Comment
Thank you V.H.!! Your explanation helped me immensely. You have the traits of a great teacher.... Mary Garana Allen
"v.h.villarreal" <raices_regias@...> wrote:
"v.h.villarreal" <raices_regias@...> wrote:
Josie,
At the risk of oversimplifying this whole thing, I'm posting a few
essential concepts about DNA. Please excuse me if I sound patronizing.
We all have heard that DNA is the blueprint of life. And it is! Or
to be more exact, each organism's DNA is its own blueprint of life.
Just think how it is possible to clone an animal (make an exact
genetic replica) from the DNA found in the nucleus of a single cell.
And notice that in theory a clone could be made from practically every
cell in the body, as most cells have a copy of all their DNA, their
full genome.
Although each cell with a nucleus has their full genome it only has a
small section of it activated, the specific section that contains the
instructions that each cell must carry out. Imagine a huge theater
performance with many, many actors, where every
actor has a copy of
the whole script but some actors only have to read a few lines or a
few pages at most. So it is with cells; each one has differentiated
to play a specific role in the body.
We could say, for practical purposes, that for each cell's role or
function a set of instructions are written and stored in a gene.
There are many things that cells do and therefore there are many
genes. These genes in turn are packaged into chromosomes of which
human cells have 46. These cells with 46 chromosomes are called
diploid cells.
Since we're not clones, half of those 46 chromosomes come from each of
our progenitors. 23 from the father and 23 from the mother to make 23
pairs. Every chromosome is of equal size to its pair except in males
where the 23rd pair or the XY is an uneven pair. There's a section in
the Y chromosome that is unmatched in the X chromosome and it is
called a
non-recombining section or segment.
Like I said above, every cell in the body has two sets of chromosomes
or a total of 46, but there's an exception: reproductive cells.
Reproductive cells only carry 23 single chromosomes or half the number
of other cells and they are called haploid cells. But each of these
chromosomes in reproductive cells are a combination of the
corresponding chromosome pair in diploid cells.
Since Y chromosome has an unmatched segment that doesn't recombine
with the X chromosome, this segment passes almost unaltered from
generation to generation (but only in the male line or patrilineal
ancestry). These non recombining sections of the Y chromosome are
what genetic labs analyze in the now famous YDNA tests.
The other 22 pairs of chromosomes or the autosomal DNA from both
progenitors do recombine and shuffle their genes before creating a
single set of chromosomes in reproductive cells.
In other words, out
of our full genetic material our reproductive cells can only carry on
and pass to our children half of it. But in contrast to what we
receive: half from our mother and half from our father, we do not
necessarily pass on to our progeny the same proportions we receive
from each. And furthermore, each reproductive cell can have a
different proportion or combination of genetic material from our
progenitors, otherwise all our children would be identical. Makes
sense? That is why it is so difficult to trace the genetic lineage of
any other of our ancestors besides the Y lineage. Yet, we can tell
when a child gets a trait from his/her grandpa or her/his grandma, etc.
Mitochondrial DNA is a whole different story. To start with, some
people think that mtDNA is part of our chromosomes but it is not. Like
chromosomal DNA, mtDNA is also in the cells but it is found only in
the protoplasm not in the
nucleus. Mitochondrial DNA is not strictly
human. Biologists believe that millions of years ago human cells and
mitochondrial cells created a symbiosis or mutually beneficial
association. Human cells provide the nutrients mitochondria need and
these in turn provide the energy the human cells need to carry out all
their functions. None can live without the other.
I started out saying that DNA is the blueprint of life and I was
referring to chromosomal DNA from both parents. But to build a human
being, like building a house or anything else, you not only need a
blueprint but also the raw materials and a lot of energy. These raw
materials and energy always come from the mother, because only females
get pregnant and give birth. In fecundation and conception the male
only provides one cell; all the mitochondrial "machinery" is provided
by the female.
So you can see, mtDNA is strictly inherited
thru the maternal line.
And when a mutation ocurrs in mtDNA all offspring inherit the same
distinctive mutation. But mutations in mtDNA are much more rarer than
mutations in YDNA, therefore a single mismatch in mtDNA can mean a
shared ancestor many, many generations ago, beyond the conventional
genealogical framework. This is our deeper ancestry link!
Saludos,
Victor
--- In ranchos@yahoogroups.com, "Josie T. Trevino" <Josiett3@s...> wrote:
>
> Hi!
>
> Someone once explained to me that the mtDNA results were, in some
cases, the
> result of Spaniards marrying the "local girls" ........is this what
you are
> referring to, Arturo? I do not understand these numbers.....I am just
> trying to make heads or tails out of it......and to justify the $$$$
I spent
> to get these numbers! :-)
> Seriously, I don't mind spending
the money if it will give me some
clues as
> to my ancestors, the migration pattern they followed, etc. I have only
> researched about three or four generations on my Dad's maternal line and
> three or four on my Mom's maternal and paternal lines so I have a
long way
> to go. I have been focusing on my Dad's paternal Trevino lineage and go
> "way back" to about the 1400s in Spain.
