Term 1- Lec 5- Cell Membranes Flashcards
Components of Glycerophospholipids
2 FAs—Glycerol—Phosphate—X ; X can be choline, serine, etc. (Phosphatidylcholine, Phosphatidylserine)
Components of Sphingolipids
1 FA—Sphingosine (contains one long chain)—Phosphate—X. Ex: Sphingomyelin, Glycosphingolipids.
What is the most abundant lipid in membranes?
Glycerophospholipids (The typical phospholid shown in diagrams)
What is characteristic of glycophospholipids and why is it crucial to membrane properties/structure?
ONE of the FA tails has one or more CIS- bonds that cause a kink in the structure. This allows them to remain fluid for a wider range of temperatures.
What is the backbone of a glycophospholipid?
Glycerol
What is the backbone of a sphingolipid?
Sphingosine
Ceramide is made up of what two structures?
Sphingosine and a FA chain
Adding a sugar to ceramide creates what? What are these precursor to?
Glycolipids. They are found most commonly in NERVE TISSUES. They are precursors for Cerebrosides and Gangliosides.
What lipids are important in nerve tissues and prevalent in brain cell membranes?
Cerebrosides
What are the most complex sphingolipids; found primarily in a certain type of cells in the CNS? What type of cell are they primarily in?
Gangliosides. They are found in Ganglion Cells.
What are the components of Cholesterol?
1 FA—steroid ring structure—small polar head.
What effet does cholesterol have on membrane fluidity?
At High T, it prevents the membrane from becoming too fluid. At Low T, it lowers the point at which membranes become gel-like.
What membrane components are most common in the outer leaflet of the cell membrane?
Sphingomyelin, Glycolipid, Phosphatidylcholine, and Cholesterol
What membrane components are most common in the inner leaflet of the cell membrane?
Phosphatidylserine, Phosphatidylinositol, and Phosphatidylethanolamine
What are the components of Sphingomyelin?
(1 FA—Sphingosine)=Ceramide—Phosphate—Choline
What are the common components of a Lipid Raft?
Sphingomyelin, Glycolipids, Cholesterol, and GPI-anchored proteins
What processes are lipid rafts necessart for?
Endocytosis and Receptor-Mediated Signaling
5 types of movement exhibited by glycerolphospholipids and sphingolipids?
Lateral Diffusion, Rotation, Swing (tails swinging), Flexion (compression of tails), Transverse (flip-flop)
What determines much of the functions of a membrane?
Protein portions. i.e. Myelin membrane is ~25% protein and Inner Mitochondrial membrane is ~75%
What membrane component anchors most proteins to the outer leaflet?
GPI—Glycophosphatidylinositol.
What is good about proteins being connect to GPI on the outer leaflet of a membrane?
Proteins in the membrane can quickly cleave the GPI-Protein bond to release the protein into the Extracellular space.
3 movements that membrane proteins can exhibit
Rotational, Lateral movement, Conformational changes (transport proteins)
Carbohydrates can only be found on which surface of the cell membrane?
Extracellular surface (Noncytoplasmic)
Where and What is the Glycocalyx?
Located extracellularly. It is a carbohydrate-rich zone just off of the cell membrane.
What enzymatic reaction is crucial to the formation of the glycocalyx?
Glycosylation
What are the 3 main functions of the Glycocalyx?
Cell recognition, Cell signaling, and Water Absorption
The glycocalyx of RBC’s determines
ABO blood types
The 3 functions of glycocalyx in the intestines
- Provides an additional surface that aids in absorption
- Contains enzymes that aid in digesting macromolecules
- Protects enterocytes from friction and digestive enzymes
Lipid associated diseases (2)
Multiple Sclerosis and Niemann-Pick Disease
Membrane Protein associated diseases (3)
Cystic Fibrosis, Duchenne, Muscular Dystrophy
Glycosylation-related diseases (1)
Congenital disorders of Glycosylation
Multiple Sclerosis
An autoimmune response that leads to the destruction of myelin producing cells. Demyelinated nerve cells struggle to transmit nerve signals.
Niemann-Pick Disease: Types A and B
Sphingomyelinase deficiency leads to accumulation of sphingomyelin in the spleen, liver, lungs, bone marrow, and brain causing irreversible brain damage. Type A: Infants. Type B: Pre-teen.
Cystic Fibrosis
Defective Cl- transporters in epithelial cells result in abnormally thick, sticky mucus that obstructs respiratory pathways.
Congenital Disorders of Glycosylation (CDG)
Defects in the glycosylation pathway leads to abnormal glycocalyces (glycocalyx-es).
