2.3 - Cell transport Flashcards
Define simple diffusion
movement of molecules from area of higher concentration to area of lower concentration through a partially permeable membrane (phospholipid bilayer)
Define facilitated diffusion
movement of molecules from an area of higher concentration to an area of lower concentration through channel or carrier proteins
Define osmosis
movement of H2O molecules from an area of higher WP to an area of lower WP through a partially permeable membrane
Define active transport
movement of molecules from an area of lower concentration to an area of higher concentration using carrier proteins and energy released from ATP hydrolysis
Define co-transport
movement of 2 substances simultaneously from an area of lower concentration to an area of higher concentration using carrier proteins and energy released from ATP hydrolysis
Explain how channel proteins function and the molecules they transport
transport charged molecules (ions) which are dissolved as the channel contains H2O
Explain how carrier proteins function and the molecules they transport
transport large molecules by the binding of Pi to large molecule which enables it to bind to carrier protein
Describe the absorption of Na+ ions and glucose in the cells lining the ileum
- Na+ ions A.T. out of epithelial cell into blood
- establishes Na+ conc gradient between the ileum lumen and epithelial cell
- Na+ ions F.D from lumen down conc gradient into epithelial cell
- glucose/amino acids attach to co-transporter protein with Na+ ions and C.T into epithelial cell against their concentration gradient
- glucose F.D from the epithelial cell into the blood
How can cells be adapted for rapid transport across internal or external membranes?
- large SA
- lots of protein channels
- lots of carrier proteins
How do differences in WP/conc gradients affect the rate of movement?
larger gradient = faster rate of movement across the membrane
Why is membrane called fluid mosaic?
mixture and movement of lots of substances it’s made up of e.g phospholipids, glycoproteins, glycolipids, cholesterol, carbohydrates
Describe the purpose of cholesterol
- keeps membrane rigid
- prevents leakage of water and dissolved ions from cell
Describe the purpose of glycolipids
- act as cell surface receptors
- allow cells to adhere to each other causing tissue formation
Describe the purpose of glycoproteins
- cell recognition
- tissue formation
Define endocytosis
large particles enclosed in vesicles transported into a cell
Define exocytosis
large particles in vesicles fuse with cell-surface membrane and are released from cell
