Endosymbiotic theory

Okay kiddo, do you know what cells are? They are tiny building blocks that make up all living things. Now, let me tell you about something called endosymbiotic theory.

A long time ago, before humans and even before dinosaurs, there were tiny cells that were all alone. Then, some cells started living together and formed bigger cells. This is called symbiosis.

One day, some big cells ate smaller cells but instead of digesting them, they kept them inside. These smaller cells became part of the bigger cells and started helping them. This is called endosymbiosis.

Over time, these smaller cells evolved and became important organelles (parts) of the bigger cells. One organelle that developed this way is called mitochondria. Mitochondria are very important because they give cells energy to grow and live.

Another organelle that developed this way is called chloroplasts. Chloroplasts help plants make food by using sunlight. This is called photosynthesis.

The endosymbiotic theory explains how these important organelles became a basic part of cells. It was a process that took a long, long time and it all started with tiny cells living together. Cool, huh?