BIOL 112 1nd Edition Lecture 16 Outline of Last Lecture I Hox genes II Earth is approximately 4 6 billion years old Outline of Current Lecture III Life accurate replication and metabolism IV Lipid membranes V What did LUCA look like VI Evidence of first prokaryote VII Bacterial cell organization VIII Cell wall protection but not permeable IX Gram ve bacteria gram ve bacteria gram stains cell wall Current Lecture Life accurate replication and metabolism Lipid membranes o Lipids have a tendency to form vesicles in aqueous solutions o Lipid vesicle selective barriers concentrates compounds inside increase probability of interaction provided a controlled environment o Clay from volcanic acts as a catalyst for RNA uptake into lipid vesicle Fig 25 3 o RNA probably the first genetic material because of intrinsic properties Can self assemble Can fold into 3D structures that can self cleave o Later smitten to DNA because DNA is more stable Proto cell prokaryote What did LUCA look like o Had characteristics common to bacteria and archaea o Bacteria and archaea DNA genome Nonnuclear envelope Electron transport ATP or ATP analogs Proteins Same genetic code Both present in LUCA 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 o Bacteria and archaea differ rDNA gene sequences Cell wall composition Evidence of first prokaryote o Fossil evidence prokaryote stromalites Stromalites fossilized prokaryotes Date to 3 5 billion years ago o Early prokaryote cyanobacteria Produce O2 to increase atmospheric O2 Increase O2 rust formation in rocks Date to 2 75 billion years ago Bacterial cell organization o 1 5 u diameter c f eukaryotic cell 10 100 u diameter o Common shapes Cocci sphere Baccili ros Spiral helical o Cell wall surrounds plasma membrane Cell wall protection but not permeable o Molecules can be transported across it in order of cell via diffusion or facilitated or via membrane proteins o Hypertonic solution cause bacteria to lose fluid and shrink death o Hypotonic solution are used as preservatives high sugar or high salt Gram ve bacteria gram ve bacteria gram stains cell wall o Gram ve bacteria don t stain because of extra membrane that impedes stain access to cell wall
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