ generation time is measured in minutes or hours bacterial chromosome is attached to the plasma membrane

15 Grow of populations temperature, pH, salt concentrations, nutrient sources More multiplication of cells than to the enlargement of individual cells Generation time in the range of 1 to 3 hours, number of cells doubling with each generation During lag phase, bakteria adapt themselves to growth conditions Exponential phase is a period characterized by cell doubling During stationary phase, a result of nutrient depletion and accumulation of toxic products At death phase, bacteria run out of nutrients and die

16 Endospores -The ability of some prokaryotes to withstand hard conditions - The cell replicates chromosome, the copy became surrounded by a durable wall, outer cell disintegrates, endospore contained survives all sorts of trauma: lack of water, nutrients, extreme heat or cold, almost poisons Clostridium tetani Bacillus cereus, Bacillus subtilis. (1, 4) central endospore; 2, 3, 5) terminal endospore; (6) lateral endospore

17 Sporulation

18 Grow of populations prokaryotes lack sexual cycle, important source of genetic variation Three mechanisms of genetic recombination Transformation – genes are taken up from surrounding environment Conjugation – genes are transferred directly from one to another Transduction – genes are transferred between prokarytoes by viruses

19 Bacterial transformation naked DNA passess into recipient cells, Griffith (1928) 1. experiment Avery, McLeod, McCarthy (1944) – the same effect with isolated DNA finally homologous recombination: the exchange of homologous parts


21 Transduction Bacteriophages transmit spontaneously bacterial genes Special – restrictions mistakes within cutting out of bacteriophage from bact. genome General – into small parts of phages particles is packed bacterial DNA instead of phages one

22 Bacterial conjugation Donor’s plasmid F + passes into acceptor’s cell F -, Conjugation by cytoplasmatic conjugative bridge there is the exchange of homologous parts

23 How an organism obtain two resources for synthesizing organic compounds: energy and a source of carbon

24 plants algae Certain prokaryotes Marine and halophilic prok. Fungi, animals, most protist,

25 Photoautotrophs use light-energy to drive synthesis of organic compounds from carbon dioxide; internal membranes with light-harvesting pigment systems; Chemoautotrophs need only CO 2 as a carbon source, obtain energy by oxidizing inorganic substances: hydrogen sulfide (H 2 S), ammonia (NH 3 ), ferrous ions (Fe 2+ ) Photoheterotrophs use light-energy to generate ATP, but must obtain carbon in organic form; Chemoheterotrophs must consume organic molecules for both energy and carbon

26 Metabolic diversity is greater among prokaryotes than all eukaryotes combined. Able to use various organic and inorganic molecules from the atmosphere (CO 2, N 2 ) Primary metabolism: anaerobic, heterotrophic than autotrophic Anaerobic bacteria - some disappeared, inhabition anaerobic environments, symbiosis, parasitism Metabolism

27 Symbiosis „living together“- ecological relationships between organissm of different species that are in direct contact; symbionts – if one is much larger than the other, the larger is termed host Mutualism - both symbionts benefit Commensalism - one symbionts receive benefits while neither harming nor helping the other in any significant way Parasitism – one symbiont, called a parasite, benefits at the expense of the host; patogene Many prokaryotes are symbiotic

28 Metabolic relantioship to oxygen Obligate aerobs – cellular respiration Facultative anaerobs – if it is present, use it. They use fermentation in an anaerobic enviroment Obligate anaerobs are poisoned by oxygen, use fermentation or extract energy by anaerobic respiration – inorganic molecules accept electrons

29 Autotrophic Bacteria organism that makes organic compounds from inorganic sources synthesize organic compounds from carbon dioxide and other inorganic elements (CO 2, H 2 S) or molecules using either light energy or chemical energy. green sulphur bacteria, purple sul-phur bacteria and the purple norisulphur bacteria,

30 Heterotrophic Bacteria the majority are chemoheterotrophs organism that cannot make organic compounds from inorganic sources. They depend on small or large molecules which they have to absorb. There are three types of heterotrophic bacteria : saprophytic or saprobic, parasitic and symbiotic. Pseudomonas, Staphylococus, Escherichia coli

31 Prokaryotes, Archae and Eubacteria Common ancestor 3,5 bilion years ago

32 – Two branches of prokaryotic evolution were identified by comparing ribosomal (16S-rRNA) RNA and completely sequences genomes of several extant species. – Archaea inhabit extreme inviroments, hot springs and salt ponds – Archea have at least as much in common with eukaryotes as they do with bacteria; have many unique traits. Archae

33 Phylogeny of prokaryotes domain Archea Methanogens – unique form of energy metablism, H 2 is used to reduce CO 2 to methane CH 4. Oxygen is a poison. Live in swamps and marshes and other species inhabit the gut of animals. Extreme halophiles – live in saline places as the Great Salt Lake and the Dead sea Extreme thermophiles – thrive in hot enviroments, temperatures are of 60°C to 80°C, thermal springs

34 domain Bacteria – five groups of Bacteria (based mainly on comparision of sequences in ribosomal RNA 1. Proteobacteria purple bacteria – photoautotrophs, photoheterotrophs with bacteriochlorophylls, obligate anaerobes chemoautotrophic proteobacteria – free-living and symbiotic species, nitrogen fixation chemoheterotrophic proteobacteria – enteric bacteria, facultative anaerobes (Salmonella, E. coli)

35 2. Gram-positive bacteria Some are gram-negative, some are photosynthetic, most are chemoheterotrophs (Clostridium, Bacillus) Mycoplasmas – the smallest of known cells, μm, only bacteria that lack cell walls Actinomyces Soil bacteria resemble fungi, commercial sources of antibiotics

36 3. Cyanobacteria Photoautrophs with plant-like photosynthesis, fresh water, marine species, symbionts, single-cell from, colonies and truly multicellular organisms 4. Spirochetes Helical chemoheterotrophs, some are very long (up to 0.25mm), internal flagelar-like filments providing corkscrew- like movement, Treponema pallidum, Borrelia Burgdorferi

37 5. Chlamydias Obligate intracellular parasites of animals, obtain ATP from the host cell, gram-negative, Chlamydia trachomatis cause blindness and sexually transmitted disease

38 Research and technology Simple model systems Escherichia coli – the prokaryotic „ white rat“ Soil bacteria called pseudomonas decompose pesticides, petroleum componeds and other. The food industry uses bacteria to convert milk to yogurt and various kind of cheese. Gram stain of yogurt, 1000x with Lactobacillus acidiphilus

39 Borrelia burgdorferi – Lyme disease Treponema pallidum - syphilis Neisseria gonorrhoeae - gonorrhoea Neisseria meningitis – cerebro-spinal meningitis Salmonella typhi – typhus Bordetella pertusis – whooping cough Staphylococcus aureus – skin suppuration Staphylococcus pneumonie – pneumonia Streptococcus pyogenes – angina, sore throat Streptococcus pneumonie – pneumonia Most widely known pathogenic bacteria:

40 Clostridium tetani - tetanus Clostridium botulinum- botulism Bacillus anthracis - anthrax Mycoplasma pneumonie – pneumonia Shigella dysenterie- red pestilence, dysentery Vibrio cholerae – cholera Mycobacterium leprae - leprosy Mycobacterium tuberculosis - tuberkulosis Corynebacterium diphterie - diphtheria Haemophilus influenzae – inflammation of airways Rickettsia prowazeki - spotted fever Pasteurella (Versinia) pestis – plague Francisella tularensis - tularemia

41 Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson, Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings Publishing Company, 1996 –2010.

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