Immunology                                                                                                        

Practice Exam #2

(1pt each)

Place a T in front of the characteristics unique to T cell epitopes, a B in front of the characteristics of B cell epitopes or an X in front of characteristics common to both T cell and B cell epitopes.

1_____epitopes present on antigens present free in solution

2_____epitopes often present within the interior of a polypeptide

3_____epitopes contain hydrophilic amino acids

4_____epitopes are frequently accessible on the exposed surface of an antigen

5_____antigen processing of the epitope is required for recognition

6_____peptides which must be presented in association with MHC molecules

7_____may be a conformational epitope rather than a sequential epitope

8_____epitopes generally are oligopeptides

(1pt each)                                                                                                                                                   

Fill out the below table by using a (+) if yes or a (-) if no

Multiple Choice Questions (1 pt each)

18.  Which of the following is true of epitopes associated with antigens from an exogenous source:

a)  presented in association with Class I MHC
b)  presented to T helper lymphocytes
c)  presented to T cytotoxic lymphocytes
d)  associate with MHC molecules within the ER

19.  Which of the following mitogens is specific for B cells?

a)  Con A
b)  PHA
c)  LPS
d)  PWM20. 

20. All cases of menstrual toxic shock syndrome appear to be caused by:

a)  SEA
b)  TSST-1
c)  SPE-A 
d)  SEC

21.  Toxic shock syndrome and toxic shock-like syndrome are both caused by:

a)  exotoxins synthesized by Staphylococcus aureus
b)  exotoxins synthesized by Group A Streptococcus
c)  superantigens
d)  autoantibodies

Refer to the figure below which depicts the electrophoretic separation of serum for questions 22 and 23
22.  In which of the fractions would you find immunoglobulins?
a)
b)
c)
d)

23.  In which of the fractions would you find serum albumin?
a) 
b)
c)
d)

24.  Membrane bound Ig is just one part of a complex known as the B cell receptor complex.  Additional accessory proteins are termed:

a)  Iga and Igb 
b)  CD4 and CD8
c)  Ca and  Cb
d)  CD3 and TcR     

25.  The above accessory proteins contain long cytoplasmic domains that can be phosphorylated at which of the following amino acid residues:

a)  serine
b)  tyrosine
c)  proline 
d)  asparagine

26.  Which of the following types of antigenic determinants of Ig are found within the variable region domains:

a)  isotypic 
b)  allotypic
c)  idiotypic                          

27.  Goat anti-mouse IgG would best be described as:

a)  an anti-idiotypic antibody 
b)  an anti-allotypic antibody
c)   an anti-isotypic antibody

28.  Subtle amino acid differences within the C_L and C_H regions of Ig occur due to the fact that they are encoded by different alleles.  Such antigenic determinants are termed:

a)  isotypic
b)  allotypic
c)  idiotypic

29.  Dryer and Bennet are credited with:

a)  discovering multiple myeloma
b)  explaining the structural basis of Ig diversity
c)  proving that Ig genes are rearranged in mature B cells
d)  proposing that there are separate genes which code for V and C regions of Ig

30.  The heavy chain variable region of all classes/subclasses of Ig are encoded by:

a)  V & C gene segments
b)  V & J gene segments
c)  V gene segments only 
d)  V, D, & J gene segments

31.  The antigen binding specificity of an antibody is due to:

a)  the constant regions of the light chains
b)  the variable framework regions of the heavy & light chains
c)  the variable regions of the heavy chains 
d)  the hypervariable regions of both heavy & light chains

32.  If a pre-B cell fails to productively rearrange the heavy chain genes on both chromosomes, the result is:

a)  the light chains will then attempt to rearrange
b)  the cell will undergo apoptosis
c)  the cell will begin to divide
d)  the cell will become an NK cell

33.  If the fourth polyadenylation site on a heavy chain primary transcript is utilized, which of the following types of Ig would be synthesized:

a)  membrane IgM
b)  membrane IgD
c)  secreted IgM 
d)  secreted IgD

34.  The heavy chain class switch is regulated by:

a)  T helper cytokines
b)  antigen presenting cells such as macrophages
c)  RAG 1 and RAG 2 genes
d)  none of the above

