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1. ASWBAT describe the theory of Endosymbiosis.
2. ASWBAT identify 3 pieces of evidence that support the theory of Endosymbiosis
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On a scale of 1 – 3 how well you can do on this objective now.
1 – Not at all
Highlight your choice.
2 – I know it a little bit 3 – I know it very well)
Objective. 1
Objective. 2
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On a scale of 1 – 3 how well do you know the vocabulary words below.
( 1 – Not at all 2 – I know it a little bit 3 – I know it very well)
Chloroplast
Mitochondria
Symbiosis
Prefix “Endo”
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Do your best to answer the following questions.
1. What is symbiosis?
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2.
Is bacteria DNA circular or linear?
Answer:

Symbiosis
When two organisms live together and one or both benefit from it, we call it symbiosis.
For example, we have a symbiosis with e-coli bacteria. They live in our intestines and help us to digest protein and we in turn give food to the bacteria when we eat. Both humans and bacteria benefit from the relationship.
Examples of Symbiotic Relationships
1. What is symbiosis?
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2. Give an example of a symbiotic relationship.
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Prefix: “Endo”
The prefix “Endo” means inside of.
1. What does the prefix “Endo” mean?
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Theory of Endosymbiosis
Cells that contain a nucleus and membrane covered organelles are called Eukaryotes. Two of these organelles that are very important are called mitochondria and chloroplasts.
Mitochondria create energy from sugar and oxygen for almost all eukaryotic cells. We call this energy ATP. Chloroplasts use sunlight energy to create sugar. One very interesting thing about these two organelles is that are very similar to prokaryotes (bacteria).
Because they are so similar, scientists theorize that they must have began as independent living prokaryotes that where ingested by a eukaryote. When the prokaryotes that evolved into mitochondria where ingested by the cell they helped the eukaryote by producing energy for it. When the prokaryotes that evolved into chloroplasts where ingested by the cell it created sugar for the cell. In both cases the eukaryote was better off and the prokaryotes have lived inside of eukaryotes ever since. So scientists believe that both mitochondria and chloroplast evolved from a symbiotic relationship with prokaryotes.
Because the prokaryotes were inside of the eukaryotes, the theory is called Endosymbiosis.

Theory of Endosymbiosis – Chloroplast and mitochondria were once prokaryotes and now they live inside of eukaryotes.
Every theory needs to be supported by evidence. There are several pieces of evidence to support the theory. Here are four of the most obvious ones.
Evidence for the Theory of Endosymbiosis
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Mitochondria and Chloroplast have their own DNA
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The DNA is circular.
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Mitochondria and Chloroplast both reproduce by themselves without help from the nucleus.
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Mitochondria and Chloroplast have their own ribosomes that are like the ones that bacteria have.
1. Name 3 pieces of evidence that support the theory of endosymbiosis.
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Early Eukaryote
Modern Eukaryote
Quiz
1. What is the theory of endosymbiosis?
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2. What are three pieces of evidence that support the theory of endosymbiosis?
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3. After looking at the evidence, do you think that the theory is true? Why or why not? (No right or wrong answer)
Answer: