The sequence of amino acids within a polypeptide chain represents the key factor in which level(s) of protein structure?

What would be the net charge on the amino acid cysteine at pH 7.4?  

SOURCE C

SOURCE D

Which of the following amino acids has a nucleophilic side chain?

COP I vesicles are involved in:  

SOURCE G There exist inside the League two ideas about how best to preserve peace. There is the idea that when a state announces a foreign policy based on aggression and invading other countries’ frontiers, the League has the duty of declaring that it will fight such a policy with every means at its disposal. There  is,  however,  another  idea  that  the  aggressor  should  be  treated  with  consideration  and  that  negotiations should be carried out with the assurance that no collective action will be carried out.  Unfortunately, this is the policy that has so far been followed and it has as its consequences three wars and threatens to bring us a fourth. Maxim Litvinov speaking at the League of Nations Assembly, September 1938. Litvinov was in charge of Soviet foreign policy.

In the manufacture of a drug substance by cooling crystallisation at 250°C there are 260 g L-1 solute in solution. The saturated solubility of the solute at 60°C is 20 g L-1. What is the amount of the solute that can be crystallised in 1 L by cooling down to 60°C?  

Now answer all the following questions. You may use any of the sources to help you answer the questions, in addition to those sources which you are told to use. In answering the questions you should use your knowledge of the topic to help you interpret and evaluate the sources. 1 Study Sources A and B. How far do these two sources agree? Explain your answer using details of the sources. {7}   2 Study Sources C and D. How similar are these two cartoons? Explain your answer using details of the sources and your knowledge. {8}   3 Study Source E. What is the cartoonist’s message?  Explain your answer  using  details  of  the  source  and  your knowledge. {8}   4 Study Source F. Are you surprised by  this  source?  Explain  your  answer  using  details  of  the  source  and  your  knowledge. {8}   5 Study Sources G and H. How far does Source G prove that Source H is wrong? Explain your answer using details of the sources and your knowledge {7}   6 Study all the sources. How far do these sources provide convincing evidence that the League of Nations was a failure?  Use the sources to explain your answer. {12}

SOURCE F I  would  like  to  speak  about  the  League  and  the  policy  of  collective  security  which  we  have  whole-heartedly supported with such disappointing results. The dispute between Italy and Abyssinia was a perfect opportunity for the exercise of that policy. It has been tried based on sanctions and it has failed to prevent war, failed to save the victim from the aggressor. The other day the President of the League of Nations said that if we were to pursue the policy of sanctions it was still possible to preserve the independence of Abyssinia. That seems to me to be madness. We must admit we have tried to impose upon the League a task which was beyond its powers to fulfill. It is time to limit the functions of the League so that they match with its real powers.  But if the League is to be limited in that way it must be admitted that it could no longer be relied upon to secure the peace of the world. From a speech by Neville Chamberlain, a leading member of the British  government, June 1936.