Biology chapter 5

Polar_____are typically found attached to the outside of a membrane. A)phospholipids B)Nucleci acids C) Carbohydrates D) proteins

C) Carbohydrates

Mammals like caribou that live in the arctic often have different lipids in the cells of their legs compared to the cells of their internal organs. Their legs get colder than their internal organs, which stay warmer. Indicate true or false which of the following adaptations you would expect to find in the lipids found in the cells of the legs of a caribou? A. The lipids would be more saturated. B. The fatty acyl tails of the phospholipids would be shorter. C. The membranes would contain more cholesterol

A. The lipids would be more saturated. FALSE B. The fatty acyl tails of the phospholipids would be shorter. TRUE C. The membranes would contain more cholesterol. TRUE

Health Implications of Facilitated Diffusion GLUT1 is a glucose transporter that is responsible for the facilitated diffusion of glucose across the blood-brain barrier. GLUT1 deficiency syndrome is a rare genetic disorder where mutations in the gene encoding GLUT1 reduce or eliminate the function of the GLUT1 protein. Affected individuals suffer from seizures along with a number of potential neurological problems. What is the link between GLUT1 dysfunction and these neurological complications? A)diffusion of glucose from the brain to the blood B)sporadic and uncontrolled diffusion of glucose from the blood to the brain C)excessive and constant diffusion of glucose from the blood to the brain D)insufficient diffusion of glucose from the blood to the brain

B) insufficient diffusion of glucose from the blood to the brain

Larger ____________ make up half of the mass of a membrane. A)phospholipids B)Nucleci acids C) Carbohydrates D) proteins

D) proteins

Small amphipathic___________ are the most abundant molecules in a membrane. A)phospholipids B)Nucleci acids C) Carbohydrates D) proteins

A)phospholipids

Membrane Permeability and Facilitated Diffusion Which of the following molecules are most likely to pass through the membrane by facilitated diffusion? A)urea and sucrose. B)H2O and O2. C)CO2 and O2. D)CO2 and H2O.

A)urea and sucrose.

Which of the following is the most direct source of energy for cotransport? A)the movement of one of the transported substances up its concentration gradient B)the movement of one of the transported substances down its concentration gradient C)ATP hydrolysis D)ATP formation E)cotransport requires no energy

B)the movement of one of the transported substances down its concentration gradient

Receptor Mediated Endocytosis Lipoproteins like LDL and HDL transport lipids and proteins through the blood stream. Receptors on cells can bind to the lipoproteins and remove them from the blood, using the lipids for energy and to produce membranes. Which of the following mechanisms would be used to move a lipoprotein into a cell? A)Active transport B)Facilitated diffusion C)Receptor-mediated endocytosis D)Endocytosis E)Exocytosis

C) Receptor-mediated endocytosis

Aquaporin allows water molecules to move very rapidly across a plasma membrane. What would be the best definition of this process? A)Facilitated diffusion using a transporter B)Active transport using a transporter C)Facilitated diffusion using a channel D)Active transport using a channel

C)Facilitated diffusion using a channel

Secondary Active Transport of Sucrose Sugars can be transported into cells against their concentration gradient because of A)osmosis. B)simple diffusion. C)facilitated diffusion. D)antiport with Na+. E)symport with Na+.

E)symport with Na+.

Compare Facilitated and Simple Diffusion Unlike simple diffusion, facilitated diffusion requires energy expenditure by the cell. True False

FALSE

Administration of digoxin is not the only way to treat atrial fibrillation. From the list below, select all other plausible strategies to increase intracellular calcium concentrations. A)Administer a different inhibitor of the Na+/Ca2+ antiporter B)Administer an inhibitor of the Ca2+-ATPase pump, which removes Ca2+ from the cytosol C)Administer calcium chelators to reduce the extracellular Ca2+ concentration D)Administer calcium chloride to raise the extracellular Ca2+ concentration

A)Administer a different inhibitor of the Na+/Ca2+ antiporter B)Administer an inhibitor of the Ca2+-ATPase pump, which removes Ca2+ from the cytosol D)Administer calcium chloride to raise the extracellular Ca2+ concentration

N-linked protein glycosylation Which of the following is true of N-linked protein glycosylation? A)The carbohydrates are first attached to the lipid dolichol. B)It occurs entirely in the Golgi apparatus. C)It occurs primarily on proteins that are not secreted out of the cell. D)The carbohydrates are attached directly to the protein.

