Active Transport Flashcards
What is active transport?
movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration
this process requires energy and carrier proteins as molecules are being moved up a concentration gradient
How does a molecule enter a cell through active transport?
1) the molecule or ion to be transported binds to receptors in the carrier protein
2) inside the cell, ATP binds to the carrier protein and is hydrolysed into ADP and phosphate
3) binding of phosphate molecule to the carrier protein causes the carrier protein to change shape, this opens up the inside of the cell
What happens after the molecule has entered the cell?
the phosphate molecule is released from the carrier protein and it recombines with ADP to form ATP
the carrier protein returns to its original shape
What is bulk transport?
for large molecules such as enzymes or hormones that are too large to move through the channel or carrier proteins
What is endocytosis?
bulk transport of materials into cells
2 types phagocytosis for solids and pinocytosis for liquids but the process is the same for both
What is the process of endocytosis?
the cell-surface membrane invaginates when it comes into contact with the material being transported
the membrane enfolds the material until the membrane fuses, forming a vesicle
the vesicle pinches off and moves into the cell
What is exocytosis?
the reverse of endocytosis
vesicles move towards and fuse with the cell surface membrane
the contents of the vesicle are then released outside of the cell
What is required to move the vesicles?
energy in the form of ATP is required for:
the movement of vesicles along the cytoskeleton
changing the shape of the cells to engulf materials
the fusion of cell membranes as vesicles form or as they meet the cell surface membrane
What happens when the vacuole after it fuses with the lysosome?
break donw the substance so the protein molecules can be used
breaking peptide bonds
creating soluble amino acids
