Science Student Teachers' Ideas about the 'Gene

Available online at www.sciencedirect.com

Procedia Social and Behavioral Sciences 15 (2011) 2609–2613

WCES-2011

Science Student Teachers’ Ideas about the ‘Gene’ Concept Musa Dikmenli a, Osman Cardak b*, S. Ahmet Kiray b a b

Selcuk University Faculty of Education,Department of Biology Education,42090, Konya,Turkey Selcuk University Faculty of Education,Department of Science Education, 42090, Konya,Turkey

Abstract The purpose of this study is to investigate science student teachers’ ideas about the ‘gene’ concept. This study focuses on the following questions: What kind of descriptions do science student teachers ascribe to gene? What categories can be derived from these descriptions in terms of common features? A total of 140 participating students, who were studying to become primary science teachers at the Ahmet Kelesoglu Faculty of Education of Selcuk University in Turkey, participated in this study. To reveal participating students’ ideas about the ‘gene’ concept they were asked to respond two open questions: (1) What is a gene in your opinion? (2) The participating students were asked to complete a free word association test. In the test, the term ‘gene’ was presented as a stimulus word. Data obtained from the questions were analyzed and the frequencies of the responses were classified in different categories. The results are compared with related literature and recommendations are provided. Keywords: Science student teachers, conceptual frameworks, gene;

1. Introduction The researches have shown that there are a number of misconceptions and learning difficulties about genetics among elementary, secondary, undergraduate and graduate students (Bahar, Johnstone, & Sutcliff, 1999; Bahar, Johnstone, & Hansell, 1999; Dikmenli, 2010; Lewis & Katman, 2004; Lewis, 2000; Marbach-Ad, 2001; Oztas, Ozay, & Oztas, 2003; Pashley, 1994; Venville & Treagust, 1998). It is also indicated that learners have problems in relating concepts and in explaining inheritance in molecular terms (Marbach-Ad & Stavy, 2000; Wood-Robinson, Lewis, & Leach, 2000). In this sense, genetic is thought to be a complicated subject full of abstract conceptual relationships (Flodin, 2009). Lewis (2000), in a study with 482 students, researched about the conceptions by the participants in relation to genetics. The results of this study revealed that there are illusions about the transfer period of genetic knowledge and lack of basic knowledge about the structures related to gen, chromosome and cell. The researcher explained that good understanding of genetics is related to the good understanding of gene as a phenomenon. Saka, Cerrah, Akdeniz et al. (2006), in their study made with secondary students and science student teachers, researched the understanding levels of the participants about the conceptions of gene, DNA and chromosome. In this study, they revealed that the participants had some alternative conceptions about gene, DNA and chromosome. Boujemaa, Pierre, Sabah et al. (2010) investigated university students’ understanding about the

*Osman Cardak. Tel.: +0-3323238220; fax: +0-3323238225. E-mail address: [email protected]

1877–0428 © 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. doi:10.1016/j.sbspro.2011.04.155

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Musa Dikmenli et al. / Procedia Social and Behavioral Sciences 15 (2011) 2609–2613

gene and its functions. The results of this research showed that the gene concepts of the students often reflected Neoclassical model and the Mendelian model. The researches often focused on the difficulties encountered by the students about understanding the concepts in relation to gene, chromosome, DNA and cell division. Despite the efforts applied in line with alternative instruction strategies for the good understanding of the conceptual knowledge about genetic and molecular biology, these difficulties in teaching and learning genetics remains as a problem for students (Banet & Ayuso, 2000; Orcajo & Aznar, 2005; Saka et al., 2006). In this sense, revealing the conceptions by science student teachers about genes is significant in terms of making educational plans for the future. 1.1. Purpose The aim of this study is to investigate science student teachers’ ideas about the “gene” concept. This study focuses on the following questions: What kind of descriptions do science student teachers ascribe to gene? What categories can be derived from these descriptions in terms of common features? 2. Methodology

