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Diversity of Life and Prokaryotes

4 Pages

Biology (Sci)
Course Code
BIOL 111
Irene Gregory- Eaves

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08/09/12 Diversity of life and Prokaryotes Diversity of life: - Biodiversity: Degrees of difference in: 1) Genetic variation (gene level) 2) Species compostion (species diversity) 3) Interactions with ecosystem (abiotic/biotic, across and within) - More diverse environments are healthier (eg. purify water, detox) Species diversity: number of species in a habitat as well as their relative abundance Edwin (1983) tree fogging: Chose a tree in the amazon, covered it and killed everything in symbiosis with it, finding: - 160 beetle species unique to that particular type of tree - 50000 tree species - 2/5 insects are beetles - insects ½ all species Number of species on earth is unknown, - 1.5 million species named - 13000 new species named each year - 3000 synonyms (duplicates) - 3 to 100 million eukaryotic species living today - bacteria and archaea numbers are unknown (~10 000 bacteria identified, but could be millions to 100 millions) - 99% species are extinct Factors controlling diversity: Area: In general, doubling sample area increases number of species by 10-25% (more area = more species) Climate: warm, wet areas have more species for reasons unknown (eg. Tropics are more diverse  near equator: warmer, wetter support diversity) Human have a bias towards the study of plants and vertebrates, though these are not the most diverse, genetically, functionally nor by species: - Arthropods are most diverse eukaryotic phylum (62% of all eukaryotes) - Beetles most diverse of them (35% of arthropods) nd - Plants 2 , followed by mollusks, vertebrates and fungi - Fish most diverse vertebrates (49% of all vertebrates) Genetic diversity: measure of genetic distance (=evolutionary separation) Functional diversity: differences in shapes, size, where animals live - Prokaryotes show greatest genetic and functional diversity Prokaryotes: oldest organisms 08/09/12 pro – before karyon – kernel 1. Barcteria (eg. Cyanobacteria) 2. Archea (closely related to eukarya than to bacteria) Characteristics: - No nucleus: - Nucleoid region - concentrated area where genetic material is found - chromosome not super coiled, in a ring - plasmids: extra-chromosomal DNA; arranged in small rings = easily exchanged during sex - No membrane bound organelles  cell membrane become folded for respiration/photosynthesis = ATP synthesis without organelles - 70s ribosomes (smaller than 80s of eukaryotes)  lack of nucleus allows for simultaneous transcription and translation of entire genome = fast growth/reproduction (eg. E. coli reproducted every 20 minutes) - No cytoskeleton - Cell wall, made of peptidoglycan in bacteria - Photosynthesis in some (ie. cyanobacteria) Archea: - No peptidoglycan in cell wall - Distinctive lipids that eukaryote and bacteria don’t have - Many have lipid monolayer: phospholipids with two heads and connecting tails Bacterial diversity: bacteria have a variety morphologies - unicellular, colonial 1. spheres = cocci 2. rod = bacilli 3. helical = spirili - gram positive = blue/purple when stained - thick cell wall + plasma membrane - gram negatice = red
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