BGM1004/L18 Origin of Eukaryotes Flashcards
How early is there evidence for prokaryotic life?
3.75 BYA
When is the earliest evidence for eukaryotes?
1.6 BYA
How old is the red algal Bangiomorpha fossil?
1.3 billion years old
How do eukaryotes compare to bacteria evolutionarily?
Eukaryotes much younger than bacteria
What does the Hominid group consist of?
All modern and extinct Great Apes
What is morphology useful for?
Constructing evolutionary relationships for animals (not bacteria)
How is an evolutionary tree made from molecules? (4)
Alignment of genes or protein sequence
Measure similarity
Convert similarity using mathematical model
Draw a tree
Give an example of a complex chronometer.
SSU rRNA
What is SSU rRNA called in bacteria?
16S SSU rRNA
What is SSU rRNA called in eukaryotes?
18S SSU rRNA
What was the first universal domains tree of life based on?
SSU rRNA sequences
Why are genes rarely replaced by lateral gene transfer?
Negative selection against replacement of genes is very strong
Which two domains are separate groups sharing a common prokaryotic ancestor?
Archaea and Eukarya
What is a LECA?
Last Eukaryotic Common Ancestor
What is an ancestral character state?
Features present in cells such as genes or membranes
Present or absent
What outgroup can be used for mammals?
Reptiles
What outgroup can be used for the tree of all cellular life?
Cannot be determined
How can the outgroup problem for all cellular life be overcome?
Using ancient gene duplications that occured in LUCA of life
What are elongation factors?
GTPases that drive translation forward and improve its accuracy
What do EF-Tu and EF-G in bacteria correspond to in eukaryotes?
EF-1 and EF-2 (respectively)
What are paralogues?
Duplicated genes across different species
Where are Crenarchaeota (Eocytes) traditionally isolated from?
Extreme environments
How can a new tree be constructed where eukaryotes originate from within archaea?
Adding new Archaea SSU rRNA sequences
What is the difference in the 2 domains/eocyte tree?
Basal split is between Bacteria and Archaea group, fitting fossil record
Why is it said that eukaryotes are much more complex than prokaryotes?
Many proteins underpinning their complexity claimed to be unique to eukaryotes
What are Asgard Archaea said to be most closely related to?
Eukarya
How were Asgard Archaea identified?
Metagenomics