10. If a person expressed mutated genes or lost the enzymes usedfor rearrangement of heavy chain and light chain genes what mighthappen to that person? What cells would be affected? How would theperson be affected as a whole? (2pts)

11. What is the purpose and function of MHC I and MHC IImolecules? (2pts)

12. One of the characteristic features of the MHC receptors isthe large number of different alleles at each gene locus encodingfor the receptor.

a. Where are most of the polymorphic amino acidresidues located in MHC molecules? What is the significance of thislocation? (2pts)

b. What are some of the mechanisms that resultin the MHC polymorphism we see in individuals? (2pts)

13. What is the purpose of class I MHC molecules? What cellsdisplay these molecules? Where do the antigens they display comefrom? (3pts)

14. What is the purpose of class II MHC molecules? What cellsdisplay these molecules? Where do the antigens they display comefrom? (3pts)

15. What kind of proteins are considered class III MHCmolecules? What role in immunity do they play? (2pts)

16. What are professional APCs? Name some examples ofprofessional APCs. (2pts)

17. Give an example of a nonprofessional APC. When can thesecells function in antigen presentation? (2pts)

18. A process called antigen cross-presentation happens indendritic cells only. Explain what cross-presentation is (4pts)

19. Molecules of the CD1 family have been shown to presentnon-peptide antigens. What types of antigens do they present?(2pts)