Question

Due to the fact that we possess enzymes that break down the alpha linkages in starch, the glucose molecules that make up amylose and amylopectin are available for humans to absorb. The beta linkage that bonds glucose in dietary fiber products such as cellulose is not available to humans because we do not possess the enzyme capable of breaking down the beta bond.
A. True
B. False

Answer 1

The answer is: A. True

Complex sugars or polysaccharides are composed of basic units called monosaccharides that are linked via  glycosidic bonds. Glycosidic bond is formed through condensation reactions (water is released) that occur between a hydroxyl (OH) oxygen atom on one sugar and the α-anomeric form of C-1 on the other. There are are two types of glycosidic bonds:

- 1,4 alpha ( the OH is below the glucose ring)

- 1,4 beta glycosidic bonds (the OH is above the glucose ring)

Amylase is an enzyme that breaks down starch into smaller glucose molecules, it act on α-1,4-glycosidic bonds and it works in mouth where the digestion begins (salivary amylase) . Maltase breaks down maltose into glucose; sucrase, breaks down sucrose into glucose and fructose; and lactase, which breaks down lactose into glucose and galactose work in small intestine and also act on α-1,4-glycosidic bonds.