How does Allelic exclusion helps us stay alive?
Stay tuned for the details.
First, I want to go over what an allele is.
An allele is a particular form of a certain
gene and it is located on a chromosome.
For example, there are different alleles for
hair color or eye color.
Humans are diploid, meaning that they have
two sets of chromosomes.
You get one set from your mother and one set
from your father.
If both alleles are the same, you are homozygous
for that trait, if the alleles are different,
you are heterozygous.
In allelic exclusion, one allele is excluded
and does not get expressed, while the other
allele is solely expressed.
This is good in terms of immunology.
B cells are a part of your immune system and
one of their roles is to create antibodies.
As they go through the process of creating
antibodies, they have to arrange and rearrange
genes in order to produce an antibody that
will work.
If the antibody doesn’t work, the B cell
will be destroyed.
The stages that a B cells goes through as
it attempts to arrange an antibody are: stem
cell, early pro-B cell, Late pro-B cell, large
pre-B cell, small pre-B cell, innate B cell,
and mature b cell.
The heavy chain of the antibody is rearranged
before light chain rearrangement begins.
While the heavy chain is being arranged, at
a certain point, it uses surrogate light chains.
For the variable region, it uses VpreB and
for the constant region, it uses lambda 5.
At a certain point, such as the large pre-B
stage, rearrangement of the heavy chain will
stop and this will ensure that the antibodies
on the b cell express only one allele and
express only one specificity.
Do not confuse this process with antibody
diversity; the purpose of allelic exclusion
is to ensure that the receptor on the antibody
has one specificity.
For antibodies, you want things to be very
specific, so that mistakes are not made in
the body.
The specificity will ensure that if the antibody
encounters the antigen that is supposed to
stick to, that it will more likely stick to
it, and it the antigen and the pathogen that
it originates from, will be eliminated.
This helps us to stay alive.
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