immunology - tik26

[ArchivalUser]

Now those 2

1) Which of the following genes involved in the synthesis of immunoglobulins are linked on a single chromosome?


A. C gene for gamma chain and C gene for alpha chain

B. C gene for gamma chain and C gene for kappa chain

C. V gene for kappa chain and C gene for the epsilon chain

D. V gene for lambda chain and C gene for kappa chain

E. V gene for lambda chain and V gene for heavy chain


2)A 30 year-old man comes to medical attention because of fevers and night sweats. CT scan reveals masses involving the mediastinal nodes, abdominal nodes, and liver. Biopsy of one of the nodes demonstrates a nodular lymphoma with nodular areas composed predominately of small (6-12 micrometer) lymphocytes with scanty cytoplasm and irregular, twisted, and indented nuclei. This lymphoma is most closely linked to a translocation involving which of the following?
A. Immunoglobulin heavy chain and bcl-1
B. Immunoglobulin heavy chain and bcl-2
C. Immunoglobulin heavy chain and myc
D. Kappa immunoglobulin light chain and myc
E. Lambda immunoglobulin light chain and myc

[ArchivalUser]

1. d
2. b

[ArchivalUser]

2 is b but try again 1

2)The correct answer is B. The lymphoma described in the question stem is the follicular type of small cleaved cell (B cell) lymphoma, and its characteristic translocation is t(14;18)(q32;q21). The site on chromosome 14 involves the heavy chain of immunoglobulins (IgH), while that on chromosome 18 involves the bcl-2 oncogene. The translocation produces a hybrid bcl-2/immunoglobulin heavy-chain transcript.
A t(11,14)(q13;q32) translocation involving bcl-1 and IgH (choice A) is seen in small non-cleaved lymphocytic lymphoma, myeloma, and some mantle cell lymphomas.

Burkitt's lymphoma is usually associated with t(8;14) (myc and IgH; choice C), but sometimes with t(2;8) (kappa immunoglobulin light chain and myc; choice D) or t(8;22) (lambda immunoglobulin light chain and myc; choice E).

[ArchivalUser]

Hi, okt3

A. two heavy chain

[ArchivalUser]

hello durham, u r correct

The correct answer is A. The genes for the synthesis of the entire heavy chain are present on human
chromosome 14. Of the options given above, the only genes that are present on one chromosome are for the
C (constant) regions of the heavy chains. Remember, the heavy chains determine the identity of the
immunoglobulin isotypes: IgG, IgM, IgA, IgD, and IgE.

Choice B: The C gene for the gamma heavy chain is on chromosome 14 and the C gene for the kappa light
chain gene is on chromosome 2.

Choice C: The V gene for the kappa light chain gene is on chromosome 2. The C gene for the epsilon heavy
chain is on chromosome 14.

Choice D: The V gene for the lambda light chain gene is on chromosome 22. The C gene for the kappa light
chain gene is on chromosome 2.

Choice E: The V gene for the lambda light chain gene is on chromosome 22 and the V gene for the heavy
chain gene is on chromosome 14.