Why is Carbon instead of silicon, "the building block of life"

[Dallin]

I have an assessment task requiring me to identify why "carbon instead of silicon, is the "building block of life". I have formulated a few ideas about this, such as, Carbon is better because in Earths premortial state (slime and whatnot) billions of years ago, the energy required to make carbon would have been less than that required to make silicon. This can be attributed to Carbon having a smaller nucleus, therefore, less protons, neutrons and electrons. And we all know that everything likes to have a low energy level to remain as stable as possible (which isn't to say that silicon has a higher energy level, as it has 4 valence electrons also, meaning similar properties). And well, it is no surprise that Carbon would have been made either before silicon or atleast in greater abundance than silicon, making it available for life forms to use as an energy source.

 

I am thinking maybe density also??? Organisms would rather use something lighter to obtain energy...I am not sure as to whether them using silicon instead would use more energy????? (just throwing ideas out there lol) because if this was the case, than it can be somewhat related bac to the 'lac operon' system, if there is glucose and lactose present, than the cell will use all the glucose first before using extra energy to break the lactose to obtain its energy....again, as i mentioned, i am just throwing ideas around

 

Any feedback or new ideas regarding this topic would be greatly appreciated.

 

Thanks.

[insane_alien]

carbon was not made in the early slimes. it was made in the star that formed the nubula the solarsystem condensed out of.

 

but basically what you are saying(more stable forms preffered) is correct, but for the wrong reasons.

 

i would recommend you look up information on various silicon molecules that are similar to carbon based molecules(say silane instead of methane) and see what happens when they are exposed to air. then you'll know why silicon would be useless.

[swansont]

Also look and see if there are molecules where it isn't possible to just replace a carbon with a silicon, and why. And whether the enthalpy of any necessary reactions changes sign when you use a silicon-based molecule instead of carbon.

[insane_alien]

another thing to look up is the resipiration products, we breath out carbon dioxide, have a look at silicon dioxide(or through it *hint hint*) and see what problems could arise

[CharonY]

That would not pose a problem for anaerobic respiration, though.

[insane_alien]

ah cracks in my biology showing through there.