>
> I really enjoy reading the messages everyone is sending regarding
Y-DNA and
> mtDNA because I am slowing learning a little here and there. What I
really
> like is finding out that I have matches to a few in this group, Linda,
> Victor, Arturo and an exact match with Ed! Even though I have never
met any
> of you in person I do feel a connection! The only grandparent I
knew was
> my Mom's father and he died when I was 7 years old. My
other
grandparents
> died before I was born. I only have one brother so you can see that my
> familia is very small.......maybe that is why I am always looking
for "mi
> gente!" I have met several primos and primas (live ones!) through
> genealogy and it feels good when we share information and discover
that our
> great-grandparents were brothers/sisters and here we are digging up
their
> information!
>
> It would be wonderful if a group were started concentrating on mtDNA.
>
> Josie in San Antonio
>
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Please see comments below: Elvira
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Emilie.......I feel so much better reading your post! I was beginning to think I was developing "Juvenile Alzheimer's"........I also remember something about this in school......and.....also "so very long ago!" :-) Thanks for making me feel better! Josie in San Antonio From: ranchos@yahoogroups.com [mailto:ranchos@yahoogroups.com] On Behalf Of Emilie Garcia Sent: Saturday, November 19, 2005 1:03 AM To: ranchos@yahoogroups.com Subject: Re: [ranchos] mtDNA and other DNA Wow, Victor, I printed out your wonderful explanation below. I think I am beginning to grasp something. I remember learning something about chromosomes from school so very long ago. Also, the man next door talked about some monster criminals, murderers, who were shown to be "YY". I thought I recalled that men were "XY" and women were "XX". YY's would be genetic monsters, no? They should be locked up or killed. They are not really human if they exist. I wonder if my neighbor was joking. I know that often I don't get the jokes. Emilie Garcia Port Orchard, WA ---
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color=#0000ff size=2>Victor......thanks for the explanation on DNA, and you do
not sound patronizing. I appreciate the detail that you provide regarding
DNA. I have been so involved in searching for my ancestors
that I never gave DNA a thought until now. This adds more flavor to
the research that I love!
not sound patronizing. I appreciate the detail that you provide regarding
DNA. I have been so involved in searching for my ancestors
that I never gave DNA a thought until now. This adds more flavor to
the research that I love!
color=#0000ff size=2>
color=#0000ff size=2>I noticed that I only have four "HVR1 differences from CRS"
(mutations) in my mtDNA results posted on the database for Family Tree DNA while
others have five, six and more. What does this indicate? I
understand that the CRS is used as a basis for comparison with mtDNA and that,
in my case, I have four instances of differences from the CRS.......what I do
not understand is......is this a good thing? :-) Am I trying
to read too much into this?
(mutations) in my mtDNA results posted on the database for Family Tree DNA while
others have five, six and more. What does this indicate? I
understand that the CRS is used as a basis for comparison with mtDNA and that,
in my case, I have four instances of differences from the CRS.......what I do
not understand is......is this a good thing? :-) Am I trying
to read too much into this?
color=#0000ff size=2>
color=#0000ff size=2>Thanks again, Victor, for your help......and thanks to the
other members of this group who have helped me! I appreciate
it!
other members of this group who have helped me! I appreciate
it!
color=#0000ff size=2>
color=#0000ff size=2>Josie in San Antonio
From:
ranchos@yahoogroups.com [mailto:ranchos@yahoogroups.com] On Behalf Of
v.h.villarreal
Sent: Friday, November 18, 2005 9:51
PM
To: ranchos@yahoogroups.com
Subject: [ranchos] mtDNA and
other DNA
ranchos@yahoogroups.com [mailto:ranchos@yahoogroups.com] On Behalf Of
v.h.villarreal
Sent: Friday, November 18, 2005 9:51
PM
To: ranchos@yahoogroups.com
Subject: [ranchos] mtDNA and
other DNA
Josie,
At the risk of oversimplifying this whole thing,
I'm posting a few
essential concepts about DNA. Please excuse me if I sound
patronizing.
We all have heard that DNA is the blueprint of life.
And it is! Or
to be more exact, each organism's DNA is its own
blueprint of life.
Just think how it is possible to clone an animal (make an
exact
genetic replica) from the DNA found in the nucleus of a single cell.
And notice that in theory a clone could be made from practically
every
cell in the body, as most cells have a copy of all their DNA,
their
full genome.
Although each cell with a nucleus has their full
genome it only has a
small section of it activated, the specific section that
contains the
instructions that each cell must carry out. Imagine a huge
theater
performance with many, many actors, where every actor has a copy
of
the whole script but some actors only have to read a few lines or a
few
pages at most. So it is with cells; each one has differentiated
to play
a specific role in the body.
We could say, for practical purposes,
that for each cell's role or
function a set of instructions are written and
stored in a gene.
