Go through the following slides and complete tasks on how to use punnett squares to predict genetic...
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Go through the following slides and complete tasks on how to use punnett squares to predict genetic outcomes of offspring. Read each slide carefully and complete tasks.
Go through the following slides and complete tasks on how to use punnett squares to predict genetic outcomes of offspring. Read each slide carefully and
Go through the following slides and complete tasks on how to
use punnett squares to predict genetic outcomes of offspring. Read
each slide carefully and complete tasks.
Slide 3
Probability can be used to predict the results of genetic
crosses. In other words you can figure out what fraction or
percentage of the offspring will have the trait. To help figure
this out punnett squares are used. A punnett square is a special
chart that is used to show the possible gene combinations in a
cross between two organisms. Before you can create punnett squares
you must understand some of the key terms. Click on the button
below to go to the next slide and view the definitions. Click on
sound icon
Slide 4
Two different genes make up the trait. Click on the colored
word hybrid for the example to appear. The hybrid is circled
because it has an Upper and lower case letter or not the same
throughout. TT Tt tt The genes are the same for the trait. Click on
the blue word purebred for the example to appear. The purebreds are
circled because they have the same letters. TT Tt tt
Slide 5
What the physical appearance of the trait or organism looks
like. Click on the orange word phenotype to view the example. Click
on the sound icon under phenotype for an explanation. This is the
actual gene makeup of the organism. Click on the purple word
genotype for an example. Click on the sound icon under genotype for
an explanation The letters that makeup the trait. The following are
examples. If red roses are dominant over white then the following
could be possible genotypes. T = Red Rose t = White Rose The
possible genotypes are circled TT Tttt The rose could be red or
white, so the phenotype will be red or white. If the genotype is TT
or Tt the rose will be red. If the genotype is tt the rose will be
white.
Slide 6
Write the correct phenotype for the following examples Click on
the gray box and type in what color fur each hamster has if black
fur is dominant over white fur. B Black fur b White fur bb - BB -
Bb - White Fur Black Fur Once you have typed in your answers click
on the answer button below and they will appear.
Slide 7
Write the correct genotype for the following examples Click on
the gray box and type in what the gene makeup would be for each
hamster. Black fur is dominant over white fur. B Black fur b White
fur Purebred Black Fur - White Fur - Hybrid Black Fur - Once you
have typed in your answers click on the answer button below and
they will appear. BB bb Bb
Slide 8
Now that you understand the terms we will come back to the
punnett squares. The first part of creating a punnett square is
choosing the letter that will represent the genes. The only rule I
have is that the letters you choose have a different upper and
lower case. Click on both the good and bad example below. SsSs Same
upper case and lower case AaAa Different upper case and lower
case
Slide 9
Click on the boxes below that would be good letters to choose
to represent the genes that will be used for the punnett square. If
not sure go back to the previous slide and look at the good and bad
examples. Gg Ll KkHh Cc Oo Bb Dd Rr Vv If you have the following
boxes checked then you are ready to move on. Gg Ll Hh Dd Bb Rr Once
you have typed in your answers click on the answer button below and
they will appear.
Slide 10
Now that you know how to pick the letter the next part is to
figure out which is dominant and which is recessive. Remember
dominant is the gene that hides the weaker trait whenever it is
present. The dominant trait is always the capital letter. The
recessive trait is always the lower case letter. Now click the word
example. After you read through the example click on the sound
icon, near the bottom, to listen to an explanation. In pea plants,
round seeds are dominant over wrinkled seeds. Pick a letter to
represent dominant and recessive genes. T = Round Seeds t =
Wrinkled Seeds I chose the letter T to represent the dominant and
recessive genes. Round is dominant so it is the capital T. The
lower case t is wrinkled because it is recessive.
Slide 11
Try these out. Orange tulips are dominant over white tulips.
Pick a letter to represent dominant and recessive. Write the letter
and what it stands for in the gray box below. Click on answer to
see if you are correct. Letters may be different, but make sure
capital and lower case are different. B = Orange Tulips b = White
Tulips Letters may be different, but make sure capital and lower
case are different. H = Brown eyes h = Blue eyes Brown eyes are
dominant over blue eyes in huskies. Pick a letter to represent
dominant and recessive. Write the letter and what it stands for in
the gray box below. Click on answer to see if you are correct
Slide 12
The second part to creating a punnett square is figuring out
the genotypes of the parents. To do this you have to pay close
attention to what the question is asking you to cross. Below is an
example of a question. I underlined the key words that can help you
determine the parents genotype. Click on the sound icon for
explanation. In pea plants, round seeds are dominant over wrinkled
seeds. Predict the genotypes and phenotypes of a cross between two
hybrid round-seeded pea plants. Since they are both hybrid round
that means their letters are different. The first thing you do is
pick your letters, like on previous slide, and then you show the
cross. The cross is shown by the X. R = round r = wrinkled Rr X Rr
Hybrid round Parent 2 Parent 1
Slide 13
Try these!! Write the dominant/recessive letter and then the
cross between the parents in the gray box under the question. Click
on the answer to see if you were right. The letter you chose may be
different, but that will not matter. Look at previous slide if you
are not sure. In mice black fur is dominant over white fur. Predict
the genotype and phenotype of a cross between a purebred black
furred mouse with a purebred white furred mouse. B = Black Fur b =
White Fur BB X bb Purebred Black furPurebred White fur If brown
eyes are dominant over blue eyes in Huskies predict the genotype
and phenotype of a cross beween a hybrid brown eyed husky and a
blue eyed husky. B = Brown eyes b = Blue eyes Bb X bb Hybrid brown
eyedBlue eyes
Slide 14
Now that you have the cross you can create the punnett square.
