THE HISTORY OF LIFE ON EARTH

Flashcards covering key vocabulary and concepts from the lecture 'The History of Life on Earth', including origins of life, geological evidence, eukaryotic evolution, and macroevolutionary changes.

Scientific Evidence (Origins of Life)

Three sources of evidence for the origins of life: Chemical, Geological, and Molecular.

Miller-Urey Experiment

An experiment that simulated early Earth conditions to demonstrate the abiotic synthesis of small organic molecules.

Earth's Early Atmosphere

Composed of water vapor and chemicals from volcanic eruptions (Nitrogen, Nitrogen Oxides, CO2, Methane, Ammonia, Hydrogen, Hydrogen Sulfide) with almost no oxygen.

Cyanobacteria

Among the first types of life on Earth, they introduced oxygen into the atmosphere through photosynthesis.

Reducing Atmosphere

A condition on early Earth characterized by an absence of O2 and a high amount of H, requiring little energy to form carbon-rich molecules.

Abiotic Synthesis

The first stage in the origin of very simple cells, involving the formation of small organic molecules from non-living matter.

Protocells

Primitive cells characterized by a surrounding membrane or membrane-like structure, capable of packaging molecules.

First Genetic Material

Probably RNA, which could also act as a catalyst (ribozyme) and provide a template for DNA formation.

Fossil Record

Geological evidence that reveals changes in the history of life on Earth, documenting both extinct and extant species.

Stromatolites

The oldest known fossils, consisting of rocks formed by the accumulation of sedimentary layers on bacterial mats.

Endosymbiosis

The process by which eukaryotic cells originated, when a prokaryotic cell engulfed a smaller cell that would evolve into an organelle like a mitochondrion or chloroplast.

Endosymbiotic Theory

Hypothesizes that mitochondria and chloroplasts originated from prokaryotic cells living inside larger host cells in a mutually beneficial relationship.

Cellular Specialization

A process where cells become specialized to perform certain functions, a hallmark of multicellular organisms.

Three Domains of Life

The major molecular and genetic separations of life on Earth: Bacteria, Archaea, and Eukarya.

Multicellularity

The state of being composed of multiple cells, which evolved and gave rise to algae, plants, fungi, and animals.

Cambrian Explosion

A sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535-525 million years ago).

Colonization of Land

The process by which fungi, plants, and animals began to inhabit terrestrial environments around 500 million years ago.

Plate Tectonics

The theory that Earth's crust is composed of plates floating on the Earth's mantle.

Continental Drift

The process where movements in the Earth's mantle cause the tectonic plates to move over time.

Pangaea

A supercontinent that formed about 250 million years ago, leading to significant environmental and biological changes.

Allopatric Speciation

A process where a population becomes separated by a geographic barrier, leading to reproductive isolation and the development of two separate species.

Mass Extinction Events

Periods in Earth's history where 50% or more of marine (and often terrestrial) species became extinct.

Permian Extinction

The largest mass extinction event, occurring 252 million years ago, leading to the extinction of about 96% of marine animal species.

Cretaceous Mass Extinction

Occurring 66 million years ago, it led to the extinction of over 50% of marine species, many families of terrestrial plants and animals, and all non-avian dinosaurs.

Adaptive Radiation

The rapid evolution of diversely adapted species from a common ancestor, often following mass extinctions, the evolution of novel characteristics, or the colonization of new regions.

Evo-Devo

The merging of evolutionary and developmental biology, studying how changes in developmental genes can lead to major changes in body form.

Heterochrony

An evolutionary change in the rate or timing of developmental events, leading to altered morphology.

Homeotic Genes

Genes that determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged.

Hox Genes

A class of homeotic genes that provide positional information during animal embryonic development, controlling the body plan along the anterior-posterior (head-tail) axis.

Gene Duplication

A molecular mechanism where new morphological forms likely come from gene duplication events that produce new developmental genes.