W17 L2 - From Molecules to Macroevolution

Flashcards about the origin of life and evolution, covering topics from molecule formation to mass extinctions.

What are prezygotic and postzygotic barriers related to?

They are barriers that stop two species from hybridizing.

What is the focus of macroevolution?

The beginning of life on Earth and the evolution of complex functions.

When did the Earth form?

Around 4.6 billion years ago.

What was the atmosphere like on early Earth?

Water vapor and chemicals like nitrogen, methane, and ammonia but almost no oxygen.

What does 'abiotically' mean in the context of the origin of life?

That organic molecules formed without the presence of life or enzymes.

What is abiogenesis?

The origin of life from inanimate organic and inorganic molecules.

What did the Miller-Urey experiment demonstrate?

That abiotic systems can synthesize organic molecules in conditions simulating early Earth.

What did the analysis of the Murchison meteorite reveal?

It contained 90 different amino acids, suggesting they could have been delivered to Earth by meteorites.

What are ribozymes?

RNAs that can have enzymatic functions.

What is the RNA world hypothesis?

The hypothesis that life started with RNA instead of DNA.

How can RNA polymers form without enzymes?

By shaking nucleotides together on a clay surface.

What are protocells?

Precursors of cellular life, consisting of RNA inside a lipid membrane.

How did protocells likely form?

Fatty acids binding together in water to form lipid bilayers.

What role did natural selection play in protocell evolution?

Mutations that made protocells more stable and reproductive led to their proliferation.

What are stromatolites?

Rocks formed by layers of bacteria, representing some of the oldest known fossils.

What caused the oxygen revolution?

Cyanobacteria producing oxygen through photosynthesis.

What is the endosymbiosis theory?

The theory that mitochondria and chloroplasts were once bacteria engulfed by larger cells.

How did multicellular eukaryotes evolve from unicellular eukaryotes?

Through the fusion of membranes between cells, leading to more compacted organisms.

What is convergent evolution?

Independent evolution of similar structures, exemplified by the squid eye and the human eye.

When did animals appear?

Around 500 million years ago during the Cambrian explosion.

What characterizes mass extinctions?

A high rate of species extinction, killing at least 50% or more of all species.

What caused the Permian mass extinction?

Likely volcanic activity increasing CO2 levels and causing global warming.

What caused the KT mass extinction?

An asteroid impact that led to the extinction of dinosaurs.

What is causing the current potential mass extinction?

Human activity leading to increased extinction rates.

What is adaptive radiation?

Rapid evolution of species sharing a common ancestor, often following a mass extinction.

what are prezygotic barriers

Factors preventing mating or fertilization between species, such as temporal, behavioral, or mechanical isolation.

what are postzygotic barriers

Factors that occur after fertilization, preventing the successful development or reproduction of hybrid offspring, such as hybrid inviability or hybrid sterility.