_07 Microbial Evolution and Sytematics.pptx - Microbial Evolution and Systematics • Microorganisms are the oldest life forms on Earth – Earth is

_07 Microbial Evolution and Sytematics.pptx - Microbial...

This preview shows page 1 - 12 out of 34 pages.

Microorganisms are the oldest life forms on Earth Earth is approx. 4.6 billion years old Prokaryotic organisms evident fossilized in rocks as old as 3.5 billion years old Microbial Evolution and Systematics
Image of page 1

Subscribe to view the full document.

Coccoid fossil (SEM) Filamentous fossil (thin section TEM) Prokaryotic Fossils
Image of page 2
Stromatolites Layers of prokaryotic cells fossilized in sedimentary rock
Image of page 3

Subscribe to view the full document.

Surface temperature > 100 o C Atmosphere rich in – H 2 O – CH 4 – CO 2 – N 2 – NH 3 Other substances – H 2 S FeS HCN No O 2 ! Early Earth
Image of page 4
Miller-Urey Experiment Demonstrated that organic molecules could form spontaneously from simple atmospheric gasses in primordial atmosphere Origins of Life on Earth
Image of page 5

Subscribe to view the full document.

FeS-rich minerals (Montmorillonite clays) could catalyze the synthesis of macromolecules Lipids can spontaneously form bilayer vesicles (coacervates) Ribonucleotides form RNA molecules RNA is encapsulated in lipid vesicles Cellular Evolution
Image of page 6
Evidence suggests that RNA was the first self-replicating molecule Earliest “cells” were probably RNA molecules encapsulated in lipid vesicles RNA-directed protein synthesis came later DNA as more stable “genome” evolved even later RNA World
Image of page 7

Subscribe to view the full document.

Iron/sulfur reduction used to drive ATP synthesis in primordial cells Elemental oxygen did not appear until evolution of photosynthetic cyanobacteria Energy Metabolism in Anoxic Earth
Image of page 8
Image of page 9

Subscribe to view the full document.

Bacteria, Archaea and eukaryotes evolved from a common proto-cellular ancestor Lynn Margulies postulated the endosymbiont theory to explain origin of cellular organelles Suggested that mitochondria and chloroplasts have bacterial origins Cellular Evolution
Image of page 10
The RNA polymerases of organelles resemble
Image of page 11

Subscribe to view the full document.

Image of page 12
  • Spring '14
  • LawrenceR.Aaronson

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes