Question

how would you describe the measure of entropy in an organism

Answer 1

This is an incredibly difficult problem. Is there any more specific way you could state the question, perhaps...?

Answer 2

I guess you could measure it in the time it takes for entropy to become apparent. For example weeks, or years for a "symptom" or another indication of entropy setting it. Entropy has been compared to an "arrow of time." Meaning once it starts it proceeds in one direction and cannot be reverse. How fast it progresses is important and there is a formula, several actually that can be used. But essentially they look at factors affecting the time of the entropy. Narrowing it down can allow changes to be made to slow down the progression of the entropy, however as I previously stated it can never be reversed.

Answer 3

It depends on how you define entropy, but in practical terms (like those relevant in a biologic system), I'd say it can be reversed.

When I think about entropy, I think about in context of an untidy room. Of course it tends toward disorganization over time and the rate at which it tends toward untidiness is determined by the nature of the person living in it. But with input of energy (i.e., cleaning), it is possible to reverse the trend and turn an untidy room into a clean one.

Same with cells and living organisms: the trend toward disordered and high entropy states is energetically favorable - and cells and living organisms spend a great deal of energy countering this trend.

Fascinating discussion, though - your perspective on it, MathsBlonde?

Answer 4

I think it depends on how you look at it. Like a room yes, it appears that entropy can be reversed. Perhaps at a cell level or even the organ level. But looking at the systems level it becomes much more complicated. Looking even larger at the entire organism. The reality is entropy starts say...mid aged....earlier really. Like mid to late 20s. Aging has started...entropy...has started. Cells begin to have more errors and disorganization results from it. Compare the overfed cell to the underfed cell and using the theoretical Hayflick limit. Once this overfed cell has replicated 50+ times it can no longer replicate. This can lead to apoptosis, senescence, or simple an "old" metabolically active cell. The underfed cell will have replicated slower however and still have lots of life left and with that means more chances to find and fix errors. Does that make sense? @blues

Answer 5

I would say that the age of the organism has no real effect on its level of entropy or disorder.

Cells definitely accumulate random mutations and some of these mutations are definitely due to random and stochastic structural fluctuations between the bonding atoms in the DNA.

In the first place these random and stochastic structural fluctuations do not necessarily correlate with an increase in molecular disorder or entropy. In as much as they change the nature of a highly ordered state to another highly ordered but inappropriate one - yes, you could class that as entropic change. Though the people heavily into thermodynamics might not be so easily convinced of that as I.

And in the second place, all these cells expend a great deal of energy checking for and repairing mutations when they happen. In most cases, they fix it. So like cleaning the room, with input of energy they do reverse the mutation accumulation process.

There are other, more ordered mechanisms of aging than simple entropic change - most of these are highly deterministic and involve low levels of entropy. Epigenetic change, for example. And oxidative damage.

Answer 6

Nor is entropy necessarily bad. I guess I see it as a balance - with some entropic energy driving otherwise unfavorable processes like protein folding.

The highly ordered protein state has a low entropy - but it frees up water molecules which would have otherwise H bonded with the unfolded peptide to form water cages and other very low order (i.e., high entropy and energetically favorable) structures with each other. The increase in entropy of the water molecules is greater than the decrease in entropy of the protein. So the whole overall process is energetically favorable.

So entropy is a necessary component of all biologic systems (healthy ones, young ones, unhealthy ones, old ones) with out which life would be completely static and dead.

Answer 7

Try to think of entropy as a measure of the possible states of a system. For example, if you were to ask yourself which has more entropy, ice or liquid water, you could reason that the molecules in the liquid state are relatively free to move and rotate, whereas in ice the molecules are "frozen" in fixed positions, with little movement except for the vibration of the bonds. So for water, there are much more orientations possible for each molecule, resulting in a multitude of possible states for the liquid solutions.

Another example to contemplate is the mixing of two liquids such as acetic acid and water. If acetic acid is poured into water, the acetic acid molecules will spontaneously disperse themselves evenly throughout the solution, and will not stay bunched together and separated from the water. This is because, in the case where the two remain neatly separated, the situation is much more ordered (less random), and the natural tendency is for randomness (entropy) to increase.