Unit 3 terms Flashcards
What is diffusion?
The movement of a solute from an area of high concentration to an area of low concentration .
Passive transport..
..requires no energy input from the cell (moves down the concentration gradient)
What is active transport
The movement of molecules from an area of low concentration to an area of high concentration. It requires active energy input from the cell.
What powers active transport?
Cellular energy, which is generated in the mitochondria.
What is endocytosis?
A type of active transport which moves large molecules into the cell.
The cell membrane changes shape and surrounds and engulfs the particle to form a vesicle which is transported into the cell to become part of the cytoplasm.
What is exocytosis?
The active transport of substances out of a cell against a concentration gradient.
What is a vesicle?
A vesicle is a self-contained structure consisting of fluid or gas surrounded and enclosed by an outer membrane
What are the three ways in which endocytosis occurs?
Pinocytosis (The entrance of liquid cells)
Phagocytosis (The entrance of solid cells)
Receptor-mediated endocytosis (The entrance of selected molecules specifically required for the cell. e.g. hormones)
How does exocytosis occur?
Vesicles in the cytoplasm fuse with the cell membrane and expel their contents to the outside of the cell.
What do transport proteins (channels) do?
They allow facilitated diffusion to occur, which allows molecules to move more passively down the concentration gradient.
What are cell membranes made of?
A phospholipid bilayer
What is a phospholipid bilayer?
A double layer of phospholipids, which are made up off hydrophilic phosphate heads an hydrophobic fatty acid chains.