2.1. Data Collection In order to establish the ideas of the student teachers regarding the “gene” concept, they were asked to answer two open questions: (1) In your opinion, what is a gene? (2) The participating students were asked to complete a free word association test. In the test, the term “gene” was presented as a stimulus as follows: Gene: . . . . . . . . . . . . . . . . . . . . The technique is based on the assumption that providing a stimulus word and asking respondents to freely associate the ideas which come to mind gives relatively unrestricted access to mental representations of the stimulus term (Bahar et al., 1999; Sato & James, 1999). Data obtained from the questions were analyzed and the frequencies of the responses were classified in different categories. The participants were given approximately 20 minutes to write down the answers. As the intent was to benefit from the first purposes to come to the minds of the student teachers, this time was considered sufficient. The open questions given above are the basic data sources for this study. 2.2. Data Analysis Firstly, 140 participant students were asked “What is a gene?”. However, only 138 participants replied this question. For this reason, data analysis was made in four stages on 138 papers. Firstly, the written responses were read in detail to establish the overall level, and it was seen that there was a very wide spectrum of descriptions for gene. Secondly, the “content analysis technique” (Yildirim & Simsek, 2005) was used to separate each description into its components and analyzed for similarities or common factors with other descriptions. Based on the written responses of the participants, the main categories for gene were established. Thirdly, each description was placed in an appropriate category. Lastly, the number of participants (n) and the percentage (%) representing each of the 8 main categories made up of 264 descriptions were calculated. Some participants presented more than one description for gene. As a result of the analysis of the written responses, a total of 264 valid descriptions were identified. Each of them was further examined independently by the researchers and an expert in biology education with an original agreement of 245 for the 264 descriptions. The remaining 19 (7.2%) descriptions were agreed upon following consensus discussions. Data obtained from the free word association test were analyzed. The response words were categorized, using a criterion of semantic relationship and the frequencies of the words in each category were calculated. Many studies have shown this type of data analysis technique provides reliable results (Daskolia, Flogaitis, & Papageorgiou, 2006; Torkar & Bajd, 2006).

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3. Results The responses by the participant students for the question of “What is a gene?” were classified in eight categories. Description of gene by the participants showed variety. The distribution of these descriptions according to categories is shown in Table 1. It should be noted that the responses of many participants fell into more than one category. The gene as a unit of heredity carrying the genetic traits was the dominant category (55.1%). For example, “Gene carries the genetic traits of living creatures. In this sense, it is the most important unit of heredity. All genetic traits of an organism are hidden in the genes” (Student 121). According to the participants representing the second category, gene is a unit providing the continuation of generation (38.4%). For example, “Heredity is a trait transferred from generation to generation. Genes are effective in the transfer of these traits. Genes allow the transference of inherited characteristics from ancestors to offspring” (Student 94). According to the participants representing the third category, gene is a structure consisting of a combination of DNA segments (28.3%). For example, “Gene is the smallest part of DNA having the traits of an individual. Gene is a structure consisting of a combination of DNA segments” (Student 86). According to the participants representing the fourth category, gene is a special unit carrying genetic knowledge on chromosome. For example, “Genes are special units found on chromosomes and carrying genetic knowledge. There are many special parts on chromosomes that carry genetic knowledge” (Student 85). According to the participants representing the fifth category, gene is a unit creating the genetic codes of living creatures (15.9%). For example, “Gene is a genetic code affecting the shape, appearance and behaviour of a living creature. Genes are the units creating the genetic codes of the living creatures” (Student 17). According to the participants representing the sixth category, gene is a structure constituting DNA (13.8%). For example, “Gene is the smallest unit of DNA. Genes come together and create DNA. The smallest building stone constituting DNA is called gene” (Student 105). According to the participants representing the seventh category, gene is a unit determining inherited characteristics (11.6%). For example, “Genes are units determining inborn, inherited characteristics changing from person to person. Genes determine the inherited characteristics of individuals” (Student 109). According to the participants representing the eighth category, gene is a nucleotide sequence (9.4%). For example, “Gene is a nucleotide sequence found in DNA chain. This sequence is specific to the kind” (Student 140). Table 1. Categorization of the science student teachers’ conceptions of gene Categories

n

%

1

The Gene is a unit of heredity carrying the genetic traits

76

55.1

2

Gene is a unit providing the continuation of the generation

53

38.4

3

Gene is a structure consisting of a combination of DNA segments

39

28.3

4

Gene is a special unit carrying genetic knowledge on chromosome

26

18.8

5

Gene is a unit creating the genetic codes of living creatures

22

15.9

6

Gene is a structure constituting DNA

19

13.8

7

Gene is a unit determining inherited characteristics

16

11.6

8

The gene is a nucleotide sequence

13

9.4

Some misconceptions were found in this study during the analysis of the responses given by the participants for the first question. Some of these misconceptions were as follows: -“Inherited materials of living creatures are called gene” (Students 19, 22, 41). -“Chromosomes are formed with the uniting of genes” (Students 60, 69, 73, 132, 133). -“Gene is formed with the uniting of DNAs” (Students 79, 81, 83, 87). -“Gene is the smallest coded protein within the body” (Students 119, 135). Participants’ associations of the term “gene” (a total of 1016 word associations) were arranged into nine categories. A total of 62 (6.1%) of these associations could not be categorized (intelligence, mystery, robot, world, key, space, universe, …). These words appeared once, twice, or three times, and could not be aggregated with the other words. As a result, they were excluded from the results in Table 2. The remaining 78 different associations

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were divided into nine categories. These categories and the response words in each category are listed in Table 2. According to the results, the associations most commonly produced by participants are related to DNA-chromosome (Category 1, f = 203) and heredity (Category 2, f = 201). Other associations were related to protein synthesis (Category 2, f = 114), biotechnology (Category 4, f = 102), phenotype (Category 5, f = 91), medicine (Category 6, f = 73), cell-tissue-organ-organism (Category 7, f = 51) and cell division (Category 8, f = 41) respectively. Table 2. Associations with the term “gene” (categories and answers included in each category, and the cumulative frequency of response words) Total frequency of associations in this category 203

Categories

Associations included in categories and their frequencies

1

DNA - Chromosome

“DNA” (78), “chromosome” (39), “chromatid” (16), “adenine” (13), nucleotide” (13), “guanine” (10), “cytosine” (10), “replication” (8), “thymine” (6), “nucleid acid” (6), “organic base” (4)

2

Heredity

“heredity” (70), “mutation” (17), “recessive gene (16), “generation” (14), “dominant gene” (14), “genotype”, (13), “parent” (10), “allele” (9), offspring (9), “genome” (9), “Mendel” (8), “heterozygote” (7), “homozygote” (5),

201

3

Protein Synthesis

“genetic code” (41), “RNA” (27), “protein synthesis” (14), “enzyme” (10), “uracil” (9), “protein” (5), “transcription” (4), “translation” (4)

114

4

Biotechnology

“GMOs” (16), “stem cell” (13), “gene map” (10), “cloning” (9), “gene transfer” (9), “Dolly” (8), “transplantation” (7), “human genome project” (7), “genetic engineering” (7), “DNA fingerprinting” (6), “biotechnology” (5), “biological weapon” (5)

102

5

Phenotype

“eye color” (25), “phenotype” (21), “hair colour” (16), “hairstyle” (12), “height” (8), “skin colour” (5), “modification” (4)

91

6

Medicine

“disease” (12), “colour blindness” (10), “gene therapy” (9), “haemophilia” (8), “Down syndrome” (8), “health” (7), “diabetes” (7), “cancer” (6), “medicine” (6)

73

7

Cell-Tissue-OrganOrganism

“organism” (19), “cell” (17), “nucleus” (7), “tissue” (4), “organ” (4)

51

8

Cell Division

“crossing-over” (15), “meiosis” (8), “mitosis” (5), “reproduction” (5), “synapsis” (4), “tetrad” (4)

41

9

Others

“biology” (33), “biodiversity” (19), “genetics” (7), “pea” (6), “microscope” (5), “evolution” (4), “life” (4)

78

Total

954

4. Discussion and Conclusions According to the results, while more than half of the participants consider gene as a functional unit (Table 1; Category 1, 2, 4, 5 and 7), others consider it as a structural unit (Table 1; Category 3, 6 and 8). As for science student teachers, although they have scientifically valid conceptions, these conceptions rather correspond to the description of gene in Mendelian and Classical models. According to these models, gene is a particle that provides genetic transmission and an indivisible unit of genetic transmission, recombination, mutation and function. Gene determines a characteristic. Certain characteristics are products of genes settled in well defined locus on the chromosomes (Gericke & Hagberg, 2007). These results demonstrate the fact that the gene conceptions of the science student teachers do not really correspond to the scientific gene description of modern genetics. According to


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modern genetics, gene is a producer of molecules within a development system. Genes have several categories such as genes producing enzymes, regulator genes and genes encoding for RNA molecules (Gericke & Hagberg, 2007; Gerstein, Bruce, Rozowsky et al., 2007). The misconceptions encountered in this study are similar to the misconceptions determined in the previous studies (Boujemaa, Pierre, Sabah et al., 2010; Marbach-Ad, 2001; Saka et al., 2006). This reveals that misconceptions are usually parallel to the explanations suggested by the scientists and philosophers of the previous generation about natural phenomena (Bahar, 2003; Wandersee, Mintzes, & Novak, 1994). Technology based teaching materials and alternative teaching strategies need to be applied in order to provide well understanding of the conceptual knowledge related to genetic and molecular biology. References Bahar, M. (2003). Misconceptions in Biology Education and Conceptual Change Strategies. 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