BIO WEEK 7-LAB-Genetic Inheritance

27 Jun BIO WEEK 7-LAB-Genetic Inheritance

Question
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?

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