BIO WEEK 7-LAB-Genetic Inheritance

GeneticInheritance
Margaret E. Vorndam,
M.S.Version 42-0061-00-01

LAB REPORTASSISTANT

.gif”>Thisdocumentisnotmeanttobeasubstitute
for
aformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables
that
shouldbeaddressedinaformallabreport.
Theintentistofacilitatestudents’writing
oflab reports by providing
this informationin an editable
filewhich can be sent to an instructor.

Data Table
1: PunnettSquare for F1 Cross – Expected GeneticOutcomes

F1Parent, genes:
(student to
fillin the blanks)

alleles >
alleles v

F1 Parent, g
enes:
__________(student fill
in blank)

Data Table
2: Results of F1 Cross

Observed Phenotypes of F2Progeny

# green plants =

# white plants
=

Total # plants

Petri Dish 1 >

Petri Dish 2 >

Total

.gif”>.gif”>.gif”>

Data
Table 3: Dihybrid Cross in Corn
– Results of P Cross

P = purple,
p = yellow
S = smooth, s =
wrinkled
(student
to fillin all blanks )

Generation

Expected Alleles

Expected Alleles

P >
dominant x recessive

_ppss_

F1Progeny >

Frequency >

Data
Table 3A: PunnettSquare for
F1 Dihybrid Cross

Expected Genotypic Outcomes
(student
to fillin)

Parent
1 F1– can produce
these gametes: (student to
fillin)

Parent2F1 –canproduce
these gametes:
>

ShadedportionaboverepresentstheF2progeny
genotype and phenotype.Student
to fillin.

.gif”>

Data
Table 4: Dihybrid Cross in Corn
– Results of F1 Cross in F2 Progeny

Phenotype of
Progeny

(What they look like – word description)

Genetic Designations possible for this Phenotype

e.g., PPSS

Predicted Allelic
Frequency

(Expected Ratio)

Number of this Phenotype Total Counted:

100 (Observed
Number)

Actual Allelic
Frequency

(Observed
Ratio)*

e.g., Yellow, wrinkled

ppss

* Actual
Allelic Frequency (Observed Ratio)
= Number of this PhenotypeTotal
Counted ¸ 100 kernels total counted

Data Table 5: ?2Goodness of Fit Test
for F Phenotypic Results from F Corn Cross
2 1

Phenotype
Description
of
F2Progeny from
Table 4

Observed
Number from Table 4

Observed
Ratio from Table 4

Expected Ratio from
Table 4

* Expected Number, calculated

** [Observed
No. – Exp. No.]2
÷ Expected No.

e.g., Yellow, wrinkled

? Sum of column =

c2,Chi-square value
***
>

* Expected
Number, calculated
= ? Sum of Observed
Number x Expected Ratiofor that
phenotype
** = (Observed
number – Expected number, calculated)
square
÷ Expected
Number, calculated
*** c2,Chi-squarevalue=?Sumof(Observednumber–Expectednumber,calculated)
squared ÷ Expected
Number, calculated

Data Table 6: Summarizationofc2 Good Fit Results
for F Corn Cross
1

c2 value from Table
5 =

Value at 3 Degrees of Freedom that is closest to
c2
value =

What is the Fit Probability at the top of the column in which the value was
found?

What is the % of probability that the observed
results match the expected
results?
(MultiplyFit Probability
by 100)

Reading at the top
of the Table, this Fit Probability indicates that the expected results
hypothesis is a

Good Fit Poor Fit

Circle the correct choice above

Exercise
1: F1 Hybrid Cross

A. Expectedphenotypicratioofgreentowhiteprogeny: CalculationofExpectedRatio
(Frequency) = = Total Number of (Color) Seedlings ÷ Total
of All Seedlings.

B. If 320 F2offspring
resulted from this F1cross, how
many would be green?

White?

