A-LevelBiologyCell membranes and transport9700/12 · Oct/Nov 2014 · Q181 Mark
The enzyme lactase is found in the membranes of epithelial cells lining the small intestine. The enzyme is formed by a single polypeptide that folds to give three regions. • an active site with the free amino group outside the cell • a short section inside the membrane • a short section inside the cell What type of amino acid would be found in each of the three regions?
Aoutside cell: hydrophilic, inside the membrane: hydrophobic, inside the cell: hydrophilic
Boutside cell: hydrophilic, inside the membrane: hydrophobic, inside the cell: hydrophobic
Coutside cell: hydrophobic, inside the membrane: hydrophilic, inside the cell: hydrophobic
Doutside cell: hydrophobic, inside the membrane: hydrophobic, inside the cell: hydrophilic
✓ Correct answer
A: outside cell: hydrophilic, inside the membrane: hydrophobic, inside the cell: hydrophilic
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