Chapter 6. Lipids, Membranes, And The First Cell Flashcards
Hydrocarbon
- Molecules that contain ONLY carbon & hydrogen
- nonpolar: e- are shared equallY between C-H
- hydrophobic : no partial charge
Lipid
Hydrophobic molecules ( do not dissolve in water)
- fats
- phospholipids
- steroids
Fatty acid
A simple lipid consists of a hydrocarbon chain bonded to a carboxyl ( -COOH) functional group
-most found in their long hydrocarbon “tails”
Saturated fatty acid
Only single bonds between carbons in Hydrocarbon chain
Ex) butter, beeswax
Unsaturated fatty acid
Hydrocarbon contain carbon-carbon double bonds
Ex) safflower oil
Fat
Nonpolar molecules composed of three fatty acids
triglycerides
Glycerol
Three carbon molecule are linked together
Ester linkage
The glycerol and fatty acid molecules become joined.
Steroid
A family of lipid distinguished by 4 ring structure
Ex) cholesterol
Polar hydrophilic + 4 steroid rings + isoprenoid “ tail”
Phospholipids
Consist of a glycerol that linked to a phosphate gate + 2 fatty acids or isoprenoid.
Ex) domain Archaea
- amphipathic
Amphipathic
Compounds that contain both hydrophilic and hydrophobic elements
Lipid bilayer
The foundation of plasma membranes
- hydrophilic heads of lipids face out, toward water
- hydrophobic tails face in, away from water
Permeability
A structure is its tendency to allow a given substance to pass through it
Selective permeability
Only certain substances cross lipid bilayers readily. Size and polarity or charged affect the rate of diffusion across a membrane
Diffusion
Movement of molecules/ions that result from kinetic energy: high concentration to low concentration
