An explanation of the choice and sequencing of the genetics topics

Below I explain my choice and sequencing of topics in the genetics course outline that I developed as part of my study: a week by week course breakdown. In the explanation, I also include the ideas from literature and from my own experiences of teaching the genetics course, ideas that students have been seen to bring to class about genetic phenomena.

Week 1: An exploration of students’ prior knowledge of genetics. Basic structures in genetics

(nucleotides, DNA, genes, chromosomes)

In week one, I explore students’ knowledge of genetics and I teach about the basic structures of genetics. My first course outline did not have these aspects. This was because as explained earlier, at the time that I did my first course outline, I was given a list of topics that I was expected to teach. I did not question or change anything in the original list of the topics because as someone coming straight from a high school classroom I saw the list as something that could not be questioned or changed. Even after observing that there was nothing about DNA, chromosomes and genes on the list, I did not find out if this content was being covered elsewhere. I just assumed that the molecular model content was being covered in the courses that preceded the genetics course. Then, the literature review that I did in 2009 in preparation for the Life Sciences subject advisors’ workshop (see section 1.3.4) awakened me as it was reporting that students of genetics lack an understanding of the structures of genetic phenomena; DNA, genes, chromosomes (e.g. Duncan & Tseng,

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2011; Lewis & Wood-Robinson, 2000). Therefore, in 2010, after the 2009 workshop, I decided that it was important to find out what the students knew about the structures of genetics at the beginning of the course so as to know where to start from and how fast to go. I prepared a number of exercises to establish the students’ knowledge of the nature of genetic information and how that information is interpreted. Students’ responses to these exercises revealed that the students knew very little about the nature of genetic information, and gene expression. I therefore considered these observations in my planning of the new genetics course and made a decision that in the new