AMC: Comments on AMC and Notes on my Travels
tamara skaredoff
hope this works...
the genes for ble eyes are recessive while the genes for brown eyes are
dominant (i could never figure out where green, etc fir into this scheme
of things...) so anyone who has blue eyes cannot be carrying the genes for
blue eyes, but brown-eyed people can have the genes for blue eyes. this
is grossly oversimplifies, because my understanding is grossly over simple,
and beverly is probably right, that it isn't totally impossible, but it is
an
anomaly for two blue eyed parents (though brroke sometimes has green eyes...)
to have a brown-eyed child
-t
sorry, that's blue-eyed people can't carry the genes for brown eyes...
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Granma
>kar...@ssd.intel.com (Karin Coffee) writes:
>>
>> Something that's been bugging me for awhile. Brooke has blue eyes. Tad
>> has blue eyes. Jamie has brown eyes. That's genetically impossible.
>> I know it's a nit, but it's been niggling for a long time.
>>
>So when genetics are concerned, I'll never discount the impossible!
>
>Beverly "I'd a never believed it...." H.
Beverly - YES YES YES!
My ex-BH (butt head) has blue eyes. I've got brown eyes.
Matt (son) has brown eyes, Kelly (daughter) has blue eyes.
So, even tho it ain't the same as same--eye-color parents
having children with different eye color, it's still within
the same ballpark.
Granma "Bear the wonder lab has brown eyes too........:-)"
*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-*
| "Other than that, Mrs. Lincoln, how was the play?" |
| ------------------------------------------------------ |
| Suppose that you were an idiot |
| and suppose you were a member |
| of Congress |
| But I repeat myself.... |
| --Mark Twain |
*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-*
Amanda T Marlowe
kid debate...
(Well, it was either that or actually do work, you know ;) )
My understanding of it : It is, while not impossible, extremely
unlikely that two blue-eyed parents can have a brown-eyed kid.
The other way (brown eyed parents --> blue eyed kid) is more possible,
and mixed eyed parents can have either, depending on the genetic history
of the brown-eyed parent.
My source about the blue-eyed parents having a brown-eyed kid being next to
but not completely impossible? Well, not a really good one, I admit, it was
the key to some mystery story I read somewhere, where a brown-eyed kid got
a high school course in genetics and looked at her two blue-eyed parents, and
then I don't actually remember what happened. (Anyone know this story? I
don't remember the title OR the author, but recall it sounded like they
had done their genetics homework.) Anyway, I think they gave the actual
probability in there somewhere. Take it how you will. I remember what the
scenario had to do with the solution (which I won't say, in case you run
across it, I know there are lots of mystery readers out there!) but nothing
else about the plot, like who got killed, etc...
So...
Since Jamie is a "miracle baby" to start with, give him the added "miracle"
of brown eyes.
Or maybe TAD always wore blue contacts and never told anyone, and that he'll
eventually take them out so he can be distinguished from TED once Ted gets
into a suit, tie, money, and conniving ways....
Or maybe Tom REALLY IS Jamie's father.... Now wouldn't that be a switch...
On other genetic issues: Who thinks that a simple blood test will confirm that
the baby cannot be Derrick's? This is simpler than eye color :) Say he and
Mimi are both O+ and Lucas is either AB- or some such thing? Will Mimi find
out she needs those shots if she and the baby have different RH factors?
Or has she already found that out? Is that why she's so hyper about it???
Amanda
--
** Amanda Marlowe | WARNING:Scientists have determined that research
mar...@jhunix.hcf.jhu.edu| can be hazardous to your health, and has been
** | known to cause cancer in laboratory animals.
Stephanie
mar...@jhunix.hcf.jhu.edu (Amanda T Marlowe) writes...
>Just had to add my two cents worth on the blue-eyed parents with a brown-eyed
>kid debate...
well, gotta add my 2 pesos in too..
Does anyone know if the people in question wear tinted contact lenses?
:)
-Stephanie
Judi Geistlinger
To be honest, I cannot remember whom we are talking of, but if Brooke is one
of the parties in question, I am certain she wears contacts. She has had
brown eyes in the good ole days, then blue then green.
Judi
--
Judi Geistlinger
j-geis...@uiuc.edu
CHERYL ANN DOUGHERTY
s.edu writes:
>This reminds me of when I was trying to conceive (hmmmm, hope nobody's newsfeed
>stops there!). Anyway, I was prescribed a very mild fertility drug (Clomid for
>those who are wondering) and it had the side-effect of an extremely slightly
>higher chance of twins. So, to amuse myself, I went and read up on twins.
