Active Transport Flashcards
Active transport definition
The movement of molecules or ions into or put of a cell, from a region of a lower concentration to a higher concentration the process requires energy and carrier proteins, it requires energy from the movement of particles up a concentration gradient.
Define bulk transport
Bulk transport is another form of active transport, large molecules such as enzymes, hormones, and whole cells like bacteria are too large to move through channel or carrier proteins, they are moved in and out through bulk transport.
Endocytosis
The bulk transport of material into cells. There are two types phagocytosis (for solids) and pinocytosis (for liquid) they both use the same process.
How does the cell-surface membrane change due to endocytosis?
The cell-surface membrane first invaginates (bends inwards) when it comes into contact with the material being transported, the membrane enfolds from the membrane as it eventually fuses, forming a vesicle, the vesicle pinches off and moves into the cytoplasm to transfer the material for further processing in the cell. For example, vesicles containing bacteria are moved towards the lysosomes, they are digested by enzymes.
Exocytisis
Opposite of endocytosis. Vesicles are usually formed by the golgi apparatus, the contents move towards the cell surface membrane. The contents of the vesicke are then released to the outsides of the cell.
How does the material of vesicles move?
Energy in the form of ATP is required for the movement of vesicles along the cystoskeleton, changing the shape of cells to engulf materials and the fusion of cell membranes as vesicles form as they meet the cell-surface membrane.
