Bio Ch. 5 Flashcards
Phospholipids arranged in a
Bilayer
Fluid mosaic model:
mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond
Cellular membranes have four components
- Phospholipid bilayer
- Transmembrane proteins
Flexible matrix, barrier to permeability. - Interior protein network
- Cell surface markers
Studying the cell membrane
The transmission electron microscope (TEM) and scanning electron microscope (SEM)
Phospholipids
Structure consists of:
-Glycerol
- Two fatty acids attached to the glycerol.
1. Nonpolar
2. hydrophobic (“water-fearing”). - - - - -Phosphate group attached to the glycerol.
1. Polar
2. hydrophilic (“water-loving”).
hydrophilic
(“water-loving”)
Glycerol
a 3-carbon polyalcohol.
(- Two fatty acids attached to the glycerol)
Phospholipids Spontaneously forms a
Bilayer
Phospholipid bilayer structure
-Hydrocarbon tails are on the inside.
-Polar head groups are on the outside (toward water).
Phospholipid bilayer
-Bilayers are fluid
-Hydrogen bonding of water to itself and to polar heads, holds the layers together
-Individual phospholipids and unanchored proteins can move through the membrane
Membrane proteins
- Transporters
- Enzymes
- Cell-surface receptors
- Cell-surface identity markers
- Cell-to-cell adhesion proteins
- Attachments to the cytoskeleton
Structure relates to
function
- Have common structural features related to their role as membrane proteins
Peripheral proteins
Anchoring molecules attach membrane protein to surface.
Pores
- Extensive nonpolar regions within a transmembrane protein can create a pore through the membrane
- Interior is polar and allows water and small polar molecules to pass through the membrane.
Passive transport is
movement of molecules through the membrane in which
Passive transport
- No energy is required
- Molecules move in response to a concentration gradient.
