Membrane Components Flashcards
Triacylglcerols and free fatty acids
act as a phospholipid precursors and are found in low levels in the membrane
storage lipids involved in human metabolic processes
3 fatty acid chain esterified to a glycerol molecule
Glycerophospholipids
replace one fatty acid with a phosphate molecule, which is often linked to to other hydrophilic groups
used for membrane synthesis
can produce a hydrophilic surface layer on lipoproteins
phospholipids are the primary component of cell membranes - serve not only as structural roles but can also serve as second messengers in signal transduction
Cholesterol
present in large amounts and contributes to membrane fluidity and stability
necessary in the synthesis of all steroids, which are derived from cholesterol
occupies space between adjacent phospholipids and prevents the formation of crystal structures in the membrane, increasing fluidity.
Waxes
present in very small amounts, if at all; they are most prevalent in plants and function in waterproofing and defense.
provide membrane stability
very hydrophobic
composed of a long chain fatty acid and a long chain alcohol
can provide both stability and rigidity within the non polar tail region only.
most serve an extracellular function in protection or waterproofing
Proteins located within the cell membrane act as
transporters, cell adhesion molecules and enzymes
Transmembrane proteins
can have one or more hydrophobic domains and are most likely to function as receptors or channels.
pass completely through the lipid bilayer
ex: transporter, channels and receptors
Embedded proteins
most likely part of a catalytic complex or involved in cellular communication
associated with only the interior of the plasma membrane; partially hydrophobic.
Membrane associated proteins
act as recognition molecules or enzymes
may be found on G proteins in G protein coupled receptors
Carbohydrates can form what kind of coat?
glycoprotein coat and also function in cell recognition
Extracellular ligands can bind to membrane receptors and function as…
channels or enzymes in second messenger pathways
Gap junctions
allow for the rapid exchange of ions and other small molecules between adjacent cells
doesn’t transfer proteins
Tight junctions
prevent solutes from leaking into the space between cells via paracellular route, but do not provide intercellular transport
Found in epithelial cells
can limit permeability enough to create a transepithelial voltage difference based on differing concentrations of ions on either side of the epithelium.
To be effective, tight junctions muse form a continuous band around the cell, otherwise fluid could leak through spaces between tight junction.
Desmosomes and hemidesomsomes
anchor layers of epithelial tissue
Unsaturated fatty acids
“healthier”
tend to have one or more double bonds and exist in liquid form at room temperature
Saturated fatty acids
“less healthy”
found in processed food
main components of animal fats and tend to exist as solids at room temperature
decrease the overall membrane fluidity
