Entropy, potential energy and energy transduction

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Entropy, potential energy and energy transduction

Post by Hudson » Wed May 25, 2011 6:01 pm

Hello biologists!
I'm taking a college level intro to biochem course and i'm just getting starting. I have a study guide text book that I purchased, however, it only has practice questions and no answers are included!! I'm on the first chapter and I think i understand mostly everything so far, but I do have a question I'd like to ask to make sure I'm on the right track.

here is the question:

in terms of potential energy, energy transduction, and entropy, explain the following normal daily activities:eating, moving, excreting. Where do the sun and ATP fit into this scheme.

here is what I was thinking?

for eating - potential energy would be the action of opening your mouth, energy transduction would be closing your mouth/biting the food, and entropy would be the breakdown of food into smaller components? or are they thinking more on the lines of potential energy being he nutrients in the food, energy transduction is digestion/breaking down nutrients in body, and entropy would be what, excreting the food?

for moving, i was thinking potential energy would be raising your foot, energy transduction would be lowering your foot/stepping, and entropy would be moving forward?

for excreting i wasn't sure. maybe you could help me out with this one.

As for where does the sun or ATP fit into the scheme, i was thinking you could say the sun creates energy through photosynthesis, so it plays a part in the food we eat.

Anyway, let me know if you think im completely off track here or if i just need some guidance, or if my understanding is good.

Thanks! Ellie

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Post by mith » Thu May 26, 2011 10:46 pm

I think since it's a biochem course you should be discussion the relevant chemicals involved in the activities etc

e.g. excretion : Potential energy : ATP in the body is required to power the excretion machinery. A good example would be the nephrons and kidneys especially the osmolarity gradient created.

Transduction : discuss the actions of ATP on the sodium/potassium pumps (in creating the gradient described above)

Entropy - Discuss the starting materials (ATP and unfiltered blood) -> end materials
(ADP, filtered blood, urine)

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Re: Entropy, potential energy and energy transduction

Post by jonmoulton » Fri May 27, 2011 3:25 pm

"i was thinking you could say the sun creates energy through photosynthesis"

Be careful. Energy is neither created nor destroyed. Photosynthesis converts light energy to chemical energy, a transformation of energy not a creation of energy.

"entropy would be what, excreting the food"

Entropy is the degradation of high quality energy and pure chemicals to low quality energy and mixtures. The high quality chemical energy of carbohydrates and oxygen is converted to the low quality energy of carbon dioxide and water. Another way of saying that is the inputs (carbs and oxygen) become more stable outputs (CO2 and water). However, in respiration much of the energy difference is trapped to make less-stable biomolecules (NADH, ATP etc.) so the entropy increase is slower, awaiting use of the trapped biomolecular energy for maintaining membrane potentials, muscle motion, nerve activity etc.

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