Describe how glucose may be obtained from maltose in a cell.
The digestion of carbohydrates starts in the mouth. The enzyme amylase breaks down starches into maltose, a disaccharide. In the duodenum pancreatic juice also contain enzyme amylase which proceeds with the breakdown of starch and glycogen into maltose, a disaccharide. The disaccharides are broken down into monosaccharides by enzymes called, maltases, lactases and sucrases. These enzymes are also present in the small intestines walls.
Enzymes maltases, breaks down maltose to glucose. Other disaccharides such as sucrose and lactose are broken down by sucrases and lactases respectively. Sucrose breaks down sucrose into glucose and fructose and lactase breaks down lactose into glucose and galactose.
The monosaccharide (glucose) produced is too large to dissolve through the membrane but there are integral proteins termed GLUT that utilize glucose concentration to move glucose in passively. Glucose in the GI tract can also enter the cell through secondary active transport, where sodium gradient inside the cell drives a trans-membrane protein to import glucose with it.