Cells and Biochemistry

Photosynthesis is a really cool process that was first used by the cyanobacteria.  These bacteria made oxygen available in the earth's atmosphere millions of years ago and paved the way for the evolution of aerobic (oxygen-utilizing) organisms like us.  These early-photosynthetic organisms may have been engulfed by a non-photosynthetic single-celled organism to form the first plant-like eukaryotic organisms on the planet.  Plants are highly adapted organisms that use energy from the sun, carbon dioxide from the atmosphere, and water in a series of chemical reactions (utilizing enzymes and electron carriers) to generate sugars.  These sugars are their food source.  It also makes many of them very tasty to us and other organisms.  From the sugars they produce, they can make everything else (nucleic acids, amino acids and fatty acids) they need to survive, grow, and reproduce. For this reason plants are called autotrophs.   Auto means self and troph means nourishing.

Animals, on the other hand, have developed along a very different evolutionary line.  We move, hunt down our food, and ingest it to gain our source of many amino acids, sugars, and fatty acids.  We have an elaborate nervous systems to sense our environment and transmit this information to a central processing station, the brain, that enables us to react.  We have muscles to move and find food and we often need a lot of food to sustain our activity. We are very social and often engage in battles for the right to mate, be a part of the group, and/or eat.  I wonder if our behavior would change if we became photosynthetic and just hung around in the sun all day like a plant?  I surely hope that wouldn't mean our brains would become obsolete!  

Below are some questions to consider as you write your post:

If we were photosynthetic, could sugar alone sustain us?  Hint:  Can you survive on sugar alone now?

Would we still need to eat?  If so what and why?

How long would we need to stand out in the sun to make enough sugar to provide for our energy needs?

How could our epidermis which is made of dead skin cells packed with a protein called keratin be changed back into living cells to sustain the process of photosynthesis?  If not could the underlying living-skin cells be changed into photosynthetic cells?

How would carbon dioxide be provided?  For us, carbon dioxide is a waste product of cellular respiration that we expel through the lungs.

****Remember to focus your post on only one of the topics presented under the assignment details!****

I just realized that the incredible hulk is green.  Maybe his color comes from photosynthesis! If photosynthesis could give me his strength, I might consider being turned green.  On the flip side, I hate insects and they might like to munch on me a bit too much if my skin becomes as tasty and nutrient-filled as the tissue of some plants!  Nevermind, I'll keep my "omnivorous habits" and forgo the heat and the bugs!