Transportation Flashcards
(15 cards)
What is a cell membrane
Partially permeable fluid mosaic model consisting of phospholipid bilayer
What does cell membrane contain
Phospholipid bilayer
Intrinsic proteins
Extrinsic proteins
Cholesterol
Glycolipids
Describe bilayer
Phospholipids
Hydrophobic tail faces in
Hydrophilic head faces out
What can simple diffuse through cell membrane
Lipid soluble molecules, water and other small molecules
Not water soluble or larger
Diffusion
Net movement of very small polar or non polar molecules from an area of high and low concentration
Passive process and down conc gradient
Facilitated diffusion
Large or charged molecules use protein channels/carriers to cross membrane
Passive
Down conc gradient
Involves proteins specific to the substance crossing
Osmosis
Net movement of water from and area of higher water conc to an area of lower water conc/potential across a partially permeable membrane
Hypotonic solution
Water moves in
May burst
Isotonic
Stays same
Hypertonic
Water moves out
Shrinks
Fluid mosaic pattern
Molecules moving relatively to each other made up of proteins, glycoprotein’s cholesterol and phospholipids
Factors changing diffusion rate (increase)
Larger SA
Short diffusion pathway
Higher temp
Larger conc gradient
Carrier proteins as limiting factors
Carrier proteins can become limiting factor in diffusion because they become fully saturated in a given period of time
Active transport
Net movement of molecules from an area of low concentration Passive process to high concentration using energy and carrier proteins
Requires ATP
Active transport in glucose absorbtion
1) sodium ions actively transported from ileum epithelium cell to blood by NA/K pump
2) maintains diffusion gradient for sodium to enter cells from the lumen of ileum
3) glucose is higher concentration in the cell so moves by facilitated diffusion into the blood
