Chp 25 Origin and History of Life

Flashcards covering the key concepts of the origin and history of life, including evolution, hypotheses for life origin, and the fossil record.

What are the four overlapping stages of life origin?

1. Nucleotides and amino acids produced prior to cell existence; 2. Polymerization into larger molecules; 3. Polymers enclosed in membranes forming protocells; 4. Origin of self-replicating molecules.

How long ago did the first prokaryotic cells appear?

The first prokaryotic cells appeared approximately 3.5 to 4 billion years ago.

What is the deep-sea vent hypothesis?

It suggests that biologically-important molecules may have formed in the pH gradient between alkaline vent water and acidic ocean water.

What is a protocell?

A protocell is an aggregate of pre-biotically produced molecules that acquired a boundary, allowing it to maintain a distinct internal environment.

What are the four characteristics of a protocell?

1. Boundary separating external environment from internal contents; 2. Polymers inside contained information; 3. Polymers had enzymatic function; 4. Protobionts capable of self-replication.

Why is RNA considered important in early life?

RNA can store information, self-replicate, and has enzymatic functions.

What factors bias the fossil record?

1. Hard body parts are more likely to be preserved; 2. Larger organisms are more likely to be found; 3. Abundance and environmental context of organisms affect preservation.

What is radiometric dating?

A technique used to estimate the age of fossils by measuring the amount of a given isotope and its decay products.

What major environmental changes have affected living organisms?

Climate/temperature changes, atmospheric changes, landmass shifts, floods, glaciation, volcanic eruptions, and meteoric impacts.

What is the Cambrian explosion?

A significant period of rapid diversification of animal species that occurred around 541 million years ago.

What role do developmental genes play in evolution?

They compare the development of different organisms to understand ancestral relationships and mechanisms for evolutionary change.