BGM1004/L18 Origin of Eukaryotes

Question 1

How early is there evidence for prokaryotic life?

Answer 1

3.75 BYA

Question 2

When is the earliest evidence for eukaryotes?

Answer 2

1.6 BYA

Question 3

How old is the red algal Bangiomorpha fossil?

Answer 3

1.3 billion years old

Question 4

How do eukaryotes compare to bacteria evolutionarily?

Answer 4

Eukaryotes much younger than bacteria

Question 5

What does the Hominid group consist of?

Answer 5

All modern and extinct Great Apes

Question 6

What is morphology useful for?

Answer 6

Constructing evolutionary relationships for animals (not bacteria)

Question 7

How is an evolutionary tree made from molecules? (4)

Answer 7

Alignment of genes or protein sequence
Measure similarity
Convert similarity using mathematical model
Draw a tree

Question 8

Give an example of a complex chronometer.

Answer 8

SSU rRNA

Question 9

What is SSU rRNA called in bacteria?

Answer 9

16S SSU rRNA

Question 10

What is SSU rRNA called in eukaryotes?

Answer 10

18S SSU rRNA

Question 11

What was the first universal domains tree of life based on?

Answer 11

SSU rRNA sequences

Question 12

Why are genes rarely replaced by lateral gene transfer?

Answer 12

Negative selection against replacement of genes is very strong

Question 13

Which two domains are separate groups sharing a common prokaryotic ancestor?

Answer 13

Archaea and Eukarya

Question 14

What is a LECA?

Answer 14

Last Eukaryotic Common Ancestor

Question 15

What is an ancestral character state?

Answer 15

Features present in cells such as genes or membranes
Present or absent

Question 16

What outgroup can be used for mammals?

Answer 16

Reptiles

Question 17

What outgroup can be used for the tree of all cellular life?

Answer 17

Cannot be determined

Question 18

How can the outgroup problem for all cellular life be overcome?

Answer 18

Using ancient gene duplications that occured in LUCA of life

Question 19

What are elongation factors?

Answer 19

GTPases that drive translation forward and improve its accuracy

Question 20

What do EF-Tu and EF-G in bacteria correspond to in eukaryotes?

Answer 20

EF-1 and EF-2 (respectively)

Question 21

What are paralogues?

Answer 21

Duplicated genes across different species

Question 22

Where are Crenarchaeota (Eocytes) traditionally isolated from?

Answer 22

Extreme environments

Question 23

How can a new tree be constructed where eukaryotes originate from within archaea?

Answer 23

Adding new Archaea SSU rRNA sequences

Question 24

What is the difference in the 2 domains/eocyte tree?

Answer 24

Basal split is between Bacteria and Archaea group, fitting fossil record

Question 25

Why is it said that eukaryotes are much more complex than prokaryotes?

Answer 25

Many proteins underpinning their complexity claimed to be unique to eukaryotes

Question 26

What are Asgard Archaea said to be most closely related to?

Answer 26

Eukarya

Question 27

How were Asgard Archaea identified?

Answer 27

Metagenomics