Can you count the protein used to cook with?

[huneypie]

Note how the process is somewhat like how an economy works, in that ATP is like energy currency.

It generally requires energy to force two molecules to react (to make two amino acids link together) because Nature prefers randomness rather than structure. ATP (adenosine triphosphate) stores a lot of energy in the bond between the second and third phosphate group when it is synthesized - when you break that bond to form ADP (adenosine diphosphate) and a phosphoric acid, energy is given off that can be used to drive a reaction that has to be "forced" to happen, usually making a bigger or more highly ordered molecule from a simpler one.

So, what happens when you break down bigger molecules to smaller ones, is that these kinds of reactions happen with the help of an enzyme that ties the breaking of a chemical bond from the bigger molecule (like the starch to a sugar, or a protein to an amino acid), to driving the synthesis of a molecule of ATP from ADP - pretty much conserving the energy that was used to make the bigger molecule in the ATP molecule. Then that ATP molecule can be used anywhere in the cell to drive a synthetic reaction that needs energy to make it happen.

The acetyl-CoA is kind of like a very small brick (it is a 2 carbon unit with an oxygen and 3 hydrogens) that can be used in many many biosynthetic reactions to build larger molecules, including sugars, fats, and proteins.

In the bigger picture, acetyl-CoA can also be fully catabolized down to carbon dioxide and water, to capture extra energy in the form of ATPs. And - to complete the cycle, all of this energy ultimately comes from the sun: photosynthesis is the process by which energy from the sun is used to - yes, you guessed it! - capture carbon dioxide from the air, to produce small carbon building block molecules inside plants, which use them to make sugars, starches, fats and protein (as well as giving off a portion of the dioxide as oxygen):

And that's pretty much summarizes the biology of metabolism.

Wow, I think something like Surgeon General would be more appropriate than Bad Cop

 

[Taterweight]

The no more than 5 images is to rein in the smilies, @DianaCox !

Booooo!!

 

[Barb1]

Hell I give up! I must be about 6 years old. I even spelled boggles wrong again the second time.

 

[MsBatt]

A most excellent explanation, Diana! I hope you don't mind that I coped this for future reference.

 

[Spiky Bugger]

@MsBatt

 

[DianaCox]

An attempt at a simpler explanation ...

PLANTS: Energy of the sun + carbon dioxide + water -> carbon, oxygen and hydrogen being rearranged into bigger molecules (carbohydrates [including sugars], protein and fat in plants (plus excess oxygen released into the atmosphere). (Nitrogen needed for protein is absorbed from the soil; that nitrogen comes from the air, and bacteria that live in the soil at the plant roots convert the nitrogen from the air into a chemical form [nitrate] that the plant can absorb through the roots.)

Energy from the sun drives the reactions that build these complex molecules from simple carbon dioxide. That energy is stored in the chemical bonds between the "subunits" (amino acids that make up protein; sugars that make up carbohydrates; acetyl-CoA that makes up fats).

ANIMALS: Cows/pigs/fish eat plants, and convert the carbs/fats/proteins (mostly carbs) into THEIR muscle proteins. They do this by breaking down the plant proteins, carbs and fats to subunits - recycling both the subunits and the energy given off by breaking the bonds (saved by the ATP), and then using energy saved in the ATP that is created when the plant stuff is broken down to drive the reactions that need energy to synthesize NEW proteins, carbs and fats that make up the animal.

HUMANS: Of course, we eat both plants and animals, and do the same thing - catabolize their proteins/carbs/fats into subunits, save the energy as ATP, and use the ATP to rebuild the subunits into human proteins/carbs/fats.

Of course, there is ALWAYS an excess of food taken in over that which is needed to break down our food components and rebuild them into human versions, because we ALSO need a lot of energy to power our muscles (and brain) and to keep us warm. The excess food is broken down COMPLETELY to acetyl-CoA and then FURTHER broken down to ATP and carbon dioxide (hello plants - we are giving it back to you!) - and the ATP is what is used to power our muscle contractions, to fire the electricity of our brain/nerves, and some of the energy of the ATP is deliberately "wasted" to generate heat.