35.  If the heavy chain variable region gene segments of Ig are followed by heptamer 23 nonamer consensus sequences, then:

a)  the J segments should be preceeded by heptamer 23 nonamer sequences
b)  the D segments should by flanked on either side by heptamer 23 nonamer sequences
c)  the D segments should be preceeded by the heptamer 23 nonamer sequence
d)  a heptamer 12 nonamer sequence would be found following each J segment

36.  Terminal deoxynucleotidyl transferase activity contributes to which of the following:

a)  recombinatorial diversity 
b)  somatic mutation 
c)  combinatorial diversity
d)  junctional diversity

37.  IFN g triggers which of the following heavy class switches:

a)  IgM-----IgG1
b)  IgG1--->IgE
c)  IgM-----> IgG2a
d)  IgM----IgA2

38.  Somatic mutations occur with high frequency within Ig:

a)  CH₁ domains
b)  V_H and V_L domains
c)  CH₂ and CH₃ domains
d)  leader sequence domains

39.  k  and   l  light chain genes:

a)  are located on the same chromosome
b)  are heavy chain isotype specific
c)  can both be expressed by in the same B cell
d)  none of the above

40.  The human MHC complex is referred to as :

a)  the H-2 complex 
b)  the B complex 
c)  the HLA complex
d)  none of the above

41.  If you cross a BALB/C (H-2^d) mouse with a CBA (H-2^k) mouse, what MHC molecules will be present on individual cells of the F1?

a)  H-2^d allelelic forms only
b)  H-2^k allelic forms only
c)  either H-2^k or H-2^d allelic forms
d)  both H-2^k and H-2^d allelic forms

42.  Which of the following heavy chain class switches would NOT be possible?

a)  IgM------->IgG1                                               c)  IgG1------->IgE

b)  IgE-------->IgG1                                               d)  IgM-------->IgA1

Fill in the Blank (1pt per blank)

43.  Multiple myeloma patients excrete light chains of immunoglobulin in their urine.  These light chains have been termed..?

44.  Areas with very little variability within the variable region domains of heavy and light chains of Ig are termed..?

45.  Each individual idiotypic determinant is termed a(n)..?

The sum of all idiotypic determinants for a given Ig is termed its ..?

46.  The acronym CDR stands for..?

47.  The ability of a single B cell to simulataneously express IgM and IgD on its surface is due to..?

48.  Heptamer nonamer signal sequences are believed to be recognized by specific  enzymes known as..?

49.  The Ig heavy chain genes of only one of the homologous chromosomes is expressed in a given B lymphocyte.  This phenomenon is termed ..?

50.  The acronmym MHC stands for..?

51.  Two mouse strains which are genetically identical except at a single genetic locus are termed..?

52.  The MHC genes are inherited in 2 sets, one from each parent.  Each of these sets is referred to as a(n)..?

Short Answer Questions (point values as indicated)

53.  In the space below, list 4 of the effector functions of immunoglobulin.  (2pts)

54.  What does the acronym ADCC stand for?  (3pts)

Give two types of cells which participate in this immune mechanism.

55.  In the space below, diagram the germline configuration of the k  or   l  light chain genes of humans.

Just below the diagram, give 1 possible configuration following rearrangement.  (4pts)

56.  Diagram the germline configuration of the heavy chain genes of mouse OR human Ig.  Please show switch regions with a star.

Draw the DNA configuration which would result from one heavy class switch from IgM------IgA1  (5pts)

57.  Refer to the stick figure of IgG in the space below.  Label the polypeptide chains and show the positions of interchain disulfide bonds.

Then diagram the results of treatment of the IgG with mercaptoethanol.  Label the fragments which would be created and provide labels.

(4pts)

58.  Briefly explain the mechanism which prevents non-rearranged immunoglobulin genes from being transcribed.

(3pts)

59.  A patient has been discovered to have a genetic defect in the RAG 1 gene.  How would this defect be expected to affect the indivdual’s immune system?  Please be specific in your answer (3pts)

60.  List give the Class I gene loci for mice or humans (please indicate which type you are listing)  (2pts)

61.  Give one advantage and one disadvantage of N-nucleotide addition during the rearrangement of Ig heavy chain gene segments.  (2pts)

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