Ameboid Locomotion of the Cell
Ameboid locomotion is the movement of an entire cell in relation to its surrounding.
Mechanism of Ameboid Locomotion
Moving the Cell Membrane
At rear end of the cell…
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endocytosis
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Shrinkage of cell membrane, and formation of endocytotic vesicle
↓ The vesicle is transported to the leading end of the cell
↓
Inserted on the cell membrane by exocytosis
↓ Cell membrane expands at leading end
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Formation of pseudopodeum
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Receptors on the cell membrane attach the cell firmly to the new area.
Moving the Cell Body
In the pseudopodium, network of actin and actin-binding proteins such as myosin is synthesized
↓ This network contracts
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Pulls the cell body towards pseudopodium
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Thus the entire cell moves
Control of Ameboid Locomotion: Chemotaxis
Chemotactic Substance
Direction of movement is guided by chemicals called chemotactic substance.
Its concentration is higher near its source, and it gets lower away from the source.
The cell detects this concentration difference and decides which direction to move to.
Positive chemotaxis
The cell moves toward the higher concentration of the chemotactic substance i.e. towards the source of chemotactic substance.
This is more common.
Negative chemotaxis
The cell moves away from the source.
It's less common.
Cells Showing Ameboid Movement in the Body
White Blood Cells: To move from blood vessels to tissue.
Fibroblast: To move to the damaged area for repair.
Embryonic Cells: To spread the cells developed new tissues, organs, etc.