Early Life and the Diversification of Prokaryotes

These flashcards cover key concepts from the lecture on early life and the diversification of prokaryotes, focusing on their characteristics, origin, and genetic diversity.

What defines prokaryotes?

Prokaryotes are informal terms for single-celled organisms in the Domains Bacteria and Archaea.

What are the steps by which simple cells may have originated from nonliving materials?

1. Abiotic synthesis of small organic molecules 2. Joining of small molecules into macromolecules 3. Packaging of molecules into protocells 4. Origin of self-replicating molecules.

What structural feature differentiates Gram-positive bacteria from Gram-negative bacteria?

Gram-positive bacteria have a simple wall with a thick layer of peptidoglycan, while Gram-negative bacteria have a more complex wall with a thin layer of peptidoglycan and an outer lipopolysaccharide layer.

What are the main nutritional categories of prokaryotes?

Prokaryotes can be categorized as autotrophs, heterotrophs, phototrophs, and chemotrophs.

How do prokaryotes increase genetic diversity?

Prokaryotes increase genetic diversity through transformation, transduction, and conjugation.

What is the role of ribozymes in early life?

Ribozymes are RNA molecules that can catalyze reactions and may have played a role in early protocells' self-replication.

What are the characteristics of early Earth's atmosphere that allowed for the abiotic synthesis of organic compounds?

Early Earth's atmosphere had little oxygen and contained water vapor, along with chemical compounds from volcanic eruptions like nitrogen, ammonia, methane, and hydrogen.

What is a protocell?

A protocell is an abiotic precursor of a living cell, typically with a membrane-like structure that maintains a unique internal chemistry.

What are the major prokaryotic phylogenetic groups?

Major prokaryotic phylogenetic groups include Bacteria and Archaea.

What evidence suggests life originated on Earth about 3.8 billion years ago?

The first chemical signatures of life date back to 3.8 billion years ago, and the earliest fossil evidence of organisms dates back to 3.5 billion years ago.