What are the main ways of material transport in cell membranes?

There are four kinds. 1) Simple diffusion: The phenomenon of fat-soluble small molecule substances or ions moving from the high concentration side of the membrane to the low concentration side is called simple diffusion.

Factors influencing pure diffusion:1concentration difference on both sides of the membrane; 2.

Permeability of the membrane. The characteristics of simple diffusion are: it does not need the help of membrane proteins, does not consume the cell's own metabolic energy, and proceeds along the concentration difference.

Substances transported by simple diffusion: fat-soluble small molecule substances, such as CO2, O2, N2, NO, etc.

ii) Facilitated diffusion: refers to the transport mode in which water-soluble small molecule substances or ions move from the high-concentration side of the membrane to the low-concentration side of the membrane with the help of membrane proteins. Types of Facilitated Diffusion:

1) Carrier transport: refers to the facilitation diffusion completed with the help of carrier proteins. Features of vector transport:

1.specificity; 2.saturation; 3.

Competitive inhibition. Carriers transport and transport substances: mainly water-soluble small molecule organic substances, such as glucose and amino acids.

2) Channel transport: refers to the facilitation diffusion completed with the help of channel proteins. Classification of channels:

voltage-gated channels; chemically gated channels; Mechanically gated access. Substances transported by channels: mainly inorganic salt ion substances, such as Na+, K+.

Factors influencing facilitated diffusion:1concentration or potential difference between the two sides of the membrane; 2.

Number of vectors and functional status of channels. The characteristics of facilitated transport: it needs the help of membrane proteins, does not consume the cell's own metabolic energy, and proceeds along the concentration difference.

3) Active transport: refers to the transport of substances from the low-concentration side of the membrane to the high-concentration through the energy dissipation of the cell itself under the action of the biological pump on the cell membrane. Active Transporting Substances in Transshipment:

Mainly ionic substances such as Na+, K+, Ca2+. Characteristics of active transport: it requires the action of a biological pump to digest the cell's own metabolic energy, and proceed against the concentration difference.

Factors influencing active transport:1the functional status of the biological pump; 2.

The metabolic level of the cell.

4) Cytokinesis and cytokinesis: The migration of macromolecular substances from the inside of the cell to the outside of the cell is called cytokinesis. The migration of macromolecular substances from the outside of the cell to the inside of the cell is called cell entry.

Substances transported in and out of cells: macromolecular substances such as transmitters, hormones, digestive enzymes, bacteria, tissue necrotic fragments, senescent red blood cells. Characteristics of outgoing and incoming:

The movement of the cell membrane is required, which consumes the cell's own metabolic energy.

Simple diffusion (no carrier required): oxygen, nitrogen, carbon dioxide, ethanol, urea, etc.

Membrane protein-mediated transmembrane transport.

Passive transport. Facilitated diffusion by carriers: glucose, amino acids, nucleotides, etc.

Facilitated diffusion through channels: K ions, Na ions, Ca ions, Cl ions, etc.

Active transshipment. Primary active transport: inverse concentration gradient or potential gradient transport of various ions.

Secondary active transport: Na-H ion exchange, Na-Ca ion exchange, etc.

Both passive and active transport are included.

Differences:

Passive transport is further divided into: free diffusion and assisted diffusion.

Passive transport is the transport of substances from high to low concentrations.

Carriers for transport are also needed to assist in proliferation.

Active transport is from low concentration to high 8 concentration, which requires both carrier and energy.

The cell membrane is mainly an elastic semi-permeable membrane composed of phospholipids, and its main function is to selectively exchange substances, absorb nutrients, discharge metabolic wastes, secrete and transport proteins. The modes by which cell membranes transport substances include passive transport, active transport, endocytosis, and exocytosis.

The diffusion of substances in and out of cells is along the concentration gradient, called passive transport, and includes both free diffusion and assisted diffusion.

1) Free diffusion: Substances enter and exit cells through simple diffusion, which is called free diffusion.

2) Assisted diffusion: The material entering and leaving the cell borrows the plate to assist the diffusion of carrier proteins, which is called assisted diffusion.

Transport from the side of low concentration to the side of high concentration requires the assistance of carrier proteins, as well as the consumption of energy released by intracellular chemical reactions, a method known as active transport.

Exocytosis and exocytosis are the weights of macromolecular particulate matter in and out of the cell.

Answer: The transport of substances by the cell membrane includes the following two aspects.

1. The way in which small molecule substances and ions enter and exit the cell is selected is based on the functional characteristics of the cell membrane: permeability. It includes active transport, free proliferation, and assisted proliferation.

2. The way in which the selected macromolecule enters and exits the cell is based on the structural characteristics of the cell membrane: fluidity. It includes both endocytosis and efflux.

Simple diffusion, assisted diffusion, active transport, and endocytocytosis are the four modes of material transport in the cell membrane. The main functions of cell membranes are to selectively exchange substances, absorb nutrients, excrete metabolic wastes, and secrete and transport proteins.

1. Simple diffusion: the diffusion process of fat-soluble substances from the high-concentration side to the low-concentration side of the membrane is called simple diffusion. No energy consumption, no carrier required. Such as: water, urea, carbon dioxide, etc.

2. Assisted diffusion: The process of transmembrane diffusion of non-fat-soluble substances with the help of membrane proteins along the concentration difference or potential difference is called assisted diffusion. It does not consume energy, but requires a carrier.

3. Active transport: Under the action of the "pump" on the membrane, ions or small molecules are transported across the membrane by the reverse concentration difference or potential difference, which is called active transport (active transport). Active transport requires the consumption of a lot of heat and the need for carriers. Selectively permeable.

4. Endocytosis and cytocytosis: It is an effective way to transport macromolecules or agglomerates. The process by which a substance enters the cell from outside the cell through the movement of the cell membrane is called endocytosis.

Including phagocytosis and devouring. Liquid substances are swallowed and swallowed, such as the absorption of nutrients by the epithelium of the small intestine; The entry of solid matter into the cell is phagocytosis, as is the process by which granulocytes engulf bacteria.