Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

24 Cards in this Set

  • Front
  • Back
How can we produce millions of different Abs with limited genes?
Ig gene rearrangement
Discovery of gene rearrangement
Susumu Tonegawa – 1976 (won Nobel in 1987)
showed that DNA segments containing the Ig genes differed in size when comparing the germ-line (sperm) and in mature myeloma cells
gene segments of the Heavy Chain in Germ line DNA of B cells (immature B cells)
V(ariable), D(iverse), J(joining) and C(constant) region genes
gene segments of the Light Chain in Germ line DNA of B cells (immature B cells)
V, J, and C region genes
_______ make up the variable region of the antibody
V,D& J
Genes must be ________ in order to be functional genes that can code for an Ab. This is a _____ of the genes used is______ AND occurs before Ag stimulation
rearranged, Selection, random
Class switching
After Ag stimulation, a mature B cell can change it’s isotype
Location of genes for lambda and kappa light chain and heavy chain are all on different chromosomes for the purpose of __________
To achieve Ig specificity,_______ can be expressed at once
only one allele
Allelic exclusion
during the process of Ig gene rearrangement, if the first allele is successful, then the process stops
if the first allele is non-productive, then the other allele will be re-arranged
The process of gene rearrangement is “tightly” controlled and occurs in a very specific order
H-chain first, the k light chain, then l light chain (if needed)
Overview of B cell development in bone marrow
Start with a hematopoetic stem cel l(pluripotent) which based on colony stimulating factors differentiates into a lymphoid cell, specifically a B cell, you rearrange heavy chain first, once that is complete you rearrange light chain, once that is completed you have an immature B cell that can first express membrane IgM. Soon after that the mature B cell will coexpress membrane IgM & IgD. This cell is called a MATURE B CELL & a NAÏVE B CELL (because it’s never seen Ag before).
Overview of B cell development in the peripheral lymphoid organs upon Ag Stimulation
Mature B cell gets stimulated by Antigen, a lot of things can happen at this point depending on cytokines in the environment. B cell becomes activated to become a plasma cell if it is a primary immune response it secretes IgM. Depending on cytokines you can get memory cells that are able to class switch and produce IgG, IgA, IgE, depending on on enviornment.
Describe heavy chain Ig rearrangement
-DH and JH join, then V with DHJH yielding a VDJ DNA sequence
-Then C region selection occurs IgM is first, followed by co-expression of IgD, only “normal” time B cell expresses two isotypes
How to select ONE V,D,J region and not two or more?
recombination signal sequences (RSS)
-12/23 bp rule – a 12 bp sequence can join with a 23 bp sequence
12/23 bp rule
V—23; D-12
Enzyme responsible for 12-23 BP rule
RAG =recombination activating genes
V(D)J recombinase
the complex of enzymes important in recognizing and excising the intervening sequences (looping out)
Allelic exclusion
A given B cell will express ONE heavy chain Ag specificity and ONE light chain Ag specificity
Humans have two IgH alleles and four IgL chain alleles (2 for k and 2 for l)
-Can express
maternal/paternal; or
How many shots do you have to get a successful heavy chain
2 (1 for each parental allel)
How many shots do you have to get a successful heavy chain
4 (1 for each parental K & L allele )
Generation of Diversity - Ig
-Multiple germ-line gene segments (V, D, J)
e.g. 65 VH, 27 DH, 6 JH

-Combinatorial V-(D)-J joining
Joining of a V region to a particular D and then to a J
e.g. VH32 with DH15 with JH2 OR VH32 with DH8 with JH2
-some examples of VDDJ and VDDDJ in H-chains (rare)

Combinatorial association of light and heavy chain
an Ag can interact with either the L-chain, the H-chain or the combination of the two
Therefore, joining a particular H-chain with a L-chain = diversity

Junctional flexibility
imprecise joining together of the V-D-J or V-J regions
Somatic hypermutation is localized to which area of the the CDRs in heavy and light chains
CDR3 for IgH

CDR1 for IgL
Affinity maturation
Because a B cell that binds it’s Ag is most likely to be selected (= proliferation); it will also have the most variability (highest chance for somatic hypermutation)
Igs with highest affinity for Ag will be selected
these Ag specific B cells will then mutate and potentially generate higher and higher affinities