BCOR 12 1st Edition Lecture 10 Outline of Last Lecture I Protocells and Life Form Abilities II Geological Record of Earth s History III Some Key Event s in Life s History IV Photosynthesis the Oxygen Revolution V Endosymbiont Theory Outline of Current Lecture I Biodiversity II Prokaryote Abilities III Prokaryote Reproduction IV Common Characteristics of Prokaryotes V Factors that cause high genetic variability in prokaryotes Current Lecture Biodiversity the variety of living organisms in the biosphere includes all ecosystems or in a particular habitat or ecosystem o Biodiversity can be analyzed in a small sense habitat or in a large sense biosphere Prokaryotes were the first living organisms on Earth and have gone through about 4 billion years of evolution o They are the most abundant type of organism on the planet Prokaryote Abilities Amazingly efficient Reproduce at rapid rates a whole new generation can be developed in 20 minutes Archaeabactera extremophiles o Live in a variety of environments that are considered inhabitable o Ex Areas of very high pH or very low pH extreme high and low temperatures etc Bacteria true bacteria what we re more familiar with Prokaryotes have the unique ability to withstand a broad range of habitats o Ex The human gut the tundra the deep sea vents etc Prokaryote Reproduction Prokaryotes have a huge genetic diversity BUT they produce by means on binary fission These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Binary fission a method of asexual reproduction by division in half o Genome has to be fully replicated before prokaryotes can split Asexual reproduction reproduction without gametes meiosis or mitosis involved Bacterial chromosomes circular chromosomes o Most bacteria only have one chromosome Bacteria grow at an exponential rate Major evolutionary forces that can increase the fitness of bacterial individuals in a stressful environment would be mutation and natural selection o Mutation causes an advantage of one bacteria and natural selection selects for that mutation so it gradually becomes a large part of the gene pool Mutations are rarely passed on in multicellular organisms Common Characteristics of Prokaryotes All bacteria are unicellular Bacteria often live in colonies They come in three shapes o Spherical o Rod shaped o Spiral Fimibrae a short hair like appendage that helps a prokaryote adhere to a substrate or another cell Bacterial capsule a sticky layer that surrounds the cell wall of some prokaryotes It provides o Protection o Adhering to cell surface Plasmid an independently replicating DNA molecule and carries only a few genes that are usually not essential to the bacteria s survival but are helpful o Plasmids are used a lot in laboratories for transferring genes between organisms ALL BACTERIA HAVE A CELL WALL Genetic recombination when we get a new combination of alleles Remember mutations are a source of new genetic material Bacteria undergo genetic recombination in absence of sexual reproduction through the use of horizontal gene transfer the transfer of genes between living organisms of the same generation A mutation does not involve combination of genes Factors that cause High Genetic Variation in Bacteria I II III Rapid Reproduction Mutation Genetic recombination via horizontal gene transfer a Transformation the taking up of foreign DNA by a bacteria b Transduction involves a virus transferring DNA from one bacteria to another c Conjugation direct contact between bacteria is made and genes can be transferred Not all bacteria can do all the forms of genetic recombination o Transformation and conjugation have special genes that allow them to do the actions Bacteria are characterized by their nutritional modes and metabolic adaptations that have evolved in prokaryotes Nutrition modes o Autotrophs obtain necessary energy to fuel the work of the cell from light photo or chemicals when light is not available chemo ONLY prokaryotes can be chemoautotrophs Their energy sources are inorganic compounds o Heterotrophs require at least one organic nutrient ex Glucose to make another compound proteins lipids etc Photoheterotrophs are unique to prokaryotes Chemoheterotrophs are like humans where they eat to fuel themselves