Ch. 25: The History of Life on Earth and Its Evolution

Macroevolution

Evolutionary changes above the species level.

Fossil Record

Evidence of macroevolution over large time scales.

Abiotic Synthesis

Formation of organic molecules without biological influence.

Macromolecules

Large molecules formed from smaller organic compounds.

Protocells

Droplets with membranes maintaining distinct internal chemistry.

Self-replicating Molecules

Molecules capable of duplicating themselves independently.

Early Earth Conditions

High water vapor, volcanic gases, low oxygen atmosphere.

Earth's Formation

Earth formed approximately 4.6 billion years ago.

Volcanic Eruptions

Released compounds like nitrogen and carbon dioxide.

Oparin and Haldane

Scientists proposing early Earth organic compound synthesis theory.

Haldane's Hypothesis

Early atmosphere was a reducing environment.

Miller-Urey Experiment

Demonstrated abiotic synthesis of organic molecules.

Reducing Conditions

Conditions near volcanoes may have formed organic compounds.

Deep-Sea Hydrothermal Vents

Hot water and minerals create organic compounds.

Murchison Meteorite

Contains amino acids and other organic molecules.

Abiotic RNA Synthesis

All four RNA monomers can form spontaneously.

Protocells

Fluid-filled vesicles with membrane-like structures.

Montmorillonite

Mineral clay that enhances vesicle formation.

Vesicle Properties

Exhibit growth, reproduction, and metabolism.

Self-Replicating RNA

First genetic material likely was RNA, not DNA.

Ribozymes

RNA molecules that catalyze biochemical reactions.

Natural Selection in RNA

Faster replicating RNA shapes dominate.

DNA Assembly Template

RNA could template DNA nucleotide assembly.

Fossil Record

Documents history of life through sedimentary layers.

Sedimentary Rock

Most fossils are found in these rock types.

Mineralized Fossils

Form when minerals replace organic matter.

Trace Fossils

Preserve evidence of organism activities.

Amber Fossils

Organisms preserved in tree resin.

Frozen Fossils

Rarely preserve larger organisms in ice.

Fossil Bias

Favors long-lived, abundant, hard-bodied species.

Relative Dating

Infers sequence of fossil formation.

Radiometric Dating

Determines fossil age using radioactive isotopes.

Carbon-14 Dating

Estimates age based on carbon isotope ratios.

Isotope Decay

Parent isotopes decay to daughter isotopes.

Geologic Record

Divides Earth's history into four eons.

Tetrapods

Group of animals with four limbs.

Synapsids

Tetrapods from which mammals evolved.

Therapsids

Synapsids with specialized teeth and large dentary bones.

Cynodonts

Early therapsids with complex teeth and jaw structure.

Mammalian Teeth

Specialized for function: incisors, canines, molars.

Geologic Time Scale

Relates major life events to Earth's history.

Stromatolites

Layered rocks formed by prokaryotic activity.

Oxygen Revolution

O2 accumulation transformed Earth's atmosphere.

Endosymbiosis

Eukaryotes originated from engulfed prokaryotes.

Serial Endosymbiosis

Mitochondria evolved before plastids.

Evidence for Endosymbiosis

Mitochondria share similarities with bacteria.

Multicellularity Origin

Eukaryotic cells led to multicellular life.

Ediacaran Biota

Oldest multicellular fossils from 600 million years ago.

Cambrian Explosion

Rapid appearance of animal phyla in fossils.