>And a woman actually gave birth to twins with different fathers! Like this:
>two eggs were released. She had sex with two different men within a 24 hour
>period and the two eggs were fertilized by two different men thus twins with
>different fathers -- one twin was black and the other white. Now, what was it
>you all were saying a few weeks back about Mimi, Derek and Lucas....?
Well, Mimi is big enough that Taylor noticed that she must be farther along
than she says she is. Maybe this IS an indication that Mimi is expecting
twins. And, I seem to remember RATS posters proposing the twins with separate
fathers idea four months ago. Who knows?
--Cheryl
>
>Debbie
Donna Wicks
>Just had to add my two cents worth on the blue-eyed parents with a brown-eyed
>kid debate...
>(Well, it was either that or actually do work, you know ;) )
>My understanding of it : It is, while not impossible, extremely
>unlikely that two blue-eyed parents can have a brown-eyed kid.
>The other way (brown eyed parents --> blue eyed kid) is more possible,
>and mixed eyed parents can have either, depending on the genetic history
>of the brown-eyed parent.
>My source about the blue-eyed parents having a brown-eyed kid being next to
>but not completely impossible? Well, not a really good one, I admit, it was
>the key to some mystery story I read somewhere, where a brown-eyed kid got
>Or maybe Tom REALLY IS Jamie's father.... Now wouldn't that be a switch...
>--
>** Amanda Marlowe | WARNING:Scientists have determined that research
> mar...@jhunix.hcf.jhu.edu| can be hazardous to your health, and has been
>** | known to cause cancer in laboratory animals.
Well if someone does remember this book, I would love to read it.
There is no way for two blue-eyed parents to have a brown-eyed
baby. The gene possibilities just aren't there. Brooke and Tad
could have one bronw-eyed parent that carried a blue-eyed gene,
but once a blue-eyed person in conceived the ONLY gene they
carry for eye color is recessive. Here is what Tad and Brooke
could have had if one parent was blue (or green-eyed) and the
other brown-eyed.
Brown-eyed Parent: Bb (or could be BB)
Blue-eyed Parent: bb (only this combo can happen because
a dominant brown-eyed gene always
determines eye color - sort of
like a Royal Flush always wins :) )
So these two parents could produce the following four possibilities:
Bb bb
Bb bb
(You match each gene from one parent with the other to get the above)
Now on the left-hand side the child will be brown-eyed and on
the right-hand side, the child will be blue-eyed. But once the
blue-eyed child is conceive the only gene it carries for eye color
is recessive and therefore can never determine eye color except
when matching with another recessive gene. So Brooke and Tad are both
bb people and can not produce a brown-eyed child.
Look forward to reading a book that proves otherwise ...
Donna "I only paly a biologist on the net" Wicks
Karen Vahtra
Amanda T Marlowe says:
Just had to add my two cents worth on the blue-eyed parents with a brown-eyed
kid debate...
Well, it does happen. Both of my parents are blond-blue eyed, as I am also. My
sister is brown-brown-eyed! And her hair is quite dark, as are her eyes!
I remember when I took genetics, I teased her that she was adopted - we weren't
particularly nice to each other. If her features weren't so similar to mine,
I would have believed the mailman was involved.
Karen
Karen Vahtra
There is no way for two blue-eyed parents to have a brown-eyed
baby. The gene possibilities just aren't there. Brooke and Tad
could have one bronw-eyed parent that carried a blue-eyed gene,
but once a blue-eyed person in conceived the ONLY gene they
carry for eye color is recessive.
Ah, but the secret (I think) is that there is more than just one
gene for eye color. Its more complicated than that! (Read my
earlier post on my sister)
Karen
AJ
This is true! and just for Karinc since we talked about this at
the get-together, here is the scoop straight from my biology book!
The second paragraph and final sentence are the kickers:
Human eye color is a trait that was poorly understood by classical
geneticists. In 1907, an interesting research paper by Gertrude and
Charles Davenport, titled "Heredity of Eye-Color in Man," appeared
in the journal Science. The appeal of a simple Mendelian model had
led to an assumption that eye color "in man is inherited as an alter-
native character" (that is, there were two human eye colors, brown
and blue). The intent of the 1907 study was to test the hypothesis
that human eye colors were inherited according to Mendelian predictions.
The basic approach used was to study eye color in individuals from a
number of families. After examining the data, the authors concluded
that "blue eye-color is recessive to brown" and that "when two recessive
individuals are mated inter se they throw [produce] only the recessive
type." There was also a consideration of "imperfect [blue] owing to
the presence of specks or patches of pigment--the 'gray' or 'hazel'
color." However, the major conclusions of the paper--two primary
eye colors, with brown being dominant over blue--became incorporated
into textbooks and was therefore accepted as correct until relatively
recently. The inadequacy of this simple model becomes obvious upon
examining any large group of humans: you can see all sorts of black,
brown, green and blue eye colors.
