Humoral Immunity and the Generation of Antibody Diversity

Question 1

structure of an antibody

Answer 1

tetrameric proteins (2 light chains two heavy chains)

• has variable region
• has constant region (Fc) - responsible for effector functions. binds complement, phagocytes with Fc

Question 2

structure of variable region of antibody

Answer 2

3 complementarity determining regions (CDR)
in primary structure the 3 are seperate buy in final structure they align adjacent to form the structure that binds the antigen.

Question 3

where are bcells generated and developed

Answer 3

generated and develop in bm.

Question 4

what happens when a bcell is activated

Answer 4

activated by its specific antigen

differentiates into a plasma cell that proliferates and secretes Ig.

Question 5

does body design Ig

Answer 5

body does not design a specific antibody in response to a specific antigen.
body generates over 100,000,000 different B-cells each making a different random immunoglobulin, this is initially as a cell surface molecule (acting as a receptor).

Question 6

what happens when bcell are activated

Answer 6

are activated and begin to multiply. this is clonal selection and expansion.
some activate cells become memory cells some become plasma cells which secrete Ig

Question 7

what is required by a bcell to mount an immune response

Answer 7

must bind to cd4 tcells and the release of cytokines.

Question 8

how does genome encode so many Ig

Answer 8

there is no complete Ig gene, rather Ig gene segments that in different combinations produce different Ig

Question 9

how does genome encode so many Ig using kappa light chain as an example

Answer 9

any given cell contains KCL gene. this contains one constant region (C)35 variable regions (V) 5 joining regions (J)
is an endonuclease binding site immediately after every V segment & in front of each J segment. randomly cut after V segment and before J segment. this DNA discarded. In this way dsDNA joining allows us to choose certain parts of DNA to transcribe.