GEOL 102 Lecture Notes - Lecture 14: Lynn Margulis, Uraninite, Archean

26 views7 pages
31 Mar 2017
School
Department
Course
Geology 102 Lecture 14 Notes
Archean Eon
Archean Life
The first organisms would have been prokaryotes
Prokaryotes are organisms whose genetic material is not contained in a cell
nucleus
Prokaryotes are generally divided into two large groups
Archaea
Bacteria
Fossils of many prokaryotes are difficult to identify in the absence of genetic data
Broadly categorized by morphology, chemistry
Indirect Evidence of Life
Photosynthesis- 3.7 bya
Methane production- 3.5 bya
Stromatolites
While largely unicellular some prokaryotes can form into communal masses
called biofilms
Fossils of layered biofilms are called stromatolites
Oldest stromatolites have been found in Australia and are dated to 3.45 bya
Interpreted as cyanobacteria- blue- green algae
Very common fossils by the late Archean persist in modern ecosystems
Modern ones consist of photosynthetic organisms
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in
Possible that not all fossil examples were
Eukaryotes
Organisms with a cell nucleus containing their genetic material
Includes some unicellular organisms and all multicellular ones, including animals
plants fungi
Many also have organelles- specialized subunits of cells
Some seem to represent remnants of early symbiotic relationships
Lynn Margulis (1938-2011) American biologist
Endosymbiosis, 1960s
Mitochondria- originally proteobacteria
Chloroplasts- originally cyanobacteria
Earliest eukaryote fossils are from the Proterozoic Eon 2.1 bya
Multiple examples from roughly the same time most represent eukaryotic algae
Indirect Evidence of Eukaryotes
Organic steranes have been found in Archean rocks dated to 2.7 bya
The kind of steranes discovered are only produced by chemical reactions in
eukaryotic cells today
Oxygen in the Archean
Earth’s earliest atmosphere contained very little free oxygen
Atmospheric oxygen came from three sources
Weathering
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in

Document Summary

The first organisms would have been prokaryotes. Prokaryotes are organisms whose genetic material is not contained in a cell nucleus. Prokaryotes are generally divided into two large groups. Fossils of many prokaryotes are difficult to identify in the absence of genetic data. While largely unicellular some prokaryotes can form into communal masses called biofilms. Fossils of layered biofilms are called stromatolites. Oldest stromatolites have been found in australia and are dated to 3. 45 bya. Very common fossils by the late archean persist in modern ecosystems. Possible that not all fossil examples were. Organisms with a cell nucleus containing their genetic material. Includes some unicellular organisms and all multicellular ones, including animals plants fungi. Many also have organelles- specialized subunits of cells. Some seem to represent remnants of early symbiotic relationships. Earliest eukaryote fossils are from the proterozoic eon 2. 1 bya. Multiple examples from roughly the same time most represent eukaryotic algae.

Get access

Grade+20% OFF
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers