Structure Of The Cell Flashcards
Factors that affect membrane fluidity
Number of carbons in tails- longer hydrocarbon chains are more packed together reducing fluidity
Unsaturated or saturated fatty acids: double bonds can produce bends that push away neighbouring lipids increasing fluidity
Temperature: high temps increase fluidity
Cholesterol: cholesterol decreases fluidity by packing to neighbouring lipids
Structure of cell membrane
16-18 carbons in fatty acid chain
Hydrophobic tails and hydrophilic heads
5 to 10 nm in thickness
Function of cell membrane
Disposal of metabolic wastes
Prevent toxic substances getting in
Allows entry or important components
Passive diffusion
No energy used
High concentration to low concentration
Lipid soluble molecules, gases, water and uncharged polar molecules get through
Facilitated diffusion
Small molecules and hydrophilic molecules get through
No energy used
High to low concentration
Proteins are used to transport hydrophilic molecules
Active transport
Requires atp
Goes against concentration gradient
Primary: direct expenditure of atp
Secondary: indirect expenditure of atp
Osmosis
Water goes through
No energy used
Water diffuses from less concentrated to more concentrated
Net movement of water to balance out concentrations
Isotonic
Extra cellular fluid concentration with the same osmolarity as its interior
No net movement of water
Shape is maintained
Hypotonic
Outside has lower solute concentration than inside
Net movement of water to the interior of the cell
Leads to bursting
Hypertonic
Higher solute concentration outside the cell than inside
Water is leaving
Cell shrinking
Aquaporins
Exclusively permeable to water
Allow rapid transport of water through protein channels with a hydrophilic core
Carbohydrates
Important structural components
Sources of stored energy
Lipids
Primary component of cell membranes
Lower permeability
Fewer unsaturated fatty acids
More cholesterol
High permeability
More unsaturated fatty acids
Less cholesterol
