Discussion Board – Endosymbiosis

A. Watch the following videos and study the materials

• Endosymbiotic theory (by Amoeba sisters, 5;30 min) (Links to an external site.)
• Endosymbiosis theory (by Bozeman Science, 7 min) (Links to an external site.)
• Endosymbiosis (2 min) (Links to an external site.)
• Evidence for endosymbiosis (Links to an external site.)
• Evidence that an endosymbiosis-like process is working today (Links to an external site.)

B. Post a paragraph discussing ONE of the following questions (5 pts):

1. Do you think endosymbiosis useful for living organisms? Why?
2. Do you think similar events that led to the endosymbiosis are happening to today? What are they?
3. What data support endosymbiosis theory? Do you think they are reasonable arguments? explain.

C. Then, read your class-mates posts and reply to at least two of your classmates. Your comments should be meaningful (not simply “Yeah, me too” or “I agree”). (2.5 pts for each full meaningful response). Make sure you include following in your reply:

• start by greeting the class-mate by name
• contribute to one or two of his/her discussion point with your view
• Pose any related questions you might have
• your name

D. Answer any questions you might get from class-mates

reply 1:

3. The data that supports the endosymbiosis theory is actually quite interesting. In eukaryotic cells the mitochondria and chloroplast have something very different about them when compared to other organelles. Both mitochondria and chloroplasts contain some of their own DNA which supports the theory of endosymbiosis. These organelles containing their own DNA supports the idea that at one point they were separate organisms and later became part of eukaryotic cells as we know them today,

reply 2:

3. Mitochondria seem like they used to be bacteria. That is the supporting idea to the endosymbiosis theory. The mitochondria have similar DNA to bacteria, mitochondria has its own cell membrane like bacteria does, and bacteria and mitochondria reproduce the same way. I think the arguments that support the theory are reasonable and make a lot of sense. Mitochondria basically acts the same way as bacteria in ways that other organelles do not. The most important supporting argument is about how the mitochondria has similar DNA to bacteria. The DNA is also passed down from the parent cell to the offspring which further supports that its possible and likely that mitochondria was its own organism at one point. I also found it interesting that, according to the theory, the mitochondria went from being its own organism to becoming reliant on the host cell and the host cell being reliant on the mitochondria. Now it is all one organism rather than two different ones living together. It is interesting to think about how overtime things fuse from two separate things into one.