a step by step method. what is a punnett square? a punnett square is a diagram used to try to...
TRANSCRIPT
![Page 1: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/1.jpg)
A step by step method
![Page 2: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/2.jpg)
What is a punnett square?A punnett square is a diagram used to try to
predict the outcome of a cross between 2 parents.
It does not tell us what will happen, but it does tell us the likelihood that something will happen.
![Page 3: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/3.jpg)
Monohybrid crossesThese are crosses that only look at a
single traitEx: hair color, eye color, albinismEx: What are the chances that my
baby will have brown eyes?
![Page 4: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/4.jpg)
Step 1Draw a box and divide it into 4 squares.
These squares represent the possible offspring
![Page 5: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/5.jpg)
Step 2Determine the
genotypes of the parents. ____x_____
Place the alleles for the genotypes of the parents on the sides and top of the square.
As a general rule, we put the dad on the top and the mom on the side.
R R
r
r
![Page 6: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/6.jpg)
Step 3Now you multiply
the sides with the top to get the genotype of the 4 offspring boxes.
r
r
R R
Rr Rr
Rr Rr
![Page 7: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/7.jpg)
Step 4Now you can see
what the genotypes of the offspring would be.
In this case there is a 100% chance of the offspring being heterozygous for the trait because all 4 out of 4 boxes are capital, lower case.
r
r
R R
Rr Rr
Rr Rr
![Page 8: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/8.jpg)
RatiosGenotypic
Ask your self: How many homozygous dominants? How many heterozygous? How many homozygous recessives?
PhenotypicAsk yourself:
How many dominant phenotypes? How many recessive phenotypes?
![Page 9: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/9.jpg)
Let’s PracticeHomozygous (HO) or Heterozygous (HE)
AA ____Bb ____Cc ____Dd ____
Ee ____ff ____GG ____ HH ____
HO
HE
HE
HE HO
HO
HO
HE
![Page 10: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/10.jpg)
Determine Phenotype
Purple flowers are dominant to white flowers
PP _____________Pp _____________pp _____________
Brown eyes are dominant to blue eyes
BB ____________Bb ____________bb ____________
Purple
Purple
White
Brown
Blue
Brown
![Page 11: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/11.jpg)
For each phenotype list the genotype
Straight hair is dominant to curly.
____________ straight____________ straight____________ curly
Pointed heads are dominant to round heads.
____________ pointed____________ pointed____________ round
SS
Ss
ss
PP
Pp
pp
![Page 12: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/12.jpg)
Problem #1Draw punnett squareStep 1
In pea plants, spherical seeds (S) are dominant to dented seeds (s). In a genetic cross of two plants that are heterozygous for the seed shape trait, what fraction of the offspring should have spherical seeds?
![Page 13: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/13.jpg)
Problem #1Determine the genotype of parents, and place alleles on punnett square
Step 2
In pea plants, spherical seeds (S) are dominant to dented seeds (s). In a genetic cross of two plants that are heterozygous for the seed shape trait, what fraction of the offspring should have spherical seeds?
________ x ________ Ss Ss
S s
S
s
![Page 14: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/14.jpg)
Problem #1Multiply sides to get possible offspring Step 3
In pea plants, spherical seeds (S) are dominant to dented seeds (s). In a genetic cross of two plants that are heterozygous for the seed shape trait, what fraction of the offspring should have spherical seeds?
________ x ________ Ss Ss
S s
S
s Ss
SsSS
ss
![Page 15: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/15.jpg)
Problem #1Step 4 Interpret the possible offspringStep 1 Draw punnett square
SpongeBob SquarePants recently met SpongeSusie Roundpants at a dance. SpongeBob is heterozygous for his square shape, but SpongeSusie is round (recessive). What is the ratio of round to square pants?
________ x ________ Rr rr
R r
r
r Rr
rrRr
rr
2:2
Step 3 MultiplyStep 2 Determine Parent genotypes
![Page 16: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/16.jpg)
Dihybrid crossesDihybrid crosses are punnett squares used to
predict the probability of an offspring having 2 traits at the same time.
Ex: What are the chances of my baby having brown eyes AND blond hair.
![Page 17: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/17.jpg)
Step 1Draw a box and
divide it into 16 squares.
![Page 18: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/18.jpg)
Step 2Determine the
genotypes of the parents
Ex: cross two pea plants that are heterozygous for yellow peas and round peas.
Yellow is dominant to green and round is dominant to wrinkled.
YyRr x YyRr
![Page 19: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/19.jpg)
Step 3Determine all of the
possible gamete combinations for each parent by using the F.O.I.L. or Gremlin method
FOIL= first, outside, inside last
Ex: YyRr First- YROutside- YrInside- yRLast- yr
YyRr
Gremlin
![Page 20: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/20.jpg)
Step 4Write all of the
possible combinations of alleles on the sides and top of the punnett square.YRYryRyr
YR
YR
Yr
Yr
yR
yR
yr
yr
![Page 21: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/21.jpg)
Step 5
YR
YR
Yr
Yr
yR
yR
yr
yr
Do the cross Remember to keep
all of one letter together and all of the 2nd letter together.
