Brassica rapa Intro

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1 Brassica rapa: An Investigation about genetic and inheritance using brassica plants Erika N. Rosa BIO 181 Dennis Wilson 4/23/2020

2 Table of Contents Abstract 3 Introduction 4 Question & Hypothesis 6 Material 6 Method 7 Result 8 Tables 9 Discussion 9 Future Project 10 Hypothesis 11 Possible Explanation 11 Reference 12

3 Abstract Most plants have similar genetics that pass from generation to generation, but there are also plants that have different genetics. Mendelian genetics help us to know how genetics passes from generation to generation, as well as helping us to determine why some plants end up being tall while others are dwarf. Similarly, it helps us understand why some plants end up presenting genes with dominant or recessive alleles. Being an extensive and complex subject, Mendel's genetics allows us to see how genetics can be similar and varied at the same time and how it can change with the passing of generations. However, Mendelian genetics can be divided into Mendelian Inheritance and Non-Mendelian Inheritance, which are an essential part of growth and help us to understand more about the complexity

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4 Introduction According to Mendel, inheritance refers to inheritance patterns that are characteristic of sexually reproducing organisms. In other words, it also talks about the type of inheritance that can be easily understood as a consequence of a single gene, which normally refers to the transmission of a single gene through a dominant pattern, recessive or attached to chromosome X. At the same time, inheritance has several patterns and mechanisms attached to it, which in turn help us understand more about the inheritance explained by Mendel. According to Mendel's theory "Each Character is determined by a single gel, for which there are only two alleles, one completely dominant and the other completely recessive" (Urry et.al 2017). However, there is an exception by Mendel in which he explains that pod shape character is actually determined by two genes. Another observation is that not all heritable characters are determined so simply, and the relationship between genotype and phenotype is rarely so straightforward. Despite Mendel's observations, he points out that he cannot explain some of the more complicated patterns that he observed in crosses involving other pea characters or other plants species. Which is a factor that highlights why there were no explanations for some of the observations made for the experiment. However, this is not a factor that affects the usefulness of Mendelian genetics, because due to the fact that the basic principles of segregation and independent assortment apply even to more complex inheritance patterns, it is possible to extend Mendelian genetics towards patterns that were nor reported by Mendel. According to the author, “Mendelian genetics is the part of genetics that follows Mendel's devised methodology” (Biology, 2020). It is based on the study of the proportions in which the characteristics of individuals are inherited. In other words, this type of genetics or inheritance has

5 to do with the transmission of hereditary characters from parents to children that usually occurs in organisms during reproduction. In Mendelian genetics "the existence of alleles or genes that may be dominant or recessive and that will determine the physical and functional characteristics of the offspring" is considered (Urry et.al 2011). Due to the fact that in these genetics the existence of dominant or recessive alleles is considered, likewise it is believed that the characters inherited by a single gene deviate from simple Mendelian patterns when the alleles are not completely dominant or recessive. Non-Mendelian inheritance refers to inheritance that is not governed by the hereditary patterns exposed by Mendel, that is, it does not depend on or is determined only by the presence of dominant and recessive genes. The probabilities of the characteristics of the offspring established by Mendel are not observed in this type of inheritance. Codominance, Incomplete dominance, Multiple alleles and Pleiotropy are some of the mechanisms that can be found in Non-Mendelian inheritance. According to the author, “Condolence inheritance means that there is no situation in which one allele prevails over the other, but that both are expressed equally in the individual phenotype, whose phenotype will be shown as a combination of both alleles” (Montagud, 2020). In incomplete dominance, this “type of mechanism implies that the phenotype of an individual is halfway between the phenotypes of the parents” (Montagud, 2020). That is, it is as if it were a mixture between the characteristics presented by the parents. On the other hand, pleiotropy is the “situation that occurs when the same gene codes for more than one characteristic and, therefore, those characteristics are always inherited together” (Montagud, 2020). This help us determine and know more about Mendelian and non-Mendelian inheritance.

