A cell will only freely allow in very small molecules such as oxygen, water and carbon dioxide. Larger molecules such as sugars must be transported into the cell through special channels using energy.
The Cell membrane on a plant cell is used to allow some substances into the cell (for nourishment) while keeping other (harmful or unwanted) substances out.
they allow some substances to come in and out of the cell. this is because they are semipermeable.
The cell membrane allows the passing of some substances.
allow substances in and out of the cell.
Aquaporins allow water molecules to pass through cell membranes.
You could be referring to the cell membrane or carrier proteins. Both allow certain substances to enter cells.
The cell membrane controls what substances enter and leave the cell and at what rate it also separates the inside of the cell from its surroundings keeping the contense of the cell together and concentration gradients in place and don't forget it also contains receptors which allow messages to be convayed to cells.
cappillaries
Projections that allow the cell to move or to move substances along the surface of the cell are called cilia and flagella. Flagella is a single long hair that allows the cell to swim. Cilia are several projections used for movement across the cell surface.
Channel proteins are a type of protein found in the cell membrane that regulate the passage of specific ions or molecules into or out of the cell. These proteins form channels or pores that allow substances to pass through the membrane, controlling the movement of substances across the cell membrane.
If there were no Golgi apparatus, or Body, then the Cell would not be able to fully produce new substances because the cell would not be able to "package" substances such as enzymes etc. into secretory vesicles or micelles which attach to cell walls and allow the substance to leave the cell. by-ArindamJjain IX-A
Protein channels in the plasma membrane act as gateways that allow specific substances to pass through, regulating the movement of molecules in and out of the cell. These channels are selective, meaning they only allow certain substances to pass through based on size, charge, or other characteristics. This helps maintain the cell's internal environment and allows for the efficient transport of essential molecules.