BME 80H Lecture Notes - Lecture 7: Punnett Square, Gamete, Online Mendelian Inheritance In Man
11 Jun 2018
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7th lecture
Phenotypes Designation probability
Smooth, Yellow S-Y- 3/4 x 3/4 =
9/16
Smooth, green S-yy 3/4 x 1/4 =
3/16
wrinkled, Yellow ssY- 1/4 x 3/4 =
3/16
wrinkled, green ssyy 1/4 x 1/4 =
1/16
So, these phenotypes are expected at a 9:3:3:1 ratio.
2. A Punnett square showing the gametes and their
possible combinations can also be used. Note that one
allele from each character goes into the gamete (figure
3.10/3.8)
-SsYy x SsYy outcomes again
-SsYy gametes: first separate the S’s so S and s
-S<Y and y = SY and Sy
-s<Y and y = sY and sy
-now make a big Punnett square and you get the results
of fertilization
3. Did Mendel's data fit these expectations?
Mendel's data expected
values
Smooth, Yellow 315 556 (9/16) =
312.75
Smooth, green 108 556 (3/16) =
104.25
wrinkled, Yellow 101 556 (3/16) =
104.25
wrinkled, green 32 556 (1/16) = 34.75
total 556 556
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
So, these phenotypes are expected at a 9:3:3:1 ratio: a punnett square showing the gametes and their possible combinations can also be used. Note that one allele from each character goes into the gamete (figure. Ssyy gametes: first separate the s"s so s and s. Now make a big punnett square and you get the results of fertilization: did mendel"s data fit these expectations? values. Chi squared test (nice description available on p. 56-57/54- *make sure you see the squared* over expected. Degrees of freedom is the number of phenotypic classes. P value = probability that, given the hypothesis is correct, you could see the observed amount of variation (dif from expectation), by chance alone. In this the p value is well over 90% (use the chart) Mendel performed this experiment with all 7 of the characters he studied and found them all to sort independently. Ssyybbaa x ssyybbaa *see hw and extra practice* use product rule.
