The diffusion process of water molecules (or other solvent molecules) from a place where the relative content is high to a place where the relative content is low through a semipermeable membrane

principle

Phenomenon

The cell membrane, tonoplasm and the cytoplasm between the two membranes are called the protoplasm layer. The protoplasm layer is equivalent to a semipermeable membrane.

Water leaching into plant cells mainly refers to the movement of water into and out of the vacuole through the protoplasm layer

The way substances enter and exit cells through simple diffusion is called free diffusion, also called simple diffusion.

It can only follow the concentration gradient (from high to low), does not require protein movement, and does not require energy.

The size of the concentration gradient of substances inside and outside the membrane. The greater the concentration difference, the faster the transport rate.

Following the concentration gradient requires the diffusion of substances in and out of the cell through transport proteins on the membrane. It’s called assisted diffusion, also called facilitated diffusion.

carrier protein

channel protein

It can only follow the concentration gradient (from high to low) and needs to operate proteins and does not require energy.

The size of the substance concentration gradient inside and outside the membrane The number of transport proteins

Transmembrane transport against a concentration gradient requires the assistance of carrier proteins and also requires the consumption of energy released by chemical reactions within the cell. This method is called active transport.

Absorb needed substances and excrete metabolites and substances harmful to cells

Sodium ions, potassium ions, calcium ions, etc.

Energy consuming, requires membrane proteins to participate in membrane-dependent fluidity

1. White blood cells phagocytes through endocytosis 2. Secrete proteins out of cells