The pKa of an acid depends partly on its environment. Predict the effect of each of the following environmental changes on the pKa of a glutamic acid side chain. (a) A lysine side chain is brought into proximity. (b) The terminal carboxyl group of the protein is brought into close proximity.

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

The scheme below is from a series of reactions that are part of a synthesis of vitamin a. answer the following questions with reference to this scheme. (i) what is "reagent a"? (ii) draw a step-by-step mechanism which explains the formation of compound c from compound b (iii) which reagents would you use to form compound e from compounds c and d (reagents b and c)? for each reagent suggested above in (ii) explain the role of the reagent in the reaction to (iv) form compound e. you may wish to do this by drawing a mechanism. 1. addition of reagent a но reagent a 2. н, о" thо oh нон-с compound a. compound b. compound c .ch-оh 1. reagent b "сно 2. reagent c сh oh compound e. compound d.

Which is true of a liquid? it has a definite volume but not a definite mass. it has a definite mass but not a definite volume. it has a definite volume but not a definite shape. it has a definite shape but not a definite volume.