Endosymbiotic Theory Summary

Endosymbiotic Theory Overview

• Definition: The Endosymbiotic Theory explains how eukaryotic cells evolved from prokaryotic cells through a process of engulfment and symbiosis.

Key Concepts

• Prokaryotes: Simple cells that existed about 2 billion years ago.

• Endocytosis/Engulfment: Larger prokaryotic cells engulf smaller bacteria instead of digesting them.

• Symbiotic Relationship: Mutual benefit; smaller bacteria provide energy, while the larger cell offers protection.

Evolution of Organelles

• Oxygen-using Bacteria: Evolved into mitochondria, crucial for energy production in eukaryotes.

• Photosynthetic Bacteria: Evolved into chloroplasts, enabling photosynthesis in plant cells.

Evidence Supporting the Theory

• Mitochondria and chloroplasts have their own DNA, separate from the cell's nucleus.

• They possess a double membrane, similar to bacteria.

• They can reproduce independently within eukaryotic cells.

Modern Implications

• Animal cells contain only mitochondria.

• Plant cells contain both mitochondria and chloroplasts, reflecting their mixed energy-producing functions.