Bio notes 9 - Zhaonan Liu Lecture 9 Cell Evolution 9/12/07...

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Zhaonan Liu 9/12/07 Lecture 9 Cell Evolution Prokaryotic Diversity and Numbers • Numbers: – Estimated 1030 prokaryotes on Earth – As many as 1014 microbial cells associated with an adult human body! Three orders of magnitude more than the number of people who ever lived (100,000,000,000)! – Our microbes extend our metabolic capabilities and aid in the development of our immune system – Most microbes are benign, or even useful, but we know the most about those that cause us harm (pathogens - disease causing) Prokaryotes are metabolically versatile… – Aerobic and anaerobic growth – Responsible for carbon cycling (fix CO2, decompose) – Generate components of our atmosphere O2, ozone – Use light to fix carbon (CO2), fix N2, derive energy from mineral transformations, biogeochemical cycling – Breakdown complex organics - bioremediation (using organisms to breakdown or clean-up pollution)! – Some have the capacity to live in environments where we could not survive: “extremophiles” Prokaryotes: Limited Morphological Diversity • Common shapes: cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped) • Other shapes: squares, stars, filaments Molecular Phylogenetic Analyses • Selection acts on variation in populations. This variety of traits is a result of variation in gene
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This note was uploaded on 02/23/2008 for the course BIO G 101 taught by Professor Gilbert,c. during the Fall '07 term at Cornell University (Engineering School).

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Bio notes 9 - Zhaonan Liu Lecture 9 Cell Evolution 9/12/07...

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