So far you have picked the letter, labeled the dominant/recessive,
and found the cross. Now we will label and fill in the punnett
square to figure out what possibilities are for the offspring.
Click on the word problem to start. Next click step 1 and then step
2. In mice black fur is dominant over white fur. Predict the
genotype and phenotype of a cross between a purebred black furred
mouse with a purebred white furred mouse. B = Black Fur b = White
Fur BB X bb So far you have completed this. Step 1 Click HereStep 2
Click Here 2 nd take the other parent and write their genotype
letters along the top of the boxes. bb 1 st take one of the parents
letters and write them along the left side of the boxes. I have
circled the BB for parent 1 and moved them over to the box B B
Slide 15
B = Black Fur b = White Fur BB X bb Below is what you have so
far and how to fill in the chart. bb B B Keep clicking on the word
cross until the punnett square is filled in. This shows you how to
fill in a punnett square. Pay close attention. BB BB b b b b Parent
1 Parent 2 Possible genotypes and phenotypes of offspring. Click on
sound icon to hear explanation
Slide 16
See if you can fill in the letters to the punnett square below
correctly. Click on the word answer to see if you are correct. Tt X
tt tt T t Parent 1 Parent 2 tt T t Parent 1 Parent 2 Tt tt
Slide 17
Parents bb B B BB BB b b b b The last part of to creating a
punnett square is finding the genotype and phenotype of the
possible offspring. Below is an example of gene makeup and
appearance of parents and possible offspring. To get the genotype
you look at the letters of the possible offspring. In this case all
of the offspring have Bb, so they are all hybrid. The phenotype is
the color of their fur and in this case all of the offspring will
have black fur, since they are all hybrid and black fur is
dominant. All of their offspring will carry the trait for white
fur, but it will not show through. Click on the sound icon at the
bottom for explanation. In mice black fur is dominant over white
fur. Predict the genotype and phenotype of a cross between a
purebred black furred mouse with a purebred white furred mouse. B =
Black Fur b = White Fur BB X bb Genotype 100% Hybrid Bb Phenotype
100% Black Fur Possible Offspring
Slide 18
Find the genotype and phenotype for the following problem. Now
remember to look at the offspring to determine the genotype and
phenotype. There are 4 boxes so each box stands for 25%. R = round
r = wrinkled Rr X Rr Rr R r Parent 1 Parent 2 RR Rr rr Genotype
Phenotype 25% Purebred RR 50% Hybrid Rr 25% Purebred rr 75% Round
25% Wrinkled
Slide 19
bb B b BB bb b b b b In mice black fur is dominant over white
fur. Predict the genotype and phenotype of a cross between a hybrid
black furred mouse with a purebred white furred mouse. Genotype 50%
Hybrid Bb 50% Purebred bb Phenotype 50% black fur 50% white fur
Below is an exact example of how to set up a punnett square. When
you are writing it on your paper it should be set up like this. The
punnett square is always on the right and the information is always
on the left. I have numbered the steps 1- 4 so you know the order
to solve the problem. Click on each black number in order to see
the explanation. Last click on sound icon near the bottom to hear
explanation. B = Black Fur b = White Fur Bb X bb 4 3 2 1 1.Pick you
letters and make sure the dominat is capital 2. Write the cross of
the parents 3. Create the punnett square. 4. Find the genotype and
phenotype of the offspring using the punnett square.
Slide 20
In roses the color red is dominant over white. Predict the
genotype and phenotype of a cross between two hybrid red roses.
Complete the problem below. Click on the sound icon, near the
bottom, for a quick overview on the steps. Do not click on the
answer until you have completed the entire problem. Remember to
follow the steps from the previous slide. The letter you chose
might be different then mine, but as long as you follow the rule it
doesnt matter. R = Red r = White Rr x Rr Genotype 25% Purebred RR
50% Hybrid Rr 25% Purebred rr Phenotype 75% Red 25% White R r R r
RR Rr rr
Slide 21
Complete the following problem on a sheet of paper. Click on
the sound icon for an explanation. Make sure you use all four steps
to answer the problem. Set up your problem so that it looks like
the punnett on the previous slide. Bring it up to me to correct. If
brown eyes are dominant over blue eyes in huskies predict the
genotype and phenotype of a cross between a hybrid brown eyed and a
purebred blue eyed.