Ch. 4 Evolutionary Origin of Cells and Their General Features

Anoxic

Refers to an environment or condition that lacks oxygen.

Protobionts

Simple, prebiotic structures that are considered to be precursors to living cells.

Liposomes

Small, spherical vesicles made of lipid bilayers similar to the membranes of cells.

Prokaryote

A single-celled organism that lacks a nucleus and membrane-bound organelles.

Eukaryote

An organism whose cells have a defined nucleus and membrane-bound organelles.

Cytosol

The gel-like substance that fills the interior of the cell, excluding the organelles.

Nucleus

The membrane-bound organelle in eukaryotic cells that contains the cell's genetic material (DNA).

Endomembrane System

A network of membranes within a eukaryotic cell involved in the synthesis, modification, and transport of proteins and lipids.

Semiautonomous Organelles

Organelles that have their own DNA and can reproduce independently but rely on the cell for some functions.

Endosymbiosis

The theory that suggests mitochondria and chloroplasts originated from free-living prokaryotes that were engulfed by a host cell.