Water molecules are allowed to pass through, but large molecules such as sucrose, starch, and protein are not allowed to pass through.

Including cellophane, casings, egg shell membranes, bladder membranes

Refers to the expansion of water molecules through a semipermeable membrane

condition

Osmosis

Including the cell membrane tonoplast and the cytoplasm in between

effect

Features

When the concentration of the external solution is greater than the concentration of the cell solution, plasmolysis will occur

Refers to the separation of protoplasm layer and cell wall

reason

free diffusion

aiding proliferation

Same point

difference

Transport of substances across membranes against concentration gradients Requires assistance from carrier proteins At the same time, it also needs to consume the energy released by chemical reactions in the cells. This method is called active transport

Thyroid follicular epithelial cells absorb iodine from the blood

Small intestinal epithelial cells absorb amino acids, glucose from intestinal fluid

Red blood cells absorb potassium ions from the blood

Chara absorbs potassium ions from the external environment

Ions or molecules bind to carrier proteins and are driven by energy Carrier proteins and structural changes Release transported molecular ions from one side of the cell membrane to the other Carrier protein returns to its original state specific

specificity

Binds to transported ions

saturable

Spatial structure changes during transport

reusable

Cystic fibrosis patient lungs Abnormal function of transport proteins on the surface of bronchial epithelial cells Increased mucus and bacterial infection

concept

Example

concept

Example

Notice

both require vesicle transport

All require the consumption of energy produced by cellular chemical reactions

All related to membrane proteins

All reflect membrane fluidity

Powered by ATP

Both transport across membranes, but across zero membrane

Derived from the electrochemical gradient of ions on both sides of the cell membrane

Carrier protein catalyzes the hydrolysis of ATP, causing the sodium ion concentration in the cell to be higher than that in the membrane

Potassium accumulation and sodium excretion

Carrier protein, catalyzes ATP hydrolysis