1. Describe what you see happening in this picture:
Warm-Up
Describe what you see happening in this picture:

2. Endosymbiosis
Unit 5

3. Unit 5
Endosymbiosis
Cells can eat other cells. This is called engulfing.
One day, one bacteria cell engulfed another bacteria cell.
But, it didn’t digest the bacterium because it could do photosynthesis.
Video

4. Unit 5
Endosymbiosis
Scientists think this is how the chloroplast was born.
The chloroplast is where photosynthesis occurs.
Therefore, the chloroplast was once a bacteria cell.

5. Sentence stem: If the chloroplast was bacteria it should have…
Unit 5
Turn and Talk
If the chloroplast is a bacteria, then what do you think we should see inside the chloroplast?
Hint: think about the characteristics of bacteria. What is the evidence that the chloroplast was once a bacteria cell.
Sentence stem: If the chloroplast was bacteria it should have…

6. Unit 5
Endosymbiosis
The cell that engulfed the chloroplast also engulfed a cell that could make lots of ATP. Scientists think this is how the mitochondria was born.
The mitochondria is where cellular respiration occurs.
This is the endosymbiotic theory, or the theory that the chloroplast and mitochondria came from living bacteria.

7. Unit 5 Endosymbiosis DNA ribosomes double membrane
What is the evidence of the endosymbiotic theory?
In both mitochondria and chloroplast we see:
DNA
ribosomes
double membrane

8. Activity
Endosymbiotic Theory CER

9. Explain what evidence supports the endosymbiotic theory.
Closure
Explain what evidence supports the endosymbiotic theory.
Sentence stem:
The three pieces of evidence that support the endosymbiotic theory are….