sodium ions, potassium ions

ion concentration difference

permeability

carrier protein

channel protein

1. Small molecular substances move along the concentration gradient or electrochemical gradient from the high concentration side to the low concentration side of the permeable membrane without consuming energy and without transport proteins. 2. Molecular size and molecular polarity determine the permeability. 3. Hydrophobic and uncharged small molecules can easily pass through

1. Along the concentration or electrochemical gradient, no energy is required, and membrane transport proteins are required 2. Polar small molecule inorganic ions enter and exit cells through assisted diffusion 3. Glucose transporter family 4. Aquaporins

Reverse chemical concentration differences, consume energy, and require carrier proteins

The two α catalytic subunits have ATP binding sites for phosphorylation and dephosphorylation. Two catalytic β subunits

Mechanism: 1. The intracellular α subunit binds to sodium to promote ATP hydrolysis. Phosphorylation of an aspartic acid residue on the α subunit causes a conformational change in the α subunit, pumping sodium ions out of the cell. 2. At the same time, extracellular The potassium ions bind to another site on the α subunit, dephosphorylating it, and the conformation of the α subunit changes again to pump potassium ions into the cell.

Function: 1. Maintain cell membrane potential 2. Maintain osmotic balance of animal cells 3. Absorb nutrients

1. Maintain low concentration of calcium ions in the cytoplasmic matrix 2. Pump into the sarcoplasmic reticulum to regulate the contraction movement of muscle cells

Plant cells, fungi, bacteria build hydrogen electrochemical gradients

A transmembrane domain composed of six α-helices forms a substrate transport pathway and determines substrate specificity.

ATP-active ATP-binding domain, convex toward the cytoplasm

ATP molecules bind to the ABC transporter, inducing two ATP structures and dimerization. The transporter conformation changes, and the substrate binding site is exposed to the cytoplasmic side of the plasma membrane. 2. ATP hydrolysis and adp dissociation lead to the dissociation of the ATP binding domain. The transporter returns to its original conformation

1. Exclude natural poisons and metabolites, which are abundant in the liver, kidney and small intestine. 2. Pump antibiotics and anti-cancer drugs out of cells, giving cells drug resistance. 3. Functional changes are related to some human genetic diseases, such as cystic fibrosis.

Phagocytosis

pinocytosis

Down-regulation: Endocytosis of epidermal growth factor and its receptors

Activation: Notch pathway

Continuous synthesis of proteins and lipids in the form of vesicles continuously supplies the plasma membrane for renewal, and soluble proteins are continuously secreted into the extracellular exocytosis pathway

Regulated exocytosis secretions are stored in secretory vesicles and fuse with the plasma membrane to release the contents when needed.

orderly transport of substances across membranes

Increase or decrease the area of ​​each area of ​​the plasma membrane to achieve dynamic balance, renew the plasma membrane and maintain cell survival and growth