6 For this study, observations were made of various plants, including Brassica plants, also known by its scientific name Brassica rapa. According to the author, "This plant is found native from Central Asia (Tibet) to Turkey, Hungary and the Ukraine, although it can be found around the world in temperate and cold regions" (Perdomo, 2004). However, Brassica has a common form of propagation and is through seeds, which do not have special adaptations to dispersal. Its life cycle is quite peculiar and "it is that it blooms in late winter and early spring" (Perdomo 2004). Brassica rapa is used to investigate the genetic mechanism behind the height difference. Question How the genetic mechanism or the characteristic passed down from one generation to the next generation? What type of inheritance patterns will they have? Hypothesis If the F1 plants grow all tall, then the plant will be heterozygotes, which will have a dominant tall gene, and a recessive dwarf gene. Hypothesis II If the F2 plants present a genotype inheritance of the P and the F1 generation, then the F2 generation will produce a 3:1 ratio of tall and dwarf plants. Materials  Styrofoam Container  Diamond-shaped wick  Damp Soil  Pellet Fertilizer (F1 seeds)  F2 Seed (Fertilizer)

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7  Tray  Paper tower (little square)  Water Method 1. Get a Styrofoam container. Add a wick in each corner with half sticking out the bottom. The extends can be about 2 cm out of the hole in the bottom. 2. Fill each square half with damp soil and then add the pellet fertilizer (F1). 3. Fill each square with the damp soil to the top. Make a shallow depression on top of each cell. DO NOT press hard enough to compact the mix. 4. Drop 3-5 seed (osmocote) in each depression square. 5. Cover the seed with a bit of soil, you can also sprinkle enough soil to cover the seed. 6. Water very gently with a piper until water drips from each wick. Be careful not to wash seeds out of the cells 7. If its necessary label the outside of the Styrofoam using a sharpie marker with the seed plants and your class and group. 8. Then place the finished Styrofoam container in a tray. The tray will be lined with a paper tower that is used to soaking in water. This will water the Styrofoam container from the bottom. 9. Observed the plants seed for one week carefully, take note and picture. 10. After one week we counted the number of tall and dwarf F1 plants. Planting F2 seeds: 1. The F2 seed will be collected from the F1 seeds. 2. The F2 seeds were placing using the same procedure as the F1.

8 3. Observed the plant for one week carefully. Take note and picture, so you can have a record of the time. 4. After one week counted the number of tall and dwarf plants. Result For this experiment, data were collected for 7 days, approximately one week, on plant growth. The plants were examined every day to see the growth of each. According to the results, the F1 plants were planted successfully with 100%, according to this, in turn, all the plants surpassed their cut in 1 week. In this way, they all passed the minimum height to be considered tall plants. A table was used to present the data on how many tall and dwarf plants occurred after placing the seeds. The table below shows the results of the F2 plants (see Table 1) Table 1: Number of Tall and Dwarf plants. Class Total Plants 96 Note: It shows the results of the F2 plants one week after being planted correctly. Let us see how many tall plants were produced and how many dwarfs were produced. Table 2: Chi-Square Table Result of the chi-square test Tall Dwarf Observed (o) 68 28 Expected (e) 72 24 Derivation (o-e) 68-72= -4 28-24= 4 Group # Tall Plants # Dwarf Plants 1 13 4 2 10 4 3 11 7 4 13 2 5 9 7 6 12 4 Total 68 28

