Question: "Phytoplankton, Chemosynthesis, and Mitochondria"

For your primary post, please respond to one of the following three topics with a post of at least 125 words that addresses each point given in the instructions. Also, please reply to at least one fellow student on any topic.

Topic 1 [video]: The phytoplankton that brought Earth to life. Review the video (1)* about the "phytoplankton that brought Earth to life" from the link given below. In this clip, which is under 5 minutes in length, Penny Chisholm discusses a tiny phytoplankton called Prochlorococcus. Based on that video, please address the following:

• (a) What is the importance of Prochlorococcus for life on the planet Earth, both historically and in the present day?

• (b) In the video, Dr. Chisholm tells us that Prochlorococcus samples from different environments are genetically different. What does this tell us about the relationships between organisms and their environments?

• (c) Explain how this relates to this week's lessons.

Topic 2 [article]: Snails that don't eat. A recent article by JoAnna Klein (2)* describes a partnership between the snail Gigantopelta chessoia and a chemosynthetic bacterium. The bacterium is called an "endosymbiont" because it lives inside the snail.

• (a) Describe the partnership between Gigantopelta chessoia and its endosymbiont.

• (b) What is most surprising to you about this situation?

• (c) Explain how this relates to this week's lessons.

Topic 3 [article]: Exercise and mitochondria. Exercise is generally known to have many beneficial effects on our bodies at several different levels. Some studies have examined the effects of exercise at the level of muscle cells. Read the press release by Cell Press (3)*.

• (a) What specifically did these researchers measure in their volunteers?

• (b) What were their findings?

• (c) Explain how this relates to this week's lessons.