Chapter 25 History of Life on Earth Flashcards
What are the 4 conditions of early Earth that made origin of life possible?
- Abiotic synthesis of small organic molecules
- Joining of these small molecules into macromolecules
- Packaging of molecules into protocells
- Origin of self-replicating molecules
How long ago did Earth form? What gases were potentially found there?
- formed 4.6 billion years ago
- nitrogen, nitrogen oxide, carbon dioxide, ammonia, methane, and hydrogen could have all been found
What is the abiotic synthesis of macromolecules?
When small organic molecules polymerize when concentrated on hot sand, clay, or rock
What are protocells?
Cells that may have formed from fluid filled vesicles with a membrane-like structure
- could have been vesicles containing RNA capable of replication
Why is it that RNA could have been the first genetic material?
B/c their molecules, ribozymes, have been found to catalyze many different reactions and can be replicated quicker/more stable
What kind of species do fossils favor?
those that have:
- existed for a long time
- were abundant and widespread
- has hard parts
Radiometric dating
Absolute age of fossils that’s determined by their measurement
Isotope
Has a known half-life which is the time required for half of the parent isotope to decay
What are tetrapods?
Mammals that belong to the group of animals
What is the geologic record?
A record divided into:
- Hadean
- Archaean
- Proterozoic
- Phanerozoic
What are the 3 eras of the Phanerozoic?
- Paleozoic
- Mesozoic
- Cenozoic
What are stromatolites?
Oldest known fossils formed by the accumulation of sedimentary layers on bacterial mats
- dates back 3.5 billion years ago
What is the oxygen revolution?
Oxygen accumulation and rusting of iron-riched terrestrial rocks that caused the extinction of many prokaryotic groups
- 2.7 to 2.3 BYA
What is the endosymbiont theory?
Proposed that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells
Endosymbiont
A cell that lives within a host cell
- cells ends up splitting in an animal or plant cell
What is serial enodymbiosis?
Supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
What is the cambrian explosion?
Refers to the sudden appearance of fossils resembling modern animal phyla in the cambrian period
- provides the first predator-prey interactions
What are some key evidence of supporting endosymbiotic theory?
- inner membrane are similar to plasma membranes of prokaryotes
- Division and dna structures are similar in some organelles and prokaryotes
- organelles transcribe and translates their own DNA
- Ribosomes are more similar to prokaryotic than eukaryotic ribosomes
What was the colonization process of earth?
- Plants and fungi likely colonized land together
- Tetrapods evolved from love-finned fishes
- Human lineage evolved from tetrapods
- We see the modern human arrive 195,000 years ago
What is the theory of plate tectonics?
Earth’s crust is composed of plates floating on Earth’s mantle
How does plate tectonics occur?
- Plates move slowly through continental drift
- Oceanic and continental plats collide, separate, and slide past each other which cause physical formations and earthquakes
What were the effects of Pangaea?
- deepening of ocean basins
- reduction in shallow water habitat
- colder and drier climate on land
Consequences of continental drift on organisms
- Causes a continent’s climate to change as it moves directions
- Separation of land masses can lead to allopatric speciation
What is mass extinction?
Result of disruptive global environmental changes that causes species to dramatically die off
How many mass extinctions has there been?
5 mass extinctions
Permian Extinction
Defines the boundary b/w Paleozoic and Mesozoic era where 96% of marine animal species went extinct
Cretaceous Extinction
Occurred 65.5 MYA. about 1/2 of all marine species, many terrestrial plants, and animals including dinosaurs went extinct
What are some consequences of mass extinctions?
- can alter ecological communities and niches
- can change the type of organisms found in ecological communities
Adaptive Radiation
Rapid evolution of diversly adapted species from a common ancestor
When does adaptive radiation occur?
- after mass extinction
- colonization of new regions
- evolution of novel characteristics
Homeotic Genes
Genes that determine basic features such as where the legs will develop
Paedomorphosis
Rate of reproductive development that accelerates compared to somatic development
Heterotrophy
Evolutionary changes in the rate of timing of developmental events
- has significant impact on body shape
Regional Adaptive Radiation
Can occur when organisms colonize new environments with little competition
How should evolutionary trends be looked at?
It should be analyzed in a broader context