YYRR YYRr YyRR YyRr
YYRr YYrr YyRr Yyrr
YyRR YyRr yyRR yyRr
YyRr Yyrr yyRr yyrr
![Page 22: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/22.jpg)
Step 6Go through the
results and determine what the phenotype of each offspring would be
YR
YR
Yr
Yr yR
yr
yrYYRR
Yellow round
YYRr
Yellow, round
YYRr
Yellow, round
YYrr
Yellow,wrinkled
YyRR
Yellow, round
YyRr
Yellow, round
Yyrr
Yellow, wrinkled
YyRr
Yellow, round
YyRR
Yellow, round
YyRr
Yellow, round
yyRR
Green, round
yyRr
Green, round
Yyrr
Green, wrinkled
yyRr
Green, round
Yyrr
Yellow, wrinkled
YyRr
Yellow, round
yR
![Page 23: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/23.jpg)
Step 7Figure out the
phenotypic ratio or answer whatever question they ask you.9:3:3:1
Example: what are the chances of having a yellow and wrinkled pea?3/16
YR
YR
Yr
Yr yR
yr
yrYYRR
Yellow round
YYRr
Yellow, round
YYRr
Yellow, round
YYrr
Yellow,wrinkled
YyRR
Yellow, round
YyRr
Yellow, round
Yyrr
Yellow, wrinkled
YyRr
Yellow, round
YyRR
Yellow, round
YyRr
Yellow, round
yyRR
Green, round
yyRr
Green, round
Yyrr
Green, wrinkled
yyRr
Green, round
Yyrr
Yellow, wrinkled
YyRr
Yellow, round
yR
![Page 24: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/24.jpg)
Let’s PracticeDetermine the gametes for the following
cross: heterozygous tall plant with heterozygous yellow seeds with another of the same genes. Tall and yellow are dominant
F.O.I.LTtYy
First- Outside- Inside- Last-
Gremlin
TtYyTY
TytY
ty
![Page 25: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/25.jpg)
Problem #4
What percentage of offspring could be chestnut and pacing?
Step 1 Draw punnett squareIn horses, black is dependent
upon a dominant gene (B), and chestnut color upon its recessive allele (b).
The trotting gait is due to a dominant allele, (T), the pacing gait to its recessive allele, (t).
Cross a homozygous black, homozygous trotting horse with a chestnut, pacing horse.
________ x ________ BBTT bbtt
BT
bt
Bb
BbBb
Bb
0%
Step 3 and 4 Determine gametes and place on squareStep 2 Determine genotypesStep 5 Fill in the squareStep 6 Analyze resultsStep 7 Answer question(s)
BT BT BT
btbt
bt
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
BbTt chestnut, trotting
![Page 26: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/26.jpg)
Problem #5
NNBB: NnBb: nnbb:
Step 1 Draw punnett squareSuppose the alpha male and
alpha female of a wolf pack are black with blue eyes and normal colored with brown eyes, respectively. Assume further that normal coat color (N) is dominant to black (n) and brown eyes (B) are dominant to blue (b). The female is also heterozygous for both traits.
What fraction of the offspring could have the following genotypes?
________ x ________ nnbb NnBb
nb
nb
Bb
BbBb
Bb
0/16
Step 3 and 4 Determine gametes and place on squareStep 2 Determine genotypesStep 5 Fill in the squareStep 6 Analyze resultsStep 7 Answer question(s)
nb nb nb
nBN
bN
B
NnBb normal, brown
Nnbb normal,
blue
nnBb black, brown
NnBb normal, brown
NnBb normal, brown
NnBb normal, brown
Nnbb normal,
blue
Nnbb normal,
blue
Nnbb normal,
blue
nnBb black, brown
nnBb black, brown
nnBb black, brown
nnbb
black, blue
nnbb
black, blue
nnbb
black, blue
nnbb
black, blue
4/16 4/16
![Page 27: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/27.jpg)
Problem #6Step 1 Draw punnett square
Carrion beetles lay their eggs in dead animals and then bury them in the ground until they hatch. Assume that the preference for fresh meat (F) is dominant to the preference for rotted meat and that the tendency to bury the meat shallow (S) is dominant to the tendency to bury the meat deep. Suppose a female and male carrion beetle heterozygous both traits mate. What is the phenotypic ratio?
________ x ________ FfSs FfSs
FS
fs
Bb
BbBb
Bb
Step 3 and 4 Determine gametes and place on squareStep 2 Determine genotypesStep 5 Fill in the square
Fs fS fs
fSF
sF
S
FFSS fresh,
shallow
FFSs fresh,
shallow
FfSs fresh,
shallow
FfSS fresh,
shallow
FFSs fresh,
shallow
FFss fresh, deep
FfSS fresh,
shallow
![Page 28: A step by step method. What is a punnett square? A punnett square is a diagram used to try to predict the outcome of a cross between 2 parents. It does](https://reader035.vdocument.in/reader035/viewer/2022081504/56649dbd5503460f94aaf580/html5/thumbnails/28.jpg)
Problem #6
Fresh/shallow: fresh/deep: rotted/shallow: rotted/deep
Carrion beetles lay their eggs in dead animals and then bury them in the ground until they hatch. Assume that the preference for fresh meat (F) is dominant to the preference for rotted meat and that the tendency to bury the meat shallow (S) is dominant to the tendency to bury the meat deep. Suppose a female and male carrion beetle heterozygous both traits mate. What is the phenotypic ratio?
________ x ________ FfSs FfSs
FS
fs
Bb
BbBb
Bb
9:3:3:1
Step 5 Fill in the squareStep 6 Analyze resultsStep 7 Answer question(s)
Fs fS fs
fSF
sF
S
FFSS fresh,
shallow
FFSs fresh,
shallow
FfSS fresh,
shallow
FfSs fresh,
shallow
FfSS fresh,
shallow
FFSs fresh,
shallow
FFss fresh, deep
Ffss fresh, deep
ffSS rotted,
shallow
ffSs rotted,
shallow
Ffss fresh, deep
ffSs rotted,
shallow
ffss rotted, deep
FfSS fresh,
shallow
FfSS fresh,
shallow
FfSS fresh,
shallow