The properties of the original elements are completely changed.
For example, in the compound called "iron(II) sulphide", it is composed of iron and sulphur, that are chemically combined together. The element iron is attracted to magnets. Meanwhile, iron(II) sulphide is not attracted to magnets. 
Another example is where sulphur has a yellow colour, but iron(II) sulphide has a brownish colour. As we can see, even the physical properties (colours) are completely different.
Therefore, the properties of the original elements are completely changed when they're combined into compounds.
        
             
        
        
        
Common examples of this would be if you place your hand in extremely warm or cold water, and an immediate response of pulling out of the water or any fluid, is an example of this extreme response, other responses are what is done in everyday, like being thirsty or hungry etc. 
These behaviours are shared by all organisms even the most simple ones.
        
             
        
        
        
DNA and RNA both produce proteins, but RNA copies itself and moves out of the nucleus while DNA stays inside the nucleus and produces proteins. Also DNA helps more in cell division, while RNA helps in making proteins.
        
             
        
        
        
Im really good at crosswords, e-mail a copy & i’ll fill it out for you
        
             
        
        
        
Answer:
There are six of them, based on the common compound that they are synthesized
Explanation:
The family of L- glutamate come from the cetoglutarate compound from the Kreps cycle. The family of L-serine, come from 3 - phosphoglicerate compound from the glucolisis. The L - aspartate family, that come from oxaloacetate compound, from the Krebs cylce. The piruvate family that come from the piruvate, from the glucolisis. The aromatic aminoacids, that come from eritrose - 4 - phosphate, from the pentose cycle. And the L histidine family, that come from the ATP.