Water is critical for life and is considered the universal solvent because of its unique properties. However, when temperatures drop below the freezing point of water, ice crystals form and can be lethal to cells. Cold-blooded organisms that live in cold climates have evolved mechanisms to cope with freezing temperatures, one of which is the synthesis of antifreeze proteins that block ice crystal growth. The larval antifreeze protein contains multiple stretches of 12 amino acids, repeating the sequence threonine-cysteine-threonine. The placement of the threonines in the repeating amino acid sequence positions hydroxyl groups at precisely the spacing needed to maximize hydrogen bond formation with the water at the leading edge of the ice crystal, and thereby blocks further growth of the crystal lattice.
Part 1 (1 point) See Hint If all the threonines of an antifreeze protein were changed to valines, what would happen to the protein's ability to bind and form complexes with water? O A. The protein would bind water more tightly. O B. The protein would have increased affinity for the phosphate backbone of DNA. O C. The protein would demonstrate no change in water binding. D. The protein would not bind water and would lose antifreeze properties. Part 2 (1 point) Given the Second Law of Thermodynamics, how can reactions that create order (which are entropically unfavorable) occur? Choose one or more: A. Energy is absorbed from the surroundings. B. The unfavorable reaction is coupled to a favorable one. C. It is not possible. D. A favorable enthalpy change overcomes entropic penalty.
