Jmenzago Week 2

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Purpose

The purpose of this experiment is to create a true-breeding purple flower on Aipotu by using basic principles of genetics. With the flowers provided (two green, one red, one white), this experiment seeks to determine the relationship between alleles and the flowers' phenotype and use that information to breed a purple flower. This experiment also seeks better understand how mutations can change the phenotype of a flower.

Methods/Results

Methods

Part 1: Identification of alleles

  1. Self-crossed each given flower (Green-1, Green-2, Red, White)
  2. Crossed given flowers with each other in all possible combinations
  3. Self-crossed new colors from step 2 to help identify the genotype of the new phenotypes (Yellow, Blue, Black, Orange, Purple)
  4. Test crossed all flowers with white flower to identify dominant alleles

Part 2: Mutating a pure-breeding flower

  1. Created a pure-breeding red flower through crosses
    1. Self-crossed the given red flower
    2. Crossed red flowers from second generation with each other and repeated with further generations until a homozygous CR flower was created (about 5 rounds)
      1. Tested if flower was homozygous by self-crossing
  2. Mutated the pure-breeding red flower
  3. Analyzed and compared the protein and DNA sequences of the two alleles in the mutant flower using the "Biochemistry" tab in Aipotu

Results

Part 1: Identification of alleles

Table 1
Allele Color
CG Green
CR Red
CB Blue
CY Yellow
Cr White
Table 2
Genotype Phenotype
CGCG Green
CBCY Green
CRCR Red
CBCB Blue
CYCY Yellow
CGCR Black
CRCY Orange
CRCB Purple
CrCr White
C-Cr Color of dominant allele

Experimental results from test crosses showed that there were only five alleles despite there being nine different phenotypes. Self crosses of the starting flowers showed that their genotypes were as follows: Green-1 (CGCG), Green-2 (CBCY), Red (CRCr), White (CrCr). The white allele was deemed recessive because, in all crosses, it was the less prominent phenotype when the red flower was self-crossed. This follows the predictions of Mendelian genetics for crosses between organisms with two alleles that 25% of the offspring will be homozygous dominant, 50% will be heterozygous with the dominant phenotype, and 25% will be homozygous recessive. This was confirmed after crossing all flowers with each other since no cross with white other than a self cross produced a white flower. The given red flower was dtermined to be heterozygous because of the presence of some white flowers in the second generation. The results of the self-cross of Green-2 suggested that some phenotypes are a result of incomplete dominance between alleles Test crosses verified that the black, orange, and purple flowers were also a result of incomplete dominance between two alleles. Test crosses revealed that CR, CB, and CY are equally dominant. CG was shown to be incompletely dominant with CR, but not with CB and CY. A purple flower can be created by crossing a blue and red flower.

Part 2: Mutation of a pure-breeding strain

Protein Sequence

Mutated red flower turned purple

DNA Sequence

DNA sequence

Comparison of the protein sequences showed that the alleles of the mutated purple flower one of the alleles is missing five amino acids. The alleles also have differences in their genetic sequence at positions 60-66 and at position 101. It is unknown which sequences belong to which alleles, but both alleles were originally CR. It is possible that the mutation could have changed the coding sequences for the missing amino acids, resulting in the deletion of those five amino acids or the addition of five amino acids into the sequence. The mutated sequence could be a blue allele, which would result in the purple phenotype since the other allele would still be an unaffected CR. The mutated sequence could also be a new allele that codes for the purple phenotype and is dominant over CR. Any discussion in this post about the results is only speculation. No conclusion can be made about how the mutation resulted in the purple can be made without further biochemical analysis.

Scientific Conclusion

Results suggest that it is not possible to breed a true-breeding purple flower from the given four flowers because the purple phenotype is the result of incomplete dominance between two alleles (CB and CR), not because of an allele that codes for the purple pigment. However, it might be possible to create a true-breeding purple flower by mutating a red flower. Changes in a pure-breeding red flower's DNA and Protein sequences resulted in a purple flower.

Acknowledgements

  • My homework partners for the week were Maya Paniagua, Sahil Patel, and Nicholas Yeo.
    • Everyone worked together to complete Part 1 during class.
    • Maya did most of the work for Part 2 personally and shared her results with the group.
    • Images used for Part 2 results were taken from Maya.
    • I texted Maya for some clarification on what alleles are being compared in Part 2
  • The idea to test cross was given by Kam D. Dahlquist, PhD.
  • Syntax for tables was taken from Christina Dominguez.
  • OpenWetWare:Software/Projects/Editor/Toolbar was used to find the syntax for subscripts and superscripts.
  • This page was used for help with formatting tables
  • Except for what is noted above, this individual journal entry was completed by me and not copied from another source.

Jmenzago (talk) 07:13, 30 January 2020 (PST)

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