30 Questions
Which substituent is added to phosphatidic acid to form phosphatidylcholine?
Choline
What is the major function of phosphatidylinositol in the cell?
To act as a precursor for second messengers in cell signaling
What is the major constituent of the lung surfactant that prevents the adherence of inner lung surfaces?
Phosphatidylcholine
Which phospholipid is involved in the LCAT (lecithin cholesterol acyl transferase) activity of HDL?
Phosphatidylcholine
Which phospholipid is considered the most abundant in the cell membrane?
Phosphatidylcholine
What is the main function of cardiolipin in the body?
No specific function is mentioned in the text
Which component of the signal transduction system is detected in caveolae?
Insulin receptor
What is the primary function of tight junctions in epithelial cells?
To prevent the diffusion of solute macromolecules
Which type of transport system allows small molecules to pass directly from the membrane?
Simple passive diffusion
Which cells contain the SGLT system?
Epithelial cells of enterocytes, Choroid plexus, and Renal tubules
What is the composition of a gap junction?
Six connexins forming a connexin hemichannel
Which type of transport system requires a specific transporter (pump)?
Active transport
What is the role of aquaporins?
To facilitate the movement of water across the cell membrane
What are the two types of cotransport systems mentioned in the text?
Uniport and cotransport
What is the consequence of insensitivity of AQP2 to ADH in the proximal tubule of the kidneys?
Polyuria (greater urine output) and more dilute urine, a pathology called nephrogenic diabetes insipidus (NDI)
What is the difference between diffusion and active transport?
Diffusion moves molecules down their concentration gradient, while active transport moves molecules against their concentration gradient
What is the primary function of the Na+-K+-ATPase enzyme?
To maintain a high intracellular Na+ concentration and a low intracellular K+ concentration
What percentage of the total energy expenditure in a cell is consumed by the maintenance of electrochemical gradients?
30%
What type of molecules are central players in cell-cell recognition and adhesion, cell migration, blood clotting, immune response, and wound healing?
Carbohydrates
Which type of molecule is covalently joined to a protein or a lipid to form a glycoconjugate?
Carbohydrates
Which glycoprotein found in human erythrocytes increases the flip-flop frequency of membrane phospholipids?
Glycophorin
What are proteins, enzymes, pumps, transporters, channels, structural components, antigens, and receptors examples of in membranes?
Carbohydrates
Which type of membrane proteins are loosely bound to the membrane and can move through it?
Peripheral proteins
Which proteins are classified into two types as integral and peripheral in the context of membrane proteins?
Enzymatic proteins
What is the primary role of the Na+-K+ ATPase in the Na+glucose symporter system?
To generate a steep Na+ gradient for the symporter to function
What is the term used for the binding constant of a solute to a transporter protein?
Km
What is the process by which a cell releases macromolecules, such as hormones?
Exocytosis
Which of the following is a type of endocytosis?
Phagocytosis
Which of the following is NOT a similarity between transporter-mediated facilitated diffusion and active transport?
Both require energy input from ATP hydrolysis
Which of the following statements is NOT true about endocytosis and exocytosis?
They are independent processes that do not involve each other
Test your knowledge on how the O— shown shaded in phosphatidic acid is substituted to form various phospholipids like Phosphatidylcholine, Phosphatidylethanolamine, Phosphatidylserine, Phosphatidylinositol, and Cardiolipin. Explore the structures and derivatives of these important components of cell membranes.
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