Chris Rhodes Week 2

A visual showing all eight possible flower colors

Methods

1. To determine homo- or heterozygous alleles of the parental generation or the original four strands I began by self-crossing each flower. Homozygous crosses would yield only the original color where heterozygous crosses would yield 2 or more colors.
2. To determine a scale of dominance among the parental generation and help uncover the different alleles responsible for each color I inter-crossed all the parental flowers.(See Results: Parental Crosses)
3. To isolate True-breeding flowers for more accurate future dominance tests I self-crossed select progeny of the F1 generation of the Parental crosses. I then self-crossed select progeny from the F2 generation until a pure F3 generation was created for each color(Red, Blue, Yellow). These True-breeding strains were stored in the Greenhouse.(See Results:F1 and F2 Crosses...) Note: Green-1 and White had already been established as true-breeding.
4. To measure a scale of dominance among all the alleles I inter-crossed all the True-breeding color flowers. (See Results: True-breeding Crosses...)
5. To determine the individual alleles that made up each non-true-breeding color (Purple, Orange, Black) I crossed each non-true-breeding color with White. (See Results: Determination of Alleles...)

Results

Parental Crosses

• Cross between Red and Red flowers yields: 20 Red and 7 White
• Cross between Green-1 and Green-1 flowers yields: 23 Green
• Cross between Green-2 and Green-2 flowers yields: 12 Green, 6 Yellow, and 5 Blue
• Cross between White and White flowers yields: 17 White
• Cross between Green-1 and White flower yields: 21 Green
• Cross between Green-2 and White flower yields: 15 Blue and 10 Yellow
  • Both phenotypes were added to Greenhouse as Blue-White and Yellow-White respectively
• Cross between Red and White flower yields: 12 Red and 12 White
• Cross between Green-1 and Red flowers yields: 11 Black and 8 Green
• Cross between Green-2 and Red flowers yields: 10 Blue, 9 Purple, 6 Yellow, 2 Orange

F1 and F2 Crosses to Obtain True-breeding Colors

• Self-cross of Blue-White flower yields: 18 Blue and 10 White
• Self-cross of Blue flower progeny of BW X BW yields: 26 Blue
  • This F3 progeny was added to greenhouse as True-breeding Blue
• Self-cross of Yellow-White flower yields: 16 Yellow and 6 White
• Self-cross of Yellow flower progeny of YW X YW yields: 25 Yellow
  • This F3 progeny was added to the Greenhouse as True-breeding Yellow
• Self-Cross of Red progeny of F1 Cross R X R yields: 27 Red
  • This F3 progeny was added to the Greenhouse as True-breeding Red

True-breeding Crosses to Observe Dominance

• Cross of Green-1 and True-Yellow flowers yields: 26 Green
• Cross of Green-1 and True-Blue flowers yields: 23 Green
• Cross of Green-1 and True-Red flowers yields: 19 Black
• Cross of True-Red and True-Yellow flowers yields: 23 Orange
• Cross of True-Red and True-Blue flowers yields: 28 Purple
• Cross of any True-Color and White flowers yields: 100% True-Color

Determination of Alleles for Black, Orange, and Purple Flowers

• Cross of Black and White flowers yields: 13 Green and 13 Red
• Cross of Orange and White flowers yields: 12 Yellow and 10 Red
• Cross of Purple and White flowers yields: 12 Red and 13 Blue

Conclusion

After reviewing the results from today's experiment a few conclusions can be drawn. Firstly, from the four parent strains of flowers there are eight possible colors of flowers, which are made up of various combinations of five different alleles. These alleles each code for a separate color: green(Cg), red(Cr), blue(Cb), yellow(Cy), or white(Cw). Secondly, the genotypes of the four parental strands are as follows, Green-1:CgCg Green-2:CbCy Red:CrCw and White:CwCw. Thirdly, the scale of dominance of these alleles is as follows: Cw<Cg,Cr,Cb,Cy Cg>Cb,Cy Cg=Cr Cb=Cr,Cy Cy=Cb,Cr CR=Cg,Cy,Cb. The codominance of the various alleles leaves us with the remaining phenotypes and genotypes: Purple(CrCb) Black(CrCg) and Orange(CrCy). Through the use of the classical genetic methods employed in this experiment it is impossible to make a True-breeding purple, orange, or black flower due to their heterozygous genotypes. Future experiments for creating a True-breeding strand of any of those three colors would have to use more advanced methods of analysis such as Biochemistry and Molecular Biology. However, I believe the lab was very successful in laying down the ground work for such future experiments by furthering our understanding of the individual effects that the five alleles have on color and more importantly how the five alleles interact with one another to form new colors. This lab also, helped us gain better insight into the scientific process and experiment design.

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