Prokaryotes PDF

Prokaryotes I- Diversity of Prokaryotes  Taxonomy of living organisms This timeline shows how the shape of the tree of life has changed over the centuries. Even today, the taxonomy of living organisms is continually being reevaluated and refined with advan...

Prokaryotes I- Diversity of Prokaryotes  Taxonomy of living organisms This timeline shows how the shape of the tree of life has changed over the centuries. Even today, the taxonomy of living organisms is continually being reevaluated and refined with advances in technology  Prokaryote classification and diversity Before: - Kingdom Monera (contains organisms of Bacteria and Archea) - Kingdom Protista - Kingdom Fungi - Kingdom Plantae - Kingdom Animalia (There is no such thing as domain here) After: - Domain Bacteria - Domain Archea - Domain Eukarya which contains: -------- Kingdom Protista -------- Kingdom Fungi -------- Kingdom…  UPDATE: So here's what people thought happened: /archea /prokaryotes-bacteria /-protists ancestor--fungi \-plants \animals SECOND UPDATE: ancestor-bacteria \nonbacteria-archea \eukaryotes-protists \something-plants \something-fungi \animals  The Prokaryotes Bacteria and Archea: - What are prokaryotes? - A type of organism lacking a membrane-enclosed nucleus and membrane-enclosed organelles.  Bacteria& Archae There are almost everywhere !!! They are the most numerous organisms that can be found in all habitats  Prokaryotes Appear approximately 3.5 BYA Were the earliest living organisms Have specialized into all habitats Have all types of metabolism – Origin of aerobic and other types of respiration – Origin of several types of photosynthesis  Prokaryotes Very few cause diseases As fixers and decomposers they are essential in geo-chemical cycles Many form symbiotic relationships with other prokaryotes and eukaryotes Mitochondria and chloroplasts may be descended from symbiotic bacteria  Prokaryotes The two prokaryote domains, Bacteria and Archaea, split from each other early in the evolution of life. Bacteria are very diverse, ranging from disease- causing pathogens to beneficial photosynthesizers and symbionts. Archaea are also diverse, but none are pathogenic and many live in extreme environments. A DNA sequencing approach called metagenomics lets scientists identify new species of bacteria and archaea, including ones that can't be cultured.  Prokaryotes as compared to eukaryotes Typically smaller in size Lack membrane bound organelles Most have cell walls – but different chemical composition Have simpler genomes  Morphological Diversity of Prokaryotes Cells have a diversity of shapes the most common being – spheres (cocci) – rods (bacilli) – helices (spirilla and spirochetes). Prokaryotes are generally single-celled – some aggregate into two-celled to several celled groups – Some have specialized functions, heterocysts in Anabaena.  Morphological Diversity of Prokaryotes Cells have a diversity of shapes the most common being – spheres (cocci) – rods (bacilli) – helices (spirilla and spirochetes). Prokaryotes are generally single-celled – some aggregate into two-celled to several celled groups – Some have specialized functions, heterocysts in Anabaena.  Shapes of bacteria Bacteria  Classification of Prokaryotes What features separate the Bacteria from the Archaea? Characteristic Bacteria Arachaea Peptidoglycan yes no Reponse to growth growth antibiotics inhibited not inhibited Growth above no some species 100ºC  All prokaryotes were classified into a single domain (the largest taxonomic grouping). Carl Woese in the 1970s showed that prokaryotes are divided into two distinct lineages, or lines of descent: Archaea and Bacteria. The third domain (Eukarya) includes all eukaryotes, such as plants, animals, and fungi.  Woese make his break through discovery by studying ribosomal RNA sequences from many different organisms. Ribosomal RNA (rRNA) genes are often used to build evolutionary trees, or phylogenies, that show relationships among species. rRNA genes are good for determining evolutionary relationships among species (how related one species is to another) because they have the same function across organisms and evolve slowly over time. This phylogeny (evolutionary tree) depicts the evolutionary relationships between the three domains of life: Eukarya, Archaea, and Bacteria Classification of Prokaryotes Alpha Gram positive Beta Gram negative Gamma Proteo- bacteria Delta Epsilon Chlamydias Spirochaetes Cyanobacteria Gram positive bacteria Archaea  Classification of Prokaryotes Alpha Proteobacteria -e.g. Rhizobium - nitrogen fixing in plant roots Beta Proteobacteria -several soil bacteria Gamma Proteobacteria -some pathogens - Salmonella (food poisoning) Legionella (Legionnaire’s disease) Vibrio cholerae (Cholera) Delta Proteobacteria -several soil bacteria Epsilon Proteobacteria -gastrointestinal infections  Classification of Prokaryotes Chlamydias -venereal disease Spirochaetes -disease organisms Treponema pallidum - syphillus Borrelia burgdorferi - Lyme disease Classification of Prokaryotes Gram positive Bacteria -very diverse group Some familiar ones: Streptomyces - antibiotic production Classification of Prokaryotes Gram positive Bacteria -very diverse group Some familiar ones: Streptomyces - antibiotic production Bacillus anthrax - anthrax Classification of Prokaryotes Cyanobacteria - only prokaryotes with plant-like photosynthesis  Classification of Prokaryotes Archaea - differ from bacteria in several ways but have no peptidoglycan Common in extreme conditions 1. Thermophiles - live at extreme temperatures (>100ºC) Pyrolobus -in deep sea vents Classification of Prokaryotes Archaea - differ from bacteria in several ways but have no peptidoglycan Common in extreme conditions 2. Halophiles - live at extreme salinities Classification of Prokaryotes Archaea - differ from bacteria in several ways but have no peptidoglycan Common in extreme conditions 3. Methanogens - use CO2 to oxidize H2 - release CH3 - “swamp gas”