how do substance enter cell membrane?

Answer 1

There are two ways: active transport and passive transport. The principle means of passive transport is diffusion. Osmosis is a special case of diffusion.

Active transport include protien pumps, endocytosis, and exocytosis.

Answer 2

There are several methods by which substances can cross the cell membrane.

First, substances can be passively diffused directly across the cell membrane due to a concentration or electrochemical gradient. Osmosis is the special diffusion of water down its concentration gradient

Second, substances can participate in facilitated diffusion in which a special carrier molecule transports the substance across the cell membrane. The function of several proteins, either as ligand-gated or voltage-gated channels serve this purpose.

Third, substances can be actively transported across the cell membrane. This process requires an expenditure of energy (ATP) to push substances up their concentration gradient. An example of this is the Na-K ATPase pump which exchanges two potassium molecules for three sodium molecules to maintain the concentration gradient needed for cells to generate action potentials.

Answer 3

Since the cell membrane is semi-permeable, only a few substances are allowed to enter. They enter through tiny spore-like holes in the membrane. But in order to allow all substances to enter, the cell must be placed in hot water so all processes can stop and the membrane can expand. If it expands too much, it will break and the water would rush in.

Answer 4

There are locks and keys just like a house and car, if let's say a virus has those keys they can enter the cell membrane.

Answer 5

authentic. Plasma membrane is a selective membrane. yet, are not getting plasma membrane tousled with cellular wall. Plasma membrane isn't the cellular wall. cellular wall is the membrane that covers plasma membrane in plant cells. there is not any "cellular wall" in animal cells. Plasma membrane is cutting-edge in both animal and plant cells. It determines what's gonna flow by itself. desire this enables :)

Answer 6

the cell membrane is SEMI -PERMEABLE i.e only selected items can pass through the membrane into the cell.

some of these items include respiratory gases such as oxygen, carbon dioxide, dody wastes and even hormones