A physical factor that influences an ecosystem is called an "abiotic factor."
Molecules are defined as the smallest particles of a chemical compound or an element, and are made up of atoms. Cells are made up of semi permiable membranes that only allow selected materials to move in or out of the cell, therefore due to the big size of molecules compared to atoms the membrane doesn't allow their passage in the cell. Therefore the cell doesn't allow most molecules to diffuse passively to the cell. Secondly, molecules that can enter the cell requires specific carriers carriers that will enable entry of small molecules in the cell.
The mutation will occur on the X chromosome. Males are more susceptible to sickle cell amenia because they only carry one X chromosome instead of two when compared to a set of female chromosomes. If a female only has the mutation on one chromosome the disease will not appear. However, when a male recieves the mutation on the X chromosome, the disease would appear, because they only have one X chromosome.