A2.1

Cells

Basic structural and functional units of life that arise only from preexisting cells.

Zygote

The fertilized egg from which all cells in the body can be traced back.

LUCA

Last Universal Common Ancestor, the origin of all cells.

Hadean Eon

The early period of Earth's history characterized by extreme conditions, including volcanic activity and high UV radiation.

Prebiotic Earth

The state of Earth before life, marked by conditions unsuitable for life.

Spontaneous Generation

The theory that living organisms can arise from nonliving material, which has been disproven.

Miller-Urey Experiment

A 1953 experiment that simulated early Earth conditions and demonstrated the formation of organic compounds.

Polymerization

The process of combining small molecules to form larger chain-like molecules called polymers, essential for life.

RNA

A polymer formed from nucleotide monomers, believed to have preceded DNA and capable of self-replication.

Abiogenesis

The process by which life arises naturally from non-living matter.

Pasteur's Experiment

An experiment that disproved spontaneous generation by showing that organisms only grew in broken flasks.

LUCA Evidence

All living cells contain DNA, indicating a common ancestral cell.

Chemoautotroph

An organism that derives energy from chemical reactions, likely characteristics of LUCA.

Eukaryotes

Organisms with complex cells that originated through infolding of plasma membranes and endosymbiosis.

Endosymbiosis

The process by which chloroplasts and mitochondria evolved from independent prokaryotes living within host cells.

Mitochondria

Organelles that produce energy for the cell and are thought to have evolved before chloroplasts.

Multicellularity

The condition of being composed of multiple cells, providing advantages such as longer life spans and increased complexity.