LO6 Flashcards
Recognize important events in the History of Life on Earth •Draw and be able to explain the key features of the tree of life, including the evolutionary relationships with the common ancestor of all living organisms, major split between the two prokaryote domains, and the origin of eukaryotes. •Recognize the extensive uncertainty at the base of the tree, as horizontal gene transfer makes it more a network than a dichotomous tree.
What are Prokaryotes?
Prokaryotes were Earth’s sole inhabitants for more than 1.5 billion years.
What caused Photosynthesis and the Oxygen Revolution and what impact did it have?
Most atmospheric oxygen (O2) is of biological origin.
The O2 revolution marks a change in Earth’s atmosphere, due to photosynthezing prokaryotes (not plants!)
What is the endosymbiont theory?
proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells as prey or internal parasite.
What was the Cambrian explosion?
A ‘Sudden’ appearance of fossils resembling modern animal phyla in the Cambrian period: 535 to 525 mya. The major transition from water to land.
What was the colonization of land?
Fungi, plants, and animals began to colonize land about 500 mya.
Plants and fungi likely colonized land together using mutually beneficial associations (mycorrhizae).
What impact did the five mass extinction events have?
In each of the five mass extinction events, 50% or more of marine species became extinct.
What was the Permian extinction?
96% of marine animals went extinct
Start of Mesozoic, ‘Age of Dinosaurs’
What was the KT extinction?
End of Mesozoic
‘Age of Dinosaurs’
Start of Cenozoic
‘Age of mammals’
What are the three main groups within the tree of life?
The three groups include Bacteria, Archaea, and eukarya
Also, note that Archae and Eukarya are more closely related to one another.
Which domain of life are plants and animals?
Eukarya
What are the four clades of eukaryotic life?
Excavata
SAR clade
Archaeplastida
Unikonta
What are the three major groups of multi-cellular organisms?
Fungi
Animals
Plants
What is horizontal gene transfer?
the movement of genes from one genome to another.
What is vertical gene transfer?
Movement of genes from parent to offspring.
Why is horizontal gene transfer important?
Horizontal gene transfer has played a key role in the evolution of both prokaryotes and eukaryotes.
