Biology-Test 2 Flashcards
Phospholipids
A class of lipids that are major components of a cell membrane.They can form lipid bilayers.
Selective Permeability- & effect on polarity
means cell membrane is selective on what comes in and what comes out of the cell. thus polarity has effect on what comes in easily and what comes out.
Properties of Phospholipids
- top is polar, made up of Choline, -charged phosphate and glycerol.
- Bottom is Hydrophobic, made up of two fatty acid tails (hydrocarbon tails)
small, hydrophobic molecules like fatty acids pass through cell membrane easily or hard.
easily pass through a membrane’s lipid bilayer. Thus small and negatively charged usually go through easily. (positively charged substances don’t)
Membranes are?
a fluid mosaic of phospholipids and proteins
how do proteins remain stable in phospholipid bilayer
it’s hydrophobic on the inside and hydrophilic on the outisde.
protein functions
Transport Enzymatic activity signal transduction intercellular joining cell-cell recognition attachment to the cytoskeleton and extracellular matrix (ECM)
diffusion
The process where molecules move from an area of high concentration to an area of low concentration.
why does diffusion occur
molecules bounce of each other when in high concentration, thus tend to go to a lower concentration
passive diffusion
diffusion across a cell membrane that does not require energy.
Rate of diffusion is affected by?
Temperature, Size of Molecules, and steepness of concentration gradient.
Osmosis
Diffusion of water across a membrane.
isotonic
Concentration is the same on both sides.
hypotonic
Refers to a low concentration area, a cell in a Hyoptonic solution indicates a higher concentration of solute inside the cell.
Hypertonic
Refers to a High concentration area, a cell in a Hypertonic solution indicates a higher concentration solute outside the cell.
