Q Search 262018 QUESTION 2 points Save Anawer Which of the folllowing types of s
ID: 216367 • Letter: Q
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Q Search 262018 QUESTION 2 points Save Anawer Which of the folllowing types of signaling molecules would be able to bind to an nl intracellular receptor rather than a cell-surface receptor? O A an amino acld O B- a peptide O C- a steroid O D. a protein QUESTION 10 2 points Save Answer Which of the following factors would tend to increase membrane fluidity in animal cells? OA a greater proportion of saturated phospholipids B. a greater proportion of unsaturated phospholipids O C a smaller amount of cholesterol in the membrane at higher temperatures OD a larger amount of cholesterol in the membrane at lower temperatures OE B, C, and D would all tend to increase membrane fluidity. QUESTION 11 2 pointsSave Answer Mutations in the CFTR protein cause cystic fibrosis. CFTR is a chioride ion channel that opens when ATP binds to it. In its open state, chloride ions flow through CFTR down their concentration gradient. Which of the following is NOT true about CFTR? A CFTR engages in active transport of chioride ions. B. CFTR is an example of a ligand-gated channel. ° C. Dissociation of ATP from CFTR causes a conformational change. D. CFTR is amphipathic, with hydrophobic groups facing towards the phospholipid tails of the membrane and hydrophilic groups forming the channel cusExplanation / Answer
9) STEROID would be more likely to bind to an intracellular receptor than a cell surface receptor. It is because, the steroids are hydrophobic and can pass through the plasma membrane that is why its more likely to bIND to an intracellular receptor.
10) B, C, D all tend to increase membrane fluidity. Membrane fludity is mainly controlled by three factors, temperature, cholestrol and saturated and unsaturated fatty acids. Here, in the question about the cholestrol,at higher temperatures, the phospholipids of the membrane move a bit far apart, which means fluidity increases. But when we add cholestrol, it adds up at random places, and pull the membrane molecules closer, which means the space for other molecules decrease, i.e the fluidity decrease, so a smaller amount of cholestrol required at higher temperature. While its exact the opposite at lower temperatures, as then the membrane phospholipds cluster together very close, by which fluidity decrease but the cholestrol molecules somehow increase the distance between the fluids by binding to the phospholipds, hence increasing the fluidity. The cholestrol at low temperature actually inserts itself in the membrane, which means more cholestrol at low temperatures. In case of saturated fatty acids, they stack together neatly with the membrane phospholipds, while the unsaturated ones dont do that properly. Due to the neat and closed stacking of staurated fatty acids they will cluster together decreasing the distance between the membrane phospholipds hence decreasing the fluidity. While the unsaturated fatty acids, will have an unsaturated bend by which the distance increases, increasing the mebrane fluidity.
11) CFTR is not amphipathic, as it is a typical ABC protien, that means it has four domains, two cytoplasmic neucleotide binding domains and two transmembrane domains, witn head-tail arrangement of neucleotide binding proteins . The CFTR is an example of ligand gated channel, which is engaged in active transport of chloride ions. The dissociation of ATP causes conformational changes but does not aid at all in opening and closing of gates.
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