[nabs-l] punnett squares

Sun Mar 4 22:43:56 UTC 2012

Hi Vejas,
I took regular and advanced placement bio in high school and several
bio courses in college since I was a bio major. I don't think I ever
once made my own Punnett square on the Brailler. It works for some
people, but it is also a big hassle to make up the physical square.
I'll tell you what I did for solving problems like the ones in your
assignment, and you can decide if this method works for you or not.
Say the problem says to cross two heterozygous plants. Instead of
using capital and lowercase letters, since those are less obvious in
Braille, let's use a for the dominant gene and b for the recessive
gene. So on your Braille Note write:
AB+AB
to represent the two heterozygous plants. Then, to figure out each of
the four possible types of offspring from those two heterozygous
plants, pair one letter from each AB and write those pairs down on
your Braille Note on the next line. So, if you pair the first letter
from each AB, you get AA. If you pair the first letter from the first
AB with the second letter of the second AB, you get AB. If you pair
the second letter of the first AB with the first letter of the second
AB, you get BA. And finally, if you pair the second letter of each AB,
you get BB. So the four possible combinations of letters you get from
crossing two AB plants is:
AA or AB or BA or BB
In the plant height example, a tall plant must have at least one A in
it, and a dwarf plant has two B's. So out of your four pairs of
letters, you can count how many have at least one A or how many have
two B's to determine the probabilities of getting a tall or a dwarf
plant, respectively. You will notice that three out of the four have
at least one A in them, and one out of the four has two B's.
For another example, try crossing a homozygous tall plant with a
heterozygous plant. You have
AA+AB
So your four possible pairs of letters are:
AA, AB, AA, AB
This means all of your offspring will be tall because they will have
at least one A in them.

I know this might be really confusing, but I do think once you figure
out how to write it on the Braille Note and practice with it, you'll
be able to do the problems without all the trouble of making up your
own Brailled Punnett square.
If the problem asks you to make a Punnett square, instead of
physically drawing the square, you can write out the probabilities,
i.e. "25% will be TT [two capital T's]; 50% will be Tt [one uppercase
T, one lowercase t] and 25% will be tt [two lowercase t's]. The point
of that is just to show your teacher that you know how to do the
probabilities.
I do think that even if you don't physically draw out your Punnett
squares, it'd be good for you to take a look at some Brailled Punnett
squares so you will see what they look like, which will help you
understand the concepts.
I hope this is helpful and doesn't make your head hurt too much. If it
does, email me offlist and I can try to clarify.
Best,
Arielle

On 3/4/12, josh gregory <joshkart12 at gmail.com> wrote:
> alot more difficult, heck they should make a pc program for it.
>
> On 3/4/12, Chris Nusbaum <dotkid.nusbaum at gmail.com> wrote:
>> Oh yeah! The only problem with that solution, Josh (and BTW, I
>> did the same thing in bio last year, that is, my IA,
>> instructional assistant, Brailled them for me) is when the
>> teacher asks you on an assignment or test or something to
>> actually make the punnet square from scratch.  Then you'd have to
>> use a Brailler.
>>
>> Chris
>>
>> Chris Nusbaum
>> Email and Google Talk/Keychat (on the BrailleNote) ID:
>> dotkid.nusbaum at gmail.com
>> Skype: christpher.nusbaum3 or search for Chris Nusbaum
>>
>> "The real problem of blindness is not the loss of eyesight.  The
>> real problem is the misunderstanding and lack of education that
>> exists.  If a blind person has the proper training and
>> opportunity, blindness can be reduced to a mere physical
>> nuisance."
>> -- Kenneth Jernigan
>>
>>  ----- Original Message -----
>> From: josh gregory <joshkart12 at gmail.com
>> To: National Association of Blind Students mailing list
>> <nabs-l at nfbnet.org
>> Date sent: Mon, 27 Feb 2012 20:13:12 -0500
>> Subject: Re: [nabs-l] punnett squares
>>
>> Or just ask them to braille them out for you, that's what was
>> done for
>> me.  Took a while for me to get it, but I think the teacher said
>> I was
>> one of the few that actually got the concept.  Btw, brings back
>> memories, Ashley.  :)
>>
>> On 2/27/12, Ashley Bramlett <bookwormahb at earthlink.net> wrote:
>>  Hi,
>>  You cannot do punnet squares in a linear form on a braille note.
>> Use a
>>  brailler; yes do them on graph paper or make the  squares
>> tactilly somehow.
>>  I used large print.  But same concepts apply.  Punnet squares
>> are a grid of
>>  squares.  So picture a small table.
>>  I believe they are two rows, two colums as  I recall.  You put
>> two
>>  letters in each square to represent genes.
>>  I really hope I explain the representation right as its been
>> years since bio
>>  for me.
>>  If you bring two of the same letters together, its homozygous.
>> Note the
>>  capital or lowercase letters as I write.
>>  Capitals are dominant and lower case are recessive.
>>  Example:  bb for recessive brown eyes.
>>  Example B B for dominant blue eyes.
>>
>>  If you have different case of letters, its hetro zygous.
>>  You look at the top letter and letter on the side to put the
>> letters in the
>>  square.  For instance a Large P for dominant gene on top and on
>> the side a
>>  small O for recessive gene.  So you write P O in the block.
>>  Quite hard to explain without showing you.  I suggest you ask
>> your teachers
>>  for clarification.
>>
>>  This video might help; maybe if you watch it with a sighted
>> person they can
>>  help you understand it.
>>  http://www.youtube.com/watch?v=J8SQAiVWw_s
>>
>>  Ashley
>>  -----Original Message-----
>>  From: vejas
>>  Sent: Monday, February 27, 2012 7:08 PM
>>  To: nabs-l at nfbnet.org
>>  Subject: [nabs-l] punnett squares
>>
>>  Hi,
>>  I am really, really, really confused with Punnett squares.  So I
>>  have some questions about them.
>>
>>  First, to make them, should I use a Perkins Brailler? I do all
>> my
>>  other science work, as well as for my other subjects except math
>>  homework, on my Braille-Note Apex.  Would a Perkins Brailler be
>>  better?
>>  Also, do you hand-make the grids? I have some graph paper from
>>  math that I might be able to use, but hand-making them might be
>>  easier.
>>  So can you please explain how to make a Punnett? Also, it would
>>  really help if you could additionally tell me how you learned
>>  Punnett squares because I'm really confused.
>>  Thank you for your time.  Attached to this email is a copy of
>> the
>>  questions from the worksheet that I am supposed to do for
>>  homework.  Ignore Problem 10 and any others that you don't have
>>  to solve.
>>  Sincerely,
>>
>>  Vejas
>>
>>
>>
>>
>>
>>
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