Concept of Movement of Substances Across a Plasma Membrane (3)

The movement of substances across a plasma membrane

Occurs through passive and active transport

Examples of passive transport

Simple diffusion, osmosis and facilitated diffusion

Simple diffusion (1)

Movement of molecules or ions from an area of high concentration to an area of low concentration, molecules move down the concentration gradient until a dynamic equilibrium is achieved

Simple diffusion (2)

Simple diffusion occur with or without the presence of a plasma membrane

Simple diffusion (3)

Lipid soluble molecules (fatty acids and glycerol), oxygen and carbon dioxide diffuse through the phospholipid bilayer as simple diffusion

Osmosis (1)

Is a passive transport process that is similar to diffusion but it involves only water molecules

Osmosis (2)

Refers to the net movement of water molecules from an area of high water potential to an area of low water potential randomly through a selectively permeable membrane

The selectively permeable membrane

Is permeable to water but impermeable to some solutes such as sucrose molecules

Facilitated diffusion (1)

The process of movement of lipid-insoluble molecules that are unable to pass through the phospholipid bilayer across the membrane with the aid of transport proteins (carrier or channel proteins)

Facilitated diffusion (2)

Facilitated diffusion does not require energy because the transport proteins transport molecules down a concentration gradient

Biology

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Concept of Movement of Substances Across a Plasma Membrane (3)

Concept of Movement of Substances Across a Plasma Membrane (3)