In very simple
drawings are not to ratio - just comparisons)
Not all the
parts of a cell are pictured or talked about here........
in the process of conception
Inside the cell
is the nucleus where the 23 pair of chromosomes reside. Also inside the
cell but not in the nucleus is the MTDNA.
nucleus of a cell
Here I have used
different colors to indicate the 23 pairs of chrosomes. Notice the pair
that is not the same color. A blue and a pink?
those are not the same color because they are not the same even though
they are a pair. They represent the Y and the X chromosome. A pair but not
the same. The others are the 22 pairs of Autosomal chromosomes. The
autosomal chromosomes combine and recombine at each conception. When the
egg impregnates, the autosomal chromosomes of the egg and the sperm do a
little dance with each other and combine with the
same Markers. While some SNP markers are discarded others remain in
segments. (It is all random) The 23 and me test looks for segments
that are a certain size and and larger.
autosomal chromosomes do their little dance, the Y and X pair up; but if a
girl child an XX instead of YX, then they do a dance of recombination too.
Now since the Y
chromosome has no one to combine/recombine with, he virtually stays the
same with very few changes in any of the different markers within the
chromosome. Mutations or changes in the markers is always random and
happen at different rates for different markers. Changes do happen, faster
with the STR markers then with the slower changing SNP markers.
but very different
The MTDNA has a
primary job that is as important as the genetic history of the cell, but
much different. MTDNA as you can see from the pictures does not reside in
the nucleus. It is within each individual cell. MTDNA's job is the
creation, direction and use of energy, without energy .. our cells would die!
While the shape of
any of the nucleus chromosome pairs is a string, the shape of the mtdna chromosome
is circular. it has about 17000 base pairs that are tested. The tested
areas are normally HVR1 and HVR2 and the rest is coding zone. If you look
at a clock HVR1 and HVR2 are from 11:59 to about 12:06 the rest of the
clock is coding zone.
Hope this helps as
some people understand better when they can see or picture the item.