Biology Exam Prep: Evolution, Cell Division, and Life Classification

Vocabulary flashcards created from lecture notes covering evolutionary timelines, mass extinctions, cell division phases, evolutionary mechanisms, speciation, classification, viruses, and prions.

Miller-Urey Experiment (1953)

A 1953 experiment that simulated Earth's early anoxic atmosphere using water vapor, ammonia, methane, and hydrogen gas, producing complex organic molecules including amino acids, carbohydrates, lipids, and nitrogenous bases via electric sparks.

The Oxygen Revolution

The process where photosynthetic cyanobacteria released oxygen as a byproduct, which initially reacted with dissolved ocean iron to form banded iron formations before saturating water and gasing out into the atmosphere.

Endosymbiotic Theory

The theory stating that mitochondria and chloroplasts evolved from free-living prokaryotic cells that were engulfed by and began living inside early eukaryotic cells.

Law of Superposition

A principle for reading rock layers stating that oldest rocks and fossils are found at the bottom layers, while the newest rocks and fossils are at the top.

Late Ordovician Mass Extinction

A mass extinction event (443–445 MYA) that wiped out ~85% of species due to rapid cooling and glaciation.

Late Devonian Mass Extinction

A mass extinction event (360–375 MYA) that eliminated ~75% of species, driven by oceanic deoxygenation.

Permian–Triassic Mass Extinction

Also known as 'The Great Dying' at 252 MYA; the worst extinction in Earth's history, wiping out 96% of marine species and 70% of land species due to massive Siberian Traps volcanism.

Triassic–Jurassic Mass Extinction

A mass extinction event (201 MYA) driven by Pangaea breakup volcanism that killed 80% of species, clearing ecological niches for dinosaurs to dominate.

Cretaceous–Paleogene Mass Extinction

A mass extinction event (66 MYA) that killed 76% of species, famously wiping out non-avian dinosaurs due to the Chicxulub asteroid impact and volcanic stress.

Interphase

The cell cycle phase where the cell grows and DNA is replicated, consisting of the G1, S, and G2 phases.

Prophase

The mitotic phase where sister chromatids condense, the mitotic spindle forms, and the nuclear envelope breaks down.

Metaphase

The mitotic phase where chromosomes are most condensed and line up at the metaphase plate in the center of the cell, with spindle fibers attached to the kinetochore on the centromere.

Anaphase

The mitotic phase where sister chromatids are pulled apart by spindle fibers toward opposite poles of the cell.

Telophase

The mitotic phase where new nuclear membranes form around each set of separated chromosomes and chromosomes uncoil.

Cleavage Furrow

The mechanism of cytokinesis in animal cells where a contractile ring of microfilaments pinches the cell membrane in half.

Cell Plate Formation

The mechanism of cytokinesis in plant cells where vesicles containing cell wall material collect in the middle and fuse to build a brand new cell wall.

Mitosis

Cell division that produces 2 identical diploid (2n) somatic cells for growth and repair.

Meiosis

Cell division that produces 4 genetically diverse haploid (1n) gametes (sperm and eggs) through two rounds of division and crossing over.

Mutation

The alteration of DNA base-pair sequences, which serves as the ultimate source of all genetic variation.

Genetic Drift

Random change in allele frequencies due to chance events, which is stronger in small populations and includes the Founder Effect and Population Bottlenecks.

Migration (Gene Flow)

The movement of alleles into or out of a population.

Natural Selection

Differential reproductive success of individuals with heritable traits best suited to their environment.

Allopatric Speciation

Speciation that occurs when a geographic barrier physically separates a population, which can lead to adaptive radiation.

Sympatric Speciation

Speciation that occurs without geographic isolation, often through sudden chromosomal changes like polyploidy.

Linnaean Classification

A system developed by Carolus Linnaeus using a two-part scientific name consisting of the Genus and species.

Viruses

Infectious agents consisting of a DNA or RNA genome enclosed in a capsid protein coat, which are difficult to treat medically due to quick mutations and few unique targets.

Prions

Infectious agents composed entirely of abnormal proteins with no nucleic acid (DNA/RNA) that cause neurodegenerative brain diseases like mad cow disease, scrapie in sheep, and kuru by forcing normal proteins to misfold.