Technically the brewing of beer by ancient civilizations is a synthesis. Making Wine as well. So ancient Greeks, Romans, and Egyptians (as well as many others) synthesized alcohol.
The alchemists, although they had no real chemistry understanding, were also synthesizing some things.
In the 1800's after chemistry as a science of experimentation became more accepted, many substances were synthesized. One of the most notable was in the 1820's when Wohler synthesized urea proving that allorganic chemicals did not have to come from nature. Earlier (date unsure) in the late 1700's/early 1800's Cavendish burned pure hydrogen gas and synthesized water. He did not publicize his findings but later these were repeated by Lavoisierand most give Lavoisier the credit instead of Cavendish. Most don't call this a 'synthesis' but just a proof that water is a compound of hydrogen and oxygen. Bayer made aspirin (and a fortune).
organic
absorbed,released
Rough Endoplasmic Reticulum
New organells are formed.Proteins and DNA are synthesized efficiently.
Golgi apparatus
Vitamin D is synthesized when modified Cholesterol molecules. . .
Vitamin D is synthesized when modified Cholesterol molecules. . .
Cholesterol
organic
absorbed,released
Rough Endoplasmic Reticulum
New organells are formed.Proteins and DNA are synthesized efficiently.
Main products are ATP and NADH.Oxygen is a bi product.
Golgi apparatus
Because macromolecules are large molecules and are insoluble. It is easier to store them and use them when they have been hydrolysed to smaller molecules and are made soluble.
Billions, but what needs attention are the trillions of unneeded molecules that are 'automatically' excluded from the cells of living organisms.
Rough ER (Endoplasmic Reticulum)