29 Questions
What is the principal sialic acid found in human tissues?
Neuraminic acid
Which glycolipid is present in high amounts in myelin?
Sulfatide
What type of molecules does ganglioside contain in addition to glucosylceramide?
Sialic acid
Which sterol is the most common in the membranes of an animal cell?
Cholesterol
Where does the majority of cholesterol reside within the cell?
Plasma membrane
How does cholesterol modify the fluidity of membranes?
By acting as a buffer
What is the main function of membranes in a cell?
To localize enzymes
Where are choline-containing phospholipids mainly located in the cell membrane?
Outer leaflet
What is the consequence of inhibiting Na+-K+ ATPase by digoxins or digitals?
Decrease in water balance
What do specific deficiencies or alterations of membrane components lead to?
Variety of diseases
How are membranes described in terms of their structure and surfaces?
Protein-studded
What term describes membranes as having both hydrophobic and hydrophilic compartments?
Amphipathic
Which membrane structure has the highest protein content due to the presence of the electron transport chain and carrier proteins?
Mitochondrial inner membrane
What are lipid rafts enriched in, making them specialized areas in the plasma membrane?
Cholesterol, sphingolipids, and certain proteins
Which specialized plasma membrane structure is involved in signal transduction and interact with the actin cytoskeleton?
Lipid Rafts
What is the function of caveolae in the plasma membrane?
They may derive from lipid rafts
Which membrane structure is known for being an electrical insulator on many nerve fibers?
Myelin
What makes the mitochondrial inner membrane the most selectively permeable membrane known?
Presence of carrier proteins
Which type of molecules are triacylglycerols (TAGs) and cholesterol-esters?
Hydrophobic
Why are pure hydrophobic molecules like TAGs and cholesterol-esters not present in membranes?
Their hydrophobic nature prevents interactions with the membrane components
What kind of structure forms a fluid mosaic model in cell membranes?
Amphipathic
What property makes the lipid bilayer impermeable to most water-soluble molecules?
Hydrophobic core
Which gases readily diffuse through the hydrophobic regions of the membrane?
Oxygen and carbon dioxide
Which type of molecules are most likely to have a high permeability coefficient in a lipid bilayer?
Small nonpolar molecules
What is the effect of the Na+-K+-ATPase pump on the cell interior?
Causes an electrogenic effect, making the cell interior more negative
Which statement about Na+-K+-ATPase inhibitors ouabain and digitalis is true?
They inhibit the Na+-K+-ATPase pump
How does glucose enter the cell in the Na+-glucose symport?
Glucose is dragged into the cell along with Na+
What happens to glucose transport when the extracellular Na+ concentration is low?
It stops as Na+ is needed to 'drag' glucose into the cell
What role does the Na+-K+-ATPase pump play in relation to secondary active transporters?
It can be coupled to them to support their transport functions
Test your knowledge on glycolipids with a focus on glycosphingolipids, sulfatides, and gangliosides. Learn about the structure, components, and functions of these important lipids found in cell membranes.
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