Recent studies have led to the conclusion that eye color is a
polygenic trait. There are no true blue, green, or black pigments in
the human eye. Rather, eye color is mostly determined by the amount
of melanin (a single brown pigment that also determines skin and hair
color) present in the iris. A current model, described by the figure
below, proposes that at least two separate genes, each with two
imcompletely dominant alleles, control eye color. Each dominant
allele results in the production of a certain amount of melanin. IF
there is little pigment (no dominant alleles), the eyes appear blue
because of the way light is scattered by the sparse amount of pigment.
The amount of pigment increases progressively with an increase in the
number of dominant alleles. As a result, humans have eyes colors that
may be shades of green (one dominant allele), light brown (two), brown
(three), and dark brown or black (four). This model, along with meiosis,
also explains how two parents of light-colored eyes can have children
with dark eyes.
Figure: This is one possible model for eye color with two different
genes, both with different dominant alleles.
Male AaBb X AaBb Female
hazel hazel
AB Ab aB ab
AB AABB AABb AaBB AaBb
black brown brown hazel
Ab AABb AAbb AaBb Aabb
brown hazel hazel green
aB AaBB AaBb aaBB aaBb
brown hazel hazel green
ab AaBb Aabb aaBb aabb
hazel green green blue
So, there ya are...hope you found it informative! :)
-aj
Sharon Thompson-Schill
>In article <1993Jul26.1...@Synopsys.Com> ka...@synopsys.com (Karen Vahtra) writes:
>> In article Donna Wicks
>>
>> There is no way for two blue-eyed parents to have a brown-eyed
>> baby. The gene possibilities just aren't there. Brooke and Tad
>> could have one bronw-eyed parent that carried a blue-eyed gene,
>> but once a blue-eyed person in conceived the ONLY gene they
>> carry for eye color is recessive.
>>
>>
>>Ah, but the secret (I think) is that there is more than just one
>>gene for eye color. Its more complicated than that! (Read my
>>earlier post on my sister)
>
>This is true! and just for Karinc since we talked about this at
>the get-together, here is the scoop straight from my biology book!
>The second paragraph and final sentence are the kickers:
stuff deleted
>
>Figure: This is one possible model for eye color with two different
>genes, both with different dominant alleles.
>
> Male AaBb X AaBb Female
> hazel hazel
>
> AB Ab aB ab
>
>AB AABB AABb AaBB AaBb
> black brown brown hazel
>
>Ab AABb AAbb AaBb Aabb
> brown hazel hazel green
>
>aB AaBB AaBb aaBB aaBb
> brown hazel hazel green
>
>ab AaBb Aabb aaBb aabb
> hazel green green blue
>
>
>So, there ya are...hope you found it informative! :)
>
OK, but two aabb people could only have aabb kids, even with this
model. I'm not saying blue eyed parents can't have brown eyed kids,
but I don't think this explains it either.
--
Sharon L. Thompson-Schill thom...@psych.Stanford.EDU
AJ
>In article <231pjm$h...@gaia.ucs.orst.edu> a...@cerridwen.ucs.orst.edu (AJ) writes:
>>This is true! and just for Karinc since we talked about this at
>>the get-together, here is the scoop straight from my biology book!
>>The second paragraph and final sentence are the kickers:
>
>stuff deleted
important stuff. ;)
>>Figure: This is one possible model for eye color with two different
^^^^^^^^
>>genes, both with different dominant alleles.
>>
>> Male AaBb X AaBb Female
>> hazel hazel
>>
>> AB Ab aB ab
>>
>>AB AABB AABb AaBB AaBb
>> black brown brown hazel
>>
>>Ab AABb AAbb AaBb Aabb
>> brown hazel hazel green
>>
>>aB AaBB AaBb aaBB aaBb
>> brown hazel hazel green
>>
>>ab AaBb Aabb aaBb aabb
>> hazel green green blue
>
>OK, but two aabb people could only have aabb kids, even with this
>model. I'm not saying blue eyed parents can't have brown eyed kids,
>but I don't think this explains it either.
>Sharon L. Thompson-Schill thom...@psych.Stanford.EDU
You are right sharon...this figure doesn't explain it all, it can't
because it is only a POSSIBLE solution. We simply do not know yet
how many genes are linked to eye color. I think my book gave this
figure, so that students could see an example and get an idea of
what multiples alleles can do to a Mendelian gene chart. I actually
had to do charts with 3 and 4 alleles and it was quite hairy. ;)
I hope I cleared this up now. :)
-aj