# The second law of thermodynamics and the cell (3 questions)? [closed]

1. How is that the cell maintains internal order, yet it discharges heat (disorder) to the surrounding?
2. If the cell is supplied with materials for metabolism and growth by the surroundings (disorderly environment), then how does that disorder generate order inside the cell?
3. When we zoom out from a single cell to a multi-cellular organism, will the net value of internal order of cells decrease disorder which would contradict the 2nd law of thermodynamics?
Note:I would appreciate serious informative answers. The questions are important for me no matter how silly they may look like for you.

## closed as off-topic by David, Charles, Bryan Krause♦, kmm, WYSIWYGNov 1 '17 at 10:47

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• I think you're neglecting an important point: the 2nd law applies to closed systems, and the cell (or multi-cellular bodies) is not a closed system. It takes energy from outside to maintain its organization. Place it in a closed box, and it will die when it has used up its internal reserves. – jamesqf Oct 20 '17 at 17:32
• @jamesqf Alas, Schrödinger's cat was doomed from the beginning. – Bryan Krause Oct 20 '17 at 22:23
• What research have you done yourself to answer this old chestnut? I entered "life and the second law of thermodynamics" in my web browser and got a page full of links on this topic, including one that Google had highlighted. – David Oct 21 '17 at 0:26

First question: the answer is actually contained within the question. The cell maintains order precisely by discharging heat. The second law of thermodynamics states that the tendency of a closed system is to proceed from ordered to disordered. Since thermal energy is (to our knowledge) the most disorderly form of energy that exists, in any given system where energy is involved, some energy will always be lost to heat.

For instance, if your cell performs the break down of ATP to drive some chemical need of the cell, some of the energy released in the breaking of the bonds in the ATP to form ADP will be lost as heat. This means that the cell's heat is going up on average, and it must export heat to the environment. If the heat was held inside the cell, the cell would rapidly become extremely disordered as proteins de-natured, non-enzymatic reactions sped up, and the cell basically self-destructed.

Second question: I think you've slightly missed something. Autotrophs (producer cells, such as plants) are the cells to actually "create order" in the biosystem. They do this by capturing Carbon dioxide and water from the environment, and using light energy from the sun to bond them together and form complex biomolecules - usually carbohydrates.

These carbohydrates are then sent into the rest of the biosystem, where heterotrophs (consumers like me, you and the lion in the zoo) break them down to release their energy for tasks their cells need to do (cellular respiration, catabolism). As time passes, all that energy is converted to heat and radiated from our bodies, and ultimately by the atmosphere off the Earth (barring excessive greenhouse gases.)

Third question: Not necessarily. If the multi-cellular organism were a closed system, you are absolutely right. The chemical energy would rapidly be all converted to thermal energy, and the order would disappear entirely. However, bodies are not closed systems: they are continually radiating thermal energy and absorbing chemical energy, either from the sun through photosynthesis, or from autotrophs through ingestion and digestion.

A picture is worth 1,000 words:

(Image courtesy of stephsnature.com)

• I would hope this picture is worth more than 1000 words, since that's only about 2 pages of single-spaced text. =P – Charles Oct 20 '17 at 18:50
• Some pictures may be worth 1000 words, but imho this is completely meaningless, either on its own or in relation to a question on entropy. Doesn't even make good wallpaper. – David Oct 21 '17 at 0:21
• @David, I thought the image was fairly self-explanatory, but maybe not, lol. The point is that the energy coming into the system is in the form of light, the energy going out of the system is heat. As I said in the post, heat is the energy form with the highest entropy. Therefore, though the entropy in the system is not necessarily increasing, the energy outside the system necessarily is. Please ping if you want more clarification. – rotaredom Oct 23 '17 at 12:01