mcdb20lec11su09

mcdb20lec11su09 - Lecture 11. Evolution and Diversity Among...

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Lecture 11. Evolution and Diversity Among the Microbes -Bacteria -Archaea -Protists -Viruses and beyond Learning Objectives ! Know there are microbes in all three domains ! Know that bacteria may be the most diverse of all organisms ! Know how bacteria impact their environment ! Know that bacteria can be helpful or harmful Learning Objectives ! Know that archaea exploit some of the most extreme habitats ! Know that protists are (mostly) single- celled eukaryotes ! Know that viruses are at the border between living and non-living ! Know that new non-cellular infectious agents are still being discovered Microbes are the simplest, but most successful organisms on earth. What is a MICROBE? Micro = small Cannot see with naked eye Human eyes can only resolve ~ 170 ! m INVISIBLE WORLD until THE MICROSCOPE Robert Hooke’s microscope ca. 1665 Modern microscopes ca. 2000
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Atomic Force Microscope ca. 2000 Different concept Uses force to “trace” structures on a smooth surface Atomic-level resolution Nanoscope. developed at UCSB E. coli cell circular plasmid DNA Microbes Are Genetically Diverse ! >500,000 kinds ! Millions more expected to be distinguished! ! a drop of water contains as many microbes as there are people in a medium-sized city. Microbes Can Live Almost Anywhere and Eat Almost Anything Microbes are related by size only, not by evolution.
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Most, not all, Bacteria are small and only visible with microscopes What are bacteria? ! Bacteria are efficient single-celled organisms that lack nuclei and the intracellular organelles, such as mitochondria, that are found in eukaryotic cells. Bacterial cells: single compartment Cell membrane Surrounds cell Regulates internal & external environment Cytosol Interior fluid compartment single circular chromosome Most bacteria have one of two distinct types of cell wall Bacteria Chemistry of their cell walls The number and placement of flagella Metabolic reactions Their ability to form spores DNA sequences 25 • Identified by – Simple shapes Bacteria Carry Genetic Information in Two Structures 1) A circular DNA molecule called the chromosome (1 or more) 2) Circular DNA molecules called plasmids carry genees for specialized traits metabolic plasmids resistance plasmids virulence plasmids 27 ! Genetic information is efficiently organized ! virtually all the DNA codes for proteins. ! genes are organized in groups with related functions that are transcribed together into mRNAs coding for several proteins
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Bacterial growth and reproduction is fast and efficient. the “Numbers Game” ! Bacterial cells undergo binary fission, and a single cell can grow into a colony of cells. 31
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This note was uploaded on 09/14/2009 for the course MCDB 20 taught by Professor Cooper during the Summer '08 term at UCSB.

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mcdb20lec11su09 - Lecture 11. Evolution and Diversity Among...

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