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Good morning.
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Today we are going to study about particle size and membrane transport.
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The first type of membrane transport is diffusion.
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In diffusion, the particles, that is the smallest particles are transported directly through the membranes and some example of these particles will include carbon dioxide, hydrogen, oxygen, sugar and so on and they freely diffuse across the membrane based on the concentration gradient across the membrane and for which no energy is needed.
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The second type of membrane transport is through membrane channels.
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Membring channels are nothing but they are made of proteins that are present on the surface of the membranes or through the membranes.
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It will transport small particles like for example water, sugar, sodium, calcium, potassium, so on.
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And these small molecules are transported not only based on their concentration gradient, but it also needs energy for the transport.
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The third type of membrane transport is through phagocytosis.
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In phagocytosis, particles that are larger than 0 .5 micrometer are transported across the cells and for this transport membrane vesicles are formed which are by surrounding the foreign particles or these 0 .5 micrometer larger particles that are engulfed and processed into the cell or transported into the cell as small vesicles where they are digested and eliminated so this is a cleanup process where unmoved wanted particles like foreign particles, microbes, pathogens, dead cells are removed from the body.
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The last type of membrane transport is endocytosis.
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Endocytosis is rather an umbrella term which involve different types of membrane transport like phagocytosis, pinocytosis, and clathrin, mediated endocytosis.
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In endocytosis, the process is more or less similar to phagocytosis where the membrane form vesicles or they engulf the foreign particles with and by surrounding it and form vesicles to transport it into the cell and they are eliminated or processed accordingly inside the cells.
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And the particles that are transported in endosite, they are eliminated or processed accordingly inside the cells.
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Endocytosis will be as small as 10 nanometers to as large as 5 micrometers...
