1. What are anabolic & catabolic metabolism, & how do they relate to living organisms?

These 2 kinds of metabolic reactions are continuously occurring in living organisms. They are necessary for providing materials needed to maintain life.

Anabolic reactions are those which help cells grow & repair themselves by building larger molecules out of smaller ones. For example, complex sugars can be formed by bonding together smaller sugar molecules.

Catabolic reactions take apart larger molecules & reorganize them into smaller molecules. We could not make use of the nutrients in the food we eat if it remained in large molecules that are too large to be absorbed & taken into the blood stream.
 
 
 

2. What are some important anabolic & catabolic reactions?

Two major "building" & "taking apart" reactions are dehydration synthesis (an anabolic reaction) & hydrolysis (a catabolic reaction).

Example: When a disaccharide is formed by bonding 2 monosaccharides together, dehydration synthesis occurs. Dehydration refers to the removal of a water molecule, & synthesis refers to putting something together, or making something. In this example, as the two simple sugars (monosaccharides) are bonded together, the atoms needed to make a molecule of water are removed from the 2 sugars. Then a disaccharide molecule plus a water molecule are formed.

See Figure 4.1 for a diagram of this synthesis reaction
 
 

Example: When we digest food, the catabolic reaction called hydrolysis occurs. For example, when we eat a dissacharide, it is too large to be absorbed through the intestinal wall. The chemical bonds holding the disaccharide molecule together can be broken & the atoms of a water molecule separate & bond into the now available locations to form 2 separate simple sugar molecules. "Hydrolysis" refers to this process in which water (hydro-) split (lys-) the larger molecule into smaller parts.

See Figure 4.1 again, but this time read the diagram from right to left to see how hydrolysis is the reverse of dehydration synthesis.