Flashcards in Membranes Deck (40):
Most abundant lipids found in biological membranes
Glycerol backbone, with a phosphate and two fatty acids esterified to backbone
Sphingosine backbone, with LCFA and phosphorylcholine
Sphingosine backbone with carbohydrate (oligosaccharide) residues. Found in outer leaflet
Embedded in lipid bilayer. Steroid nucleus with a hydroxyl group and hydrocarbon side-chain. Lipid Rafts
Which lipids make up the outer sheet of the membrane?
Which lipid is always present in the inner sheet of the membrane except during apoptosis?
Which lipid is a marker for apoptosis?
Phosphatidylserine goes to outer leaflet during apoptosis
Acid Sphingomyelinase deficiency. Results in enlarged liver, spleen and neuro damage, also cherry red spot in the eye
Integral Membrane proteins
embedded in the membrane and stabilized by hydrophobic reactions with lipids
loosely bound to lipids and proteins in membrane through electrostatic interactions
attached via covalent bonds to a lipid
carbohydrate shell located on the outer sheet of the membrane. always covalently bound to either lipids or proteins, never by itself
What are the three functions of Glycocalyx?
Protection, cell adhesion, cell identification
Which type of blood is the universal donor?
Type O because it has no surface antigens
Which type of blood is the universal acceptor
Type AB because it doesn't have any antibodies in the plasma
Explain Rh Factor and hemolytic disease
Erythroblastosis fetalis: when mom is Rh- and baby is Rh+, the mom produces antibodies during pregnancy and the second baby is at high risk if also Rh+
Explain Membrane fluidity
Proteins and lipids rotate and move laterally in membranes, this movement is crucial for function because it allows proteins and lipids to undergo conformational changes.
Factors that influence membrane Fluidity
How does Temp affect fluidity
If temp barely above melting temp(Tm) then optimal fluidity, if below Tm then rigid, if too high then too fluid
How does Lipid Composition affect fluidity?
Saturated FA: lower membrane fluidity
Unsaturated FA: increase fluidity
Cholesterol in rigid membrane
Cholesterol in fluid membrane
Spur Cell Anemia
Elevated levels of Cholesterol result in increased rigidity of membrane leading to RBC's with broken membranes
What kind of molecules can cross membrane via simple diffusion?
Small nonpolar molecules High Concentration to low concentration: O2, N2, Ethanol, Diethylether, Benzene
Small, polar, uncharged molecules:
H2O, CO2, NH3, Urea
high throughput (transport millions of molecules per second)
Ligand-gated ion channels
Ligands bind to transporter allowing for transporter to open and ions to enter.
How do anesthetic affect ion channels
They block the ion channels (pufferfish toxin)
Difference between Primary and Secondary active transport
Primary uses ATP directly, Secondary uses energy stored in concentration gradient
P type ATPases
ATP is hydrolysis gives energy, protein gets phosphorylated. Example: Na+/K+ ATPase and Ca2+ ATPase
ATP is hydrolyzed, but does not phosphorylate the transporter. Active transport goes against the gradient. ATP hydrolized but does not phosphorylate the proteins!
Secondary Active Transport
Moves things against concentration gradient but does not use ATP hydrolysis, Uses coupled reaction of unfavorable flow of one species against its gradient and flow of another with its gradient. Example: SGLT1
Types of Secondary Transporters
Antiporter, symporter, uniporter
Sodium-glucose transporter 1 (SGLT1)
Line small intestine and renal tubes, Unidirectional movement of Na+ with its gradient and Glucose against its gradient.
Na+ - Ca2+ Exchanger (NCX)
Antiporter. Imports 3 Na+ down the gradient and exports 1 Ca2+ against the gradient.
Lumen of intestine
AR disorder. Mutation in CFTR gene which channel that mediates the active transport of Cl- from inside the cells to outside airways. Defective CFTR causes accumulation of Cl- inside the airway leads to thick mucous and leaves airways prone to bacterial infections.
AR disoder caused by defect in transport that uptakes Cystine. Results in Cystine crystal formation.