There are many things that cells do and therefore there
are many
genes. These genes in turn are packaged into chromosomes of
which
human cells have 46. These cells with 46 chromosomes are
called
diploid cells.
Since we're not clones, half of those 46
chromosomes come from each of
our progenitors. 23 from the father and
23 from the mother to make 23
pairs. Every chromosome is of equal size
to its pair except in males
where the 23rd pair or the XY is an uneven
pair. There's a section in
the Y chromosome that is unmatched in the X
chromosome and it is
called a non-recombining section or segment.
Like I said above, every cell in the body has two sets of
chromosomes
or a total of 46, but there's an exception: reproductive cells.
Reproductive cells only carry 23 single chromosomes or half the number
of
other cells and they are called haploid cells. But each of
these
chromosomes in reproductive cells are a combination of
the
corresponding chromosome pair in diploid cells.
Since Y chromosome
has an unmatched segment that doesn't recombine
with the X chromosome, this
segment passes almost unaltered from
generation to generation (but only in
the male line or patrilineal
ancestry). These non recombining sections
of the Y chromosome are
what genetic labs analyze in the now famous YDNA
tests.
The other 22 pairs of chromosomes or the autosomal DNA from
both
progenitors do recombine and shuffle their genes before creating
a
single set of chromosomes in reproductive cells. In other words,
out
of our full genetic material our reproductive cells can only carry
on
and pass to our children half of it. But in contrast to what
we
receive: half from our mother and half from our father, we do
not
necessarily pass on to our progeny the same proportions we
receive
from each. And furthermore, each reproductive cell can have
a
different proportion or combination of genetic material from
our
progenitors, otherwise all our children would be identical.
Makes
sense? That is why it is so difficult to trace the genetic
lineage of
any other of our ancestors besides the Y lineage. Yet, we
can tell
when a child gets a trait from his/her grandpa or her/his grandma,
etc.
Mitochondrial DNA is a whole different story. To start with,
some
people think that mtDNA is part of our chromosomes but it is not.
Like
chromosomal DNA, mtDNA is also in the cells but it is found only
in
the protoplasm not in the nucleus. Mitochondrial DNA is not
strictly
human. Biologists believe that millions of years ago human
cells and
mitochondrial cells created a symbiosis or mutually
beneficial
association. Human cells provide the nutrients mitochondria
need and
these in turn provide the energy the human cells need to carry out
all
their functions. None can live without the other.
I started
out saying that DNA is the blueprint of life and I was
referring to
chromosomal DNA from both parents. But to build a human
being, like
building a house or anything else, you not only need a
blueprint but also the
raw materials and a lot of energy. These raw
materials and energy
always come from the mother, because only females
get pregnant and give
birth. In fecundation and conception the male
only provides one cell;
all the mitochondrial "machinery" is provided
by the female.
So you
can see, mtDNA is strictly inherited thru the maternal line.
And when a
mutation ocurrs in mtDNA all offspring inherit the same
distinctive
mutation. But mutations in mtDNA are much more rarer than
mutations in
YDNA, therefore a single mismatch in mtDNA can mean a
shared ancestor many,
many generations ago, beyond the conventional
genealogical framework.
This is our deeper ancestry link!
Saludos,
Victor
---
In ranchos@yahoogroups.com, "Josie T. Trevino" <Josiett3@s...>
wrote:
>
> Hi!
>
> Someone once explained
to me that the mtDNA results were, in some
cases, the
> result of
Spaniards marrying the "local girls" ........is this what
you are
>
referring to, Arturo? I do not understand these numbers.....I
am just
> trying to make heads or tails out of it......and to justify the
$$$$
I spent
> to get these numbers! :-)
>
Seriously, I don't mind spending the money if it will give me some
clues
as
> to my ancestors, the migration pattern they followed, etc. I
have only
> researched about three or four generations on my Dad's
maternal line and
> three or four on my Mom's maternal and paternal lines
so I have a
long way
> to go. I have been focusing on my Dad's
paternal Trevino lineage and go
> "way back" to about the 1400s in
Spain.
>
> I really enjoy reading the messages
everyone is sending regarding
Y-DNA and
> mtDNA because I am slowing
learning a little here and there. What I
really
> like is finding
out that I have matches to a few in this group, Linda,
> Victor, Arturo
and an exact match with Ed! Even though I have never
met any
> of
you in person I do feel a connection! The only grandparent I
knew
was
> my Mom's father and he died when I was 7 years old. My
other
grandparents
> died before I was born. I only have one
brother so you can see that my
> familia is very small.......maybe that is
why I am always looking
for "mi
> gente!" I have met
several primos and primas (live ones!) through
> genealogy and it feels
good when we share information and discover
that our
>
great-grandparents were brothers/sisters and here we are digging
up
their
> information!
>
> It would be
wonderful if a group were started concentrating on mtDNA.
>
>
Josie in San Antonio
>
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