DISCUSSION

A. Did the results support or refute
the hypothesis? Explain.

B. How
similar are the observed to
the expected results from the PunnettSquare?

C. If the results are not
similar, how might the differencebe explained?

D. WillamonohybridF1crossincornyieldthesameratioofexpectedphenotype
inprogenyas
for the tobacco seedlings? Why or why
not?

E. Ifavailable,
compareyourF2seedlingdatatothoseofyourclassmates.Aretheoutcomeratios the same? Why might using a larger
number of seedlings to determine
this outcome be wise?

Exercise
2: Dihybrid GeneticCrosses
PROCEDURE

1. Basedonwhatyoucanconcludeaboutitsgeneticmakeupwhentoldthatthecornplant parentcross(P)picturedinFigure2isbetweenacompletelydominantplantandacompletely recessive plant,

a. Constructandrecordahypothesisaboutwhatthegeneticmakeupandthefrequencies oftheallelesfortheF1 progenyplantsinthedihybridcrossofcornwillbe.Recordyour
hypothesis here:

b. IftheseF1 progenyaremated,whatwillbetheresultingallelic
frequencyfortheF2
progeny? Record
this hypothesis here:

RESULTS

A. Whatarethetwohypotheses
thatyoumadeabouttheallelicfrequenciesofprogenyproduced by
the crosses:

P x P?

F1x F1?

B. Based
on
what you
know about phenotypes and Figure 2, for
the
P
generation, what is
the
corn plant genotype on
each
cob containing the
P
corn kernels?
One is completely dominant, so its genotype is

One
is completely recessive,
so its genotype is .

C. WoulditmakeadifferenceintheoutcomeofthiscrossifthegenotypeofoneparentisPPss and the other is ppSS?

D. Fromthephenotype
ofthekernelsoneachPgeneration cobwhatwouldthepredicted
genotype of any F1plant
be?

E. Giventhe2nequationpredicthowmanydifferentgeneticoutcomeswillbepossiblefroman
F1cross
resultingin the F2generationin
a dihybrid corn cross.

F. IfaF2corncobresulting
fromthisF1crosscontained
563seeds,howmanyoftheseeds
would you expect to look like
the F1parent?

QUESTIONS

A. How
well do the predicted results match the actual results in Table 4?

B. Based
onthePunnettSquarepredictions,canastatementbemadeastowhetheryour hypotheses
are supported or rejected? Which and why?

C. DihybridF1 crossesresultinapredictableF2 progenyphenotypicfrequencythatholdstrue
universally. Based on the
Expected outcome, what is it?

D. If your
results are not as expected why
might there be differences?

E. Whatapplicationsmightthistypeofgeneticinvestigationhave?Howmighttheinformation
be applied medically?

Exercise
3: Chi-square and Hypothesis Testing
QUESTIONS

A. Whatcanbeconcluded
aboutyourprediction
ofexpectedF2 progenyphenotypicoutcome from
the F1cross? Was it close to the observed
outcome?

1

B. Howmightthec2testforfitnessbeusedinotherways?TryitonthetobaccoseedlingF
cross, for
instance.

C. Inatypicalcrosswhereaparentwithacompletelydominanttraitismatedwithaparent
exhibiting acompletelyrecessivetrait,whatistheexpectedgenotypicoutcomeandallelic frequency
for the F1progeny?

Give an example.

D. InatypicalcrosswherehybridF1parentsaremated,whatistheexpectedgenotypicoutcome and allelic frequency of the F2progeny?

Give an example.

E. FortheF2 progenyproducedfromatypicalF1 hybridmating,howmanytotallyrecessive individuals would be produced if
the progeny total
populationis six offspring?

What if the progeny populationwas
20?

50?

1,000?

F. Excluding
factorssuchassex-linkedgenes,incompletedominance
orepistasis,etc.,willthe above cross
results vary if differentorganisms
are used, such as dogs or tulips? Why or why
not?

G.
Howwillfactorssuchassex-linked genes,incompletedominance,orepistasis,
etc.,affectthe
expected outcomes that
were
investigatedabove?