A2.1.9 Evidence for the evolution of the last universal common ancestor

What are hydrothermal vents?

Extraordinary environments where superheated water interacts with cold seawater, precipitating minerals like iron sulfides and silicates.

How old is the oldest known evidence of life?

Over 3.5 billion years.

What type of fossils provide clues about early life?

Fossils of microbial life, such as stromatolites.

Where is the Strelley Pool Formation located?

Western Australia.

What are stromatolites?

Layered rock structures created by mats of microorganisms, likely cyanobacteria.

How old are the stromatolites found in the Strelley Pool Formation?

Dating back 3.42 billion years.

What do the formation conditions of stromatolites suggest?

That microbial life had already diversified by that time.

Why are hydrothermal vents considered candidates for the origin of life?

They provide energy sources, catalytic surfaces, and compartmentalization for chemical reactions.

What chemicals are emitted by hydrothermal vents?

Hydrogen, methane, and other reduced chemicals.

What role do minerals like iron sulfides play in the origin of life?

They may have catalyzed the formation of organic molecules.

What is the significance of the porous structure of vent deposits?

It could have provided isolated microenvironments for chemical reactions.

What is the temperature range of alkaline hydrothermal vents?

60-90C

How many conserved protein families have been identified across bacteria and archaea?

355 protein families.

What does the conservation of ribosomes and DNA polymerases suggest?

That these features were present in LUCA and preserved through evolution.

Why are rRNA sequences useful in evolutionary studies?

They are among the most conserved genetic elements and can be used to reconstruct evolutionary relationships.

What do fossils provide in the study of early life?

Tangible evidence of ancient microorganisms.

What are the challenges in using fossils and genomic data to study the origin of life?

Fossil ambiguity and incomplete genomic data.

What is a common misconception about LUCA?

That LUCA was the first living cell, when in fact, LUCA is the last shared ancestor of all current life.

What broader implication does the existence of life in hydrothermal vents on Earth suggest?

That similar environments on other celestial bodies, like Europa or Enceladus, could harbor life.

How does the concept of LUCA challenge our understanding of "unity and diversity" in biology?

LUCA represents a shared ancestor, highlighting the interconnectedness of life despite its diversity.