Carbon-containing food (stored energy in the chemical bonds) + oxygen -> carbon dioxide (what we exhale) + water (pee) + the energy used to run and heat our bodies.

The organelles in our cells that manage this energy metabolism, the mitochondria, are exquisitely-well regulated (and are bacterial in origin!). Hibernating animals store significant deposits of fat before they hibernate; they have a special type of fat called brown fat, because they have more mitochondria (which have colored proteins in them) which deliberately are not "energy-efficient" - they are capable of breaking down the fat with the intent to "waste" much of the energy stored in the fat in the form of heat to keep the animal warm (and alive), while providing just enough energy and subunits of acetyl-CoA to keep the animal's organs alive while it hibernates.

We are born with a significant amount of brown fat, which is used by babies to keep their temperatures stable. As we get older (and have a higher volume:surface area ratio, and thus are easier to keep warm), we lose our brown fat, and become more efficient at storing any excess energy we take in as white fat.

Interestingly, people who are thin, and who seem to stay thin no matter how much they eat, generally have more brown fat than those of us who get obese. And if you measure the temperature over their brown fat deposits (mostly on the back), you will see that when they take in too many calories, instead of STORING them (like we, the efficient, famine-survivalists do), they "waste" excess calories in the form of heat, dissipated off their backs. And that's how they stay thin. Entitled assholes that they are.

 

[Whit]

Can we book mark this? Very interesting.

 

[southernlady]

Can we book mark this? Very interesting.

Bookmark, no BUT you can watch the thread.

 

[Hala]

Note how the process is somewhat like how an economy works, in that ATP is like energy currency.

It generally requires energy to force two molecules to react (to make two amino acids link together) because Nature prefers randomness rather than structure. ATP (adenosine triphosphate) stores a lot of energy in the bond between the second and third phosphate group when it is synthesized - when you break that bond to form ADP (adenosine diphosphate) and a phosphoric acid, energy is given off that can be used to drive a reaction that has to be "forced" to happen, usually making a bigger or more highly ordered molecule from a simpler one.

So, what happens when you break down bigger molecules to smaller ones, is that these kinds of reactions happen with the help of an enzyme that ties the breaking of a chemical bond from the bigger molecule (like the starch to a sugar, or a protein to an amino acid), to driving the synthesis of a molecule of ATP from ADP - pretty much conserving the energy that was used to make the bigger molecule in the ATP molecule. Then that ATP molecule can be used anywhere in the cell to drive a synthetic reaction that needs energy to make it happen.

The acetyl-CoA is kind of like a very small brick (it is a 2 carbon unit with an oxygen and 3 hydrogens) that can be used in many many biosynthetic reactions to build larger molecules, including sugars, fats, and proteins.

In the bigger picture, acetyl-CoA can also be fully catabolized down to carbon dioxide and water, to capture extra energy in the form of ATPs. And - to complete the cycle, all of this energy ultimately comes from the sun: photosynthesis is the process by which energy from the sun is used to - yes, you guessed it! - capture carbon dioxide from the air, to produce small carbon building block molecules inside plants, which use them to make sugars, starches, fats and protein (as well as giving off a portion of the dioxide as oxygen):

And that's pretty much summarizes the biology of metabolism.

Show off... we know you are smart...(IT is a good thing BTW)

 

[DianaCox]

I just remember how I felt when I realized how beautifully symmetrical the process is, and how the energy of the sun drives the whole thing - and how fascinating it is that the energy that is captured by plants is transferred to the animals that eat them, and the animals that eat the other animals by using ATP as energy "currency" -it is made when bonds are broken, and it is used up to drive the formation of new bonds. Nature is amazing - and it's fun explaining it!