3. The four o\'clock plant, Mirabils jalapa, is a classic plant model that produ

Question

3. The four o'clock plant, Mirabils jalapa, is a classic plant model that produces pink or white flowers. Cross- pollin ating a white-flowering plant to a pink-flowering plant produces an offspring with flowers that are tled plants are selfed, the offspring are on average 4 pink, mottled pink and white. When the pink/white mot white, and mottled pink/white. Mirabilis plants also have 3 leaf phenotypes-narrow leaves, wid and leaves of intermediate width. Plants with broad leaves and plants with narrow leaves give rise to plants wi and broad, intermediate, and ya narrow leaved plants in the ith intermediate leaves in the Fi generation F2 generation. You collect data from a random sample of a Mirabilis population and observe the following: 44 plants with wide leaves & pink flowers 23 plants with wide leaves & pink/white mottled flowers 11 plants with wide leaves & white flowers 98 plants with intermediate leaves & pink flowers 35 plants with intermediate leaves & pink/white mottled flowers 47 plants with intermediate leaves & white flowers 78 plants with narrow leaves & pink flowers 31 plants with narrow leaves & pink/white mottled flowers 31 plants with narrow leaves & white flowers Propose a mode of inheritance for each of these traits. Include the number of genes, the alleles, and the relationships among the genes/alleles for both flower color AND leaf morphology. (3 points) a.

Explanation / Answer

a. the mode of inheritance for flower colour is codominance as neither of the phenotypes are recessive.Both the phenotypes are expressed in F1 generation,the mode of inheritance for leaf morphology is incomplete dominance as the population in F2 generation is neither narrow nor wide.The fundamental ratio of genotype is 1:2:1.Here it is 1/4:1/2:1/4.So there are 3 kinds of genotpye present.Total number of population observed is 398 plants.Out of which the number of genes for pink flowers are 220(alleles PP= 220*2=440),for white is 89(alleles=WW=178),for pink/white are 89(alleles=PW=178).The number of genes for narrow leaves are 140(alleles NN=280), for wide are 78(alleles=DD=156), for intermediate 180(alleles=ND=360).

b.allelic frequency for flower colour

There are two types of alleles for flower color P for pink W for white

The total number of alleles for flower colour are 440+178+178=-796

P allele frequency will be number of (pink flowers + 1/2 pink/white flowers)/796= (440+ 89)/796=529/796=0.66

W allele frequency will be number of (white flowers+ pink/white flowers)/796=(178+89)/796=267/796=0.34

C.there are two alleles for leaf morphology N for narrow and D for wide

total number of alleles are 280+156+360=796

N alleles frequency will be number of (Narrow leaf+ 1/2 intermediate)/796=(280+180)/796=460/796=0.58

D alleles frequency will be number of (wide +1/2 intermediate)/796=(156+180)/796=336/796=0.42

d.The hardy-weinberg equation can be written as

P+Q = 1 where the equation is for allelic frequency, that means that sum of allelic frequency should be 1

For flower colour locus

P= P allele frequency=0.66

Q=W allele frequency=00.34

P+Q= 0.66+0.34=1

So this is in hardy weinberg equilibrium.

e. for leaf morphology locus

P= D allele frequency

Q= N allele frequency

P+Q = 0.42+0.58=1

So this is also in hardy weinberg equilibrium .

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