Facilitated diffusion, a form of passive transport, is the process that allows sugars to enter cells. Scientists also refer to this process as facilitated transport. During the process, glucose crosses the cell membrane.
About.com says that glucose is unable to pass through the lipid layer of the cell wall, due to the hydrophobic nature of the lipids, although small molecules such as oxygen are able to pass easily. Sugar molecules pass through proteins that form transmembrane channels. These channels have gates that open and close, allowing selected molecules through the cell walls. Carrier proteins transport the larger molecules, including glucose and amino acids. Closing these gates protects the cell from disease and potential danger.
According to HowStuffWorks, all the processes the cell carries out require energy. Generating energy is a basic process of all cells. It is generated by rearranging glucose molecules by controlled oxidation or cellular respiration. Plants, bacteria and algae create the carbohydrates they need for cellular respiration through photosynthesis, transport them to the cells and oxidize them for energy. Animals, as well as some bacteria and certain protists, are unable to produce carbohydrates and depend on their environment for this energy supply. Once the cell releases the energy from glucose, it stores it in the bonds of ATP.Learn More
Facilitated diffusion is a form of passive transport that utilizes transport proteins. These transport proteins are embedded within cell membranes, serving as figurative highways for molecules to get in and out of the cell.Full Answer >
Simple diffusion and facilitated diffusion both allow molecules to cross the cell membrane without any expenditure of energy by the cell. They are each classified as a type of passive transport.Full Answer >
Diffusion is the action of molecules moving from an area of high concentration to an area of lower concentration. It is caused by kinetic energy.Full Answer >
If the cell membrane becomes totally impermeable, water and dissolved gases, most notably oxygen, would no longer be able to enter or leave the cell. The cell membrane is usually permeable to a number of substances, mostly small, nonpolar molecules. Other polar or charged particles are transported across the membrane by special embedded protein structures, and so would not be directly affected by a change in membrane permeability.Full Answer >