A)The carbohydrates are first attached to the lipid dolicho

Analyze a Defective Na+/K+ ATPase A defective Na+/K+ ATPase pump is isolated from a plasma membrane and studied. Careful measurements in the laboratory determine that the pump is able to hydrolyze ATP and transports 3 Na+ ions across the plasma membrane. The pump is also able to bind 2 K+ ions with high affinity. However, the pump is unable to shuttle K+ ions across the plasma membrane. Based on these observations, what is the most likely cause of the defect in this pump? A)The defective pump is unable to release phosphate B)The defective pump is locked into a rigid conformation and is unable to undergo conformational changes C)The defective pump is unable to release Na+ ions D)The defective pump is unable to bind K+ ions E)The defective pump is unable to bind ATP

A)The defective pump is unable to release phosphate

Describe the Na+/K+ ATPase Pump A)The sodium-potassium pump functions to pump sodium ions out of the cell and potassium ions into the cell. B)sodium ions into the cell and potassium ions out of the cell. C)sodium and potassium ions into the cell. D)sodium and potassium ions out of the cell. E)sodium and potassium ions in both directions across the cell membrane.

A)The sodium-potassium pump functions to pump sodium ions out of the cell and potassium ions into the cell.

Energy Source for Na+/K+ Pump What is the source of energy used to power the sodium-potassium pump? A)hydrolysis of ATP B)formation of ATP C)binding of ATP D)release of phosphate E)diffusion of Na+ down its gradient

A)hydrolysis of ATP

The Energetics of Coupled Transport Sucrose concentration is higher in the cytoplasm than in the extracellular environment. Na+ concentration is higher in the extracellular environment than in the cytoplasm. Animal cells can take up sucrose against its concentration gradient using a Na+/sucrose symporter. Indicate if the following statements are true or false. A. In the Na+/sucrose symporter, Na+ is also moving against its concentration gradient. B. For the symporter to work, the cell must first establish a Na+ concentration gradient. C. A symporter works by making the phospholipid bilayer more permeable to ions and sucrose. D. Moving sucrose against its concentration gradient is a form of active transport. E. A Na+/sucrose antiporter would be capable of moving sucrose into the cell while moving Na+ out of the cell. F. Since the Na+/sucrose symporter exchanges a single sucrose for a single Na+, it can also be considered a uniporter

A. In the Na+/sucrose symporter, Na+ is also moving against its concentration gradient.FALSE B. For the symporter to work, the cell must first establish a Na+ concentration gradient. TRUE C. A symporter works by making the phospholipid bilayer more permeable to ions and sucrose. FALSE D. Moving sucrose against its concentration gradient is a form of active transport. TRUE E. A Na+/sucrose antiporter would be capable of moving sucrose into the cell while moving Na+ out of the cell. FALSE F. Since the Na+/sucrose symporter exchanges a single sucrose for a single Na+, it can also be considered a uniporter. FALSE

Membrane proteins Indicate if the following statements about membrane proteins are true or false. A. They can aid in the transportation of molecules across membranes. B. They are used in DNA replication. C. They can act as cell surface receptors. D. They are totally water soluble. E. They can be enzymes

A. They can aid in the transportation of molecules across membranes. TRUE B. They are used in DNA replication. FALSE C. They can act as cell surface receptors. TRUE D. They are totally water soluble. fFALSE E. They can be enzymes. TRUE

Digoxin is an inhibitor of Na+/K+ ATPase that is used to treat irregular heartbeats (medical term: atrial fibrillation). Digoxin slows the heartbeat by raising intracellular calcium levels. What is the most reasonable explanation for how digoxin can raise intracellular calcium concentrations through inhibiting Na+/K+ ATPase? A)Na+/K+ ATPase acts to shuttle Ca2+ out of the cell. Digoxin inhibits Na+/K+ ATPase, preventing it from shuttling Ca2+ out of the cell. As a result, intracellular Ca2+ levels increase. B)Inhibiting Na+/K+ ATPase results in a lower than normal intracellular Na+ concentration. This reduces the effectiveness of the Na+/Ca2+ antiporter. As a result, intracellular Ca2+ levels increase. C)Inhibiting Na+/K+ ATPase results in a higher than normal intracellular Na+ concentration. This reduces the effectiveness of the Na+/Ca2+ antiporter. As a result, intracellular Ca2+ levels increase. D)Inhibiting Na+/K+ ATPase results in a lower than normal extracellular K+ concentration. This increases the effectiveness of a K+/Ca2+ symporter that drives the influx of both K+ and Ca2+. As a result, intracellular Ca2+ levels increase.

