Week 2

Question 1

Genes for immunoglobulins are unlike other human genes in that

Answer 1

somatic recombination occurs before mRNA is transcribed

and there is less Ig genetic material in mature B cells than in other somatic cell

Question 2

The gene segments needed to encode the variable region of a k chain are

Answer 2

one Vk plus one Jk.

Question 3

Combinatorial diversity says that by random combination of 40 functional Vk segments with five Jk segments, the number of possible different k chains that could be made are

Answer 3

200

Question 4

Since each B cell productively rearranges a single H and L chain allele, it exhibits

Answer 4

allelic exclusion

Question 5

Primary mRNA for H chain encodes

Answer 5

one VH, one DH, and multiple JH segments.

Question 6

Somatic recombination occurs

Answer 6

in the progenitor cell as it is becoming a B cell.

Question 7

Alternative mRNA splicing

Answer 7

is a process by which a B cell can simultaneously synthesize m and d chains.

Question 8

B cell differentiation begins with the expression of

Answer 8

RAG-1, RAG-2 and TdT.

Question 9

secrete cytokines such as IL-7 that signal developing B cells to divide and differentiate.

Answer 9

Bone marrow stromal cells

Question 10

The developmental step that commits a cell to the B lineage is

Answer 10

joining of a DH gene segment to a JH gene segment

Question 11

Once H chain genes have been productively rearranged and expressed on the pre-B cell membrane, the next event to occur in the cell is

Answer 11

proliferation of the pre-B cells.

Question 12

f a B cell tumor is monoclonal, it can be differentiated from normal B cells of the same person by its unique membrane Ig

Answer 12

idiotype

Question 13

If you wanted to check for the presence of memory B cells from your vaccine subjects by taking some of their B cells and re-stimulating them in vitro (outside the body) with antigen, the best place to get some memory cells would be from

Answer 13

blood

Question 14

VDJ rearrangement on ‘H’ chain occurs in what B cells to produce Heavy chain.

Answer 14

Pro-B cells

Question 15

VJ rearrangement on ‘L’ chain occurs in what cells to produce Light chain.

Answer 15

Pre-B cells and is arranged in Immture B cells

Question 16

After the re-arrangement, the B cells are now called

Answer 16

Immature B cells

Question 17

There are 4 mechanisms in which B cells generate receptor diversity:

Answer 17

Somatic recombination:
VDJ recombination for heavy chain
VJ recombination (No “D” segment) for light chain
Pairing of various light chains with heavy chains
Junctional diversity (nucleotide addition via Tdt)
Somatic hypermutation (single point mutation in antibody idiotype)

Question 18

During differentiation of this cell into the B-cell, rearrangement of the DNA occurs. This rearrangement aligns __ of the __ V genes with __ of the D genes and __ of the J genes, producing a functional VDJ recombinant gene. Since any of the genes may recombine with any others, this rearrangement has the potential to generate__ V x __D x __J = 6000 different possible combinations.

Answer 18

1 of the many (40) V with 1 of the D and 1 of the J

40 V, 25D, 6 J

Question 19

cells work closely with macrophages to provide the elegance and complexity of immune function?

Answer 19

Lymphocytes

Question 20

Major histocompatibility complex antigens are found on all human cells with the exception of what type of cells?

Answer 20

RBCs

Question 21

Of the MHC genes, which codes for receptors that recognize and react with foreign antigens?

Answer 21

Class II MHC

Question 22

hat class of MHC receptors is found on the surface of all nucleated cells?

Answer 22

Class I MHC

Question 23

What is the process by which lymphocyte clones that develop a specificity for self molecules are eliminated or deleted from the pool of genetic diversity?

Answer 23

Immune Tolerance

Question 24

What leads to the extreme variations in the expression of specific receptors in lymphocytes?

Answer 24

clonal selection

Question 25

What is the process by which lymphocyte clones that develop a specificity for self molecules are eliminated or deleted from the pool of genetic diversity?

Answer 25

Immune tolerance

Question 26

Immunoglobulin heavy (H) chains genes are composed of genes from what segments of the genome?

Answer 26

VDJC

Question 27

What is the function of interleukin-1 (IL-1)?

Answer 27

IIt activates T helper cells that have recognized processed and presented antigen.

Question 28

Once a B cell has processed and presented an antigen, what event must occur before it becomes activated?

Answer 28

The B cell must bind to an activated T helper cell that has receptors for the same antigen.

Question 29

What antibody is a significant component of the mucous and serous secretions of the salivary glands, intestine, nasal membrane, breast, lung, and genitourinary tract?

Answer 29

Dimeric IgA

Question 30

What is the mode of action of T cytotoxic cells?

Answer 30

They secrete perforins that create pores in the membrane of a target cell.

Question 31

What type of cell is fused with a myeloma cell when producing a hybridoma?

Answer 31

Plasma cells

Question 32

Which of the following is an example of artificial passive immunity?

Answer 32

A person who receives immune serum during treatment for hepatitis