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Chapter 25: The History of Life (Timeline (3,500 million years ago (Oldest…
Chapter 25: The History of Life
Timeline
4,600 million years ago
Farthest back date recorded
Archean Time Period
3,500 million years ago
Oldest fossils of prokaryotic cells form at this time
Earliest form of life develops (stromatolites)
Stromatolites and prokaryotes live in the Earth
Stromatolites
- layered rocks formed by prokaryotes binding thin films of sediment together
2.7 billion years ago
Oxygen starts to pollute air & water
Oxygen dissolved in water and elements in water such as iron
Iron precipitates into iron oxide, which accumulates into sediments, which turn into iron ore
Oxygen gets into water and is released in the atmosphere
Photosynthetic prokaryotes similar to cyanobacteria begin to form
2.5 billion years ago
Eukaryotic cells appear
Diverse algae and soft-bodied invertebrate animals begin to form
Neo-Proterozoic
- 1 billion to 541 million years ago
Edicaran
- 635 to 541 million years ago
1.8 billion years ago
Marking point for eukaryotic organisms
Plasma membrane for ER, nuclear envelope, vacuoles, and other things begin to infold
Endosymbiont theory forms mitochondria and chloroplasts
1.2 billion years ago
Multicellular organisms begin to pop up
Small red algae, for example, starts to form
535-525 million years ago
Cambrian Explosion
Chapter 26: Phylogeny and the Tree of Life
Classification
Binomial Nomenclature
Genus goes first and first letter is capitalized
Species comes next as 2nd part and is all lowercase
Every part of the name is italicized when mentioned in print
(i.e
Panthera pardus
)
Hierarchical Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Taxon
- taxonomic unit at any level of hierarchy classification (i.e
Panthera
is taxon for genus)
Phylogenetic Tree
Tree that classifies organisms based on DNA structure and considers homologies and analogies between organisms
Different branches all come from a common ancestor
Molecular & Morphological
Homologies
When organisms share a common ancestor based on their similar structures and genetic material
Analogies
When organisms look similar due to convergent evolution instead of sharing a common ancestor
Convergent Evolution
- when two organisms evolve similar even though they don't share a common ancestor
Usually due to organisms being in similar environments, thus causing to evolve similar