9 Derivation squared ( d 2 ) -4 x -4= 16 4 x 4= 16 d 2 /e 16 ÷ 72= 0.22 16 ÷ 24= 0.67 X 2 = ∑d 2 / e X 2 = 0.22 + 0.67= 0.89 Note: This table provide the result of the chi-square test, that compared the data we observed with the data we expected to obtain according to an especial hypothesis. Table 3: Punnett square to get the expected result Parent plant Genotype T (tall, dominant) T (tall, dominant) d (dwarf, recessive) Td Td d (dwarf, recessive) Td Td Note: This table show us the expected result for our F1 generation plants . Table 4: Punnett square expectation result F2 Parent plants Genotype T (dominance) d (recessive) T (dominance) TT Td d (recessive) Td dd Note: Punnet square to get the expected result of the F2 generation plants. Discussion My data supports the hypothesis that the F1 generation seed will be heterozygotes, which means that they will inheritance tall gene and recessive dwarf gene from the P and the F1 generation plants. This also means that plants of the F1 generation grow all tall. For starters, I used the punnet square chart to get the results of the research (See Table 3). After one week of planting the F1 seeds, the results of the F1 generation were observed and found to produce only tall plants. Thus, the results confirmed the hypothesis of being correct. Similarly, my data support the hypothesis of the F2 generation, where plants have a genotype of inheritance of P and F1 generation. This results in the F2 generation expressing genes that present the 3: 1 named by Mendel in his experiment that produces tall and dwarf

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10 plants (see Table 1). For the experiment we placed the genotype of the F1 generation in the Punnett square (see Table 3), which gave us the expected ratio of 3: 1. One week after planting the F2 generation, the number of tall and dwarf plants were counted. According to the results, it was found that the F2 generation produced 68 tall plants and 28 dwarf plants. In the next step, the Chi-square test was used to determine if there was a significant or nonsignificant difference in the observations as a result of the F2 generation (see Table 4). The Chi-square test gave us a chi-square value of 0.89 (see Table 2). If we look at the Chi-square distribution table, we can notice that the results of 0.89 fell in the probability category. According to the table the category we fell in gave us the degree of freedom (df) of 1 and a probability of 0.06. These results showed that our probability value of 0.06 is gather than 0.05. This allows us to accept our hypothesis and confirms that the results meet the expectations inheritance mechanism described by Mendel. Future Project Since the hypothesis was supported by the data, some questions for a future project have emerged. First it should be mentioned that genetics can be varied, as is already known. However, there may be other factors that emerge and are responsible for the change in plant growth. Plant growth could be a genetic factor that is affected by different environmental reasons such as water, sun or other environmental variables. Although the genetics of plants is a inheritance passed from generation to generation, there are other variables that affect the genetic inheritance of plants in a different way from what we know today. Possible Hypothesis: If the plants receive a variation of water, then the plants that receive more water will be tall plants, while those who receive less water will be dwarf plants.

11 Possible Explanation: A possible explanation for why some plants grow taller than others, could be due to the fact of how much they receive the planted seeds. A clearer example is that seeds planted deeper will receive more water than seeds planted closer to the surface. This could be a possible answer, to why some plants grow differently and could also explain why genetics in some plants are affected or different. However, the experiment could be carried out in the same way that the planting of the F1 and F2 generation seeds was carried out, with the variation that the seeds would be planted at different levels, allowing some to have more access to water than others. Reference Biología Sur- Genetica Mendeliana [ Southern Biology- Mendelian Genetics]. (2020), Retrieved

12 from: https://www.biologiasur.org/index.php/herencia/genetica-mendeliana Montagud, Nahum Rubio. (2020). Herencia N0-Mendeliana: qué es, ejemplos y mecanismos genéticos. [Non-Mendelian inheritance: what is it, examples and genetic mechanisms]. Retrieved from: https://psicologiaymente.com/miscelanea/herencia-no-mendeliana Perdomo, Francisco Roldón. (2004). Brassica rapa. L. Retrieved from: http://www.conabio.gob.mx/malezasdemexico/brassicaceae/brassica-rapa/fichas/ ficha.htm Urry, Lisa A., Michael L Cain, Steven A. Wasserman, Peter V. Minorsky, and Jane B. Reece. (2017). Campbell Biology: A Custom Edition of the 11 th Edition, BIO 181. New York. 615 pg.

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Brassica rapa Intro

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