B)Inhibiting Na+/K+ ATPase results in a lower than normal intracellular Na+ concentration. This reduces the effectiveness of the Na+/Ca2+ antiporter. As a result, intracellular Ca2+ levels increase.

Compensating for Disfunction in Facilitated Diffusion GLUT1 deficiency syndrome is a rare genetic disorder where mutations in the gene encoding GLUT1 reduce or eliminate the function of the GLUT1 protein. Affected individuals suffer from seizures along with a number of potential neurological problems. What would be the most effective therapy to treat patients suffering from this disorder? A)Treat with drugs that will elevate ATP levels in the blood-brain barrier and promote the active transport of glucose by GLUT1 B)Switch to a diet containing carbohydrates other than glucose to circumvent the deficient transport C)Switch to a high glucose diet to overcome the deficient transport D)Regularly inject GLUT1 into the patient's blood to serve as a replacement for the deficient transporter

B)Switch to a diet containing carbohydrates other than glucose to circumvent the deficient transport

Requirements of Facilitated Diffusion Facilitated diffusion requires A)enzymes. B)carrier proteins. C)lipid carriers. D)carbohydrate carriers. E)lipid or carbohydrate carriers.

B)carrier proteins

Calculated the Charge Differential after Multiple Pump Cycles A single Na+/K+ ATPase pump is present in the plasma membrane of an artificial cell with an initial cellular environment of 500 molecules of Na+ and 1000 molecules of ATP inside the cell, 500 molecules of K+ outside the cell, and a net charge differential across the plasma membrane of 0. Assuming the only changes in the cellular environment are a result of the pump's actions, what would be the number of Na+, K+ and ATP molecules inside the cell after 10 cycles of the pump and what would be the net charge differential (inside - outside) across the plasma membrane? A)30 Na+; 20 K+; 900 ATP and -10 charge differential (inside - outside) B)30 Na+; 480 K+; 10 ATP and +20 charge differential (inside - outside) C)470 Na+; 20 K+; 990 ATP and -20 charge differential (inside - outside) D)300 Na+; 200 K+; 100 ATP and -100 charge differential (inside - outside) E)470 Na+; 480 K+; 10 ATP and +100 charge differential (inside - outside)

C) 470 Na+; 20 K+; 990 ATP and -20 charge differential (inside - outside)

Evaluate the Relative Impact of Na+/K+ ATPase Disfunction Which of the following dysfunctions in the Na+/K+ ATPase will have the most dramatic effect on the establishment of a concentration gradient? A)A reduction in the ability of ATP to bind to the pump B)A decrease in the Na+ binding affinity for the phosphate-bound form C)A reduction in the rate of ATP hydrolysis D)An increase in the K+ binding affinity in the phosphate-bound form

C) A reduction in the rate of ATP hydrolysis

Pumps The plasma membrane Ca2+-ATPase is a pump that functions in the primary active transport of Ca2+ out of the cell. What features do you expect of this pump and the cellular environment? Choose all that apply. A)It transports Na+ and K+ ions B)It is an antiporter C)The extracellular Ca2+ concentration is higher than the intracellular Ca2+ concentration D)It hydrolyzes ATP E)It is capable of undergoing a conformational change F)The affinity for Ca2+ is low when the enzyme is bound to phosphate G)It transports Ca2+ down its concentration gradient

C)The extracellular Ca2+ concentration is higher than the intracellular Ca2+ concentration D)It hydrolyzes ATP E)It is capable of undergoing a conformational change F)The affinity for Ca2+ is low when the enzyme is bound to phosphate

Fluid mosaic model of membrane structure Which of the following is true of the fluid mosaic model of membrane structure? A)Membranes behave more like a solid than a liquid. B)Lipids can flip from one leaflet to another as easily as they can move laterally in a membrane. C)Proteins can easily move across membranes. D)Proteins can easily move laterally through membranes.

D)Proteins can easily move laterally through membranes.

A toxin that disrupted membrane antiport would prevent A)simultaneous movement of an amino acid and protons into the cell B)simultaneous movement of an amino acid and protons out of the cell C)coupling of the inward movement of water with the outward movement of protons D)coupling the outward movement of Ca2+ with the inward movement of Na+

D)coupling the outward movement of Ca2+ with the inward movement of Na+

The hormone insulin is a protein produced in the pancreas and then secreted into the blood stream after a meal to increase glucose uptake by tissues. Which of the following mechanisms would be used to secrete insulin from the pancreas? A)Active transport B)Facilitated diffusion C)Diffusion D)Endocytosis E)Exocytosis

E)Exocytosis