Photosynthesis and Chloroplasts
You will read that only plants, algae, and some bacteria are photosynthetic. There is an exception to this, however. One species of sea slug has found a way to steal chloroplasts, store them in glands lining its digestive tract, and live on the sugar that is produced (Milius, 2010). The sea slug has even commandeered the genes to help repair these chloroplasts to keep them working for 9 months—longer than the algae would (Fang, 2015)!
What if animals and humans could be engineered to have chloroplasts and could then use photosynthesis?
Focus your discussion on 1 of the following topics:
• Describe at least 2 benefits and 2 drawbacks there might be for animal cells (including humans) to make their own food through photosynthesis.
• Explain which cells, tissues, or organs should be modified to lead to successful photosynthesis in animals or humans. Discuss how these compare to a plant’s leaves.
• Describe the process of photosynthesis to explain at least 1 requirement for photosynthesis that would need to be considered for chloroplasts to function in an animal or a human.
Sample Solution
Green skin is common in science fiction, from little green men to Hera Syndulla from “Star Wars Rebels” to Gamora from “Guardians of the Galaxy.” But what if green skin were not just for fictional aliens? If humans had green skin, for instance, what if it granted us the ability to perform photosynthesis which plants use to live off of sunlight? Even if our skin was riddled with working chloroplasts, they would only manufacture a fraction of the nutrients we need to survive. Animals need a lot of energy, and moving at all doesn’t really jive well with photosynthesis. Assuming the photosynthetic humans possessed chloroplasts, they might need porous skin to let in carbon dioxide, but such pores might let other things leak in or out – for instance, moisture – in ways that might prove detrimental to the human body.
