Investigation of the Mendelian Genetics with Wisconsin Fast Plants - Lab Report Example

Abstract

Purple stem Wilson fast plants consist of anthocyanin which is a purple pigment found in several plants that include Wisconsin fast plant used in the experiment. The pigment can be observed best at 4-7 days. This could be observed at the plant hypocotyls and stems under the leaf tips and cotyledons. The main objective of the experiment was to investigate Mendelian Genetics with Wisconsin Fast Plants. In this case, the planted progeny seed (F2) from the self-cross phenotypes was observed then a statistical analysis was carried out to determine how well the progeny seedlings ratios conformed to the prediction for a Mendelian dihybrid cross.

Introduction

The experiment was based on the general procedure as that of monohybrid activity. In this case, the P1 and p2 plants are homozygous for two traits that include one dominant and one recessive. Four phenotypes were considered in this investigation of dihybrid genetics that include following; Firstly, non-purple entails no expression of purple anthocyanin pigment in the plants (anthocyanins) and the genotype of this mutant that is recessive is anl/anl. Secondly, Purple entails a pigment referred to as purple anthocyanin visible on the hypocotyls. This trait is known to be wild-type (dominant). The genotype is ANL/ANL Thirdly, the yellow Green; in this case, the homozygous (yr/yr) produces a plant that is light green than the normal green fast plant. Fourthly, the normal green genotype is wild type (dominant) for yellow-green and it is known as YGR. Purple stem Wilson fast plants consist of anthocyanin which is a purple pigment found in several plants that include Wisconsin fast plant used in the experiment (Williams, 1986). The pigment can be observed best at 4-7 days. This could be observed at the plant hypocotyls and stems under the leaf tips and cotyledons. It is well known that the single gene (anl) regulates whether anthocyanin will be expressed or not. The (and/anl) homozygous form is seen to be completely suppressed. In this case, the plant will appear bright green (non-purple). The yellow-green gene (ygr) determines whether the leaves will be either green or yellow-green in color. The leaves will appear pale (yellow-green in color for recessive (ygr/ygr). But for YGR/YGR genotype the leaves will appear green and in this case, this genotype is the wild type. The test that is normally applied to show how well the observed ratios fit the expected statistical ratios is referred to as the chi-square test. In this case, the observed number deviations are calculated from the expected numbers into a single numerical value referred to as x2

The experiment hypothesis

There is no statistically significant deviation of the progeny seedlings (F2) ratios from the prediction for a Mendelian dihybrid cross.

Methods

During the experiment seeds were planted then the phenotype was observed in P1, P2, and F1 plants. The plants were grown under fluorescence lights until they flowered. After this stage self –cross (F1XF1) was undertaken. The plants were grown until the seeds and pods had matured and died. At this stage, the plants were harvested and the progeny seeds (F2) from the self-cross were planted. The progeny seed (F2) from the self-cross phenotypes was observed then a statistical analysis was carried out to determine how well the progeny seedlings ratios conformed to the prediction for a Mendelian dihybrid cross.

Results

Expected ratio

Expected number of plants

Purple stem with green leaves

9

29.25

Purple stem with yellow green leaves

3

9.75

Non purple stem with green leaves

3

9.75

Non purple stem with yellow green leaves

1

3.25

Table 1.The phenotype ratio expected in the F2 generation based on the hypothesis

Phenotype

Observed number of plants

Observed ratios

Purple stem with green leaves

17

8

Purple stem with yellow green leaves

10

5

Non purple stem with green leaves

19

9.5

Non purple stem with yellow green leaves

7

3.5

Table 1.the phenotype number of plants observed in the F2 generation

Phenotype

1

2

3

4

Observed value(O)

16

10

19

7

Expected value

29.25

9.75

9.75

3.25

Deviation(d)=O-E

13.25

0.25

9.25

3.75

Deviation squared

175.56

0.625

85.563

14.063

d2/e

6.002

0.0064

8.776

4.327

Table 3. Summary of the statistics used in the testing of the hypothesis

The Chi-square value was determined by first adding together all the d2/e values and it was 19.1114

Then the degree of freedom was determined which was 3 (4-1). This was used to get the probability value in the provided table and it was 4.1 %( 0.04). The Probability value is observed to be less than 0.05 or 5%. Therefore we reject the null hypothesis.

Discussion

According to the results of the experiment and hypothesis testing to investigate Mendelian Genetics with Wisconsin Fast Plants, we had to reject the null hypothesis. This implies that there is statist tically significant deviation of the progeny seedlings (F2) ratios from the prediction for a Mendelian dihybrid cross. We, therefore, conclude that the progeny seedlings ratios do not conform to the prediction for a Mendelian dihybrid cross. However, the probability value (4.1%) was close to 5 %. The deviation was considered to be significant and this means that the results don’t support the hypothesis hence was rejected. Since the probability value was close to 5%, it is appropriate for scientists to run more tests to ascertain if the results were repeatable. In relation to the outcome of the results, the cliché similar to two peas is not appropriate genetics. This is because the two peas (in a pod) phenotypic potential might be different as ANL/YGR VS anl/ygr. Also smooth and yellow vs. wrinkled. Hence the genetic differences can be seen in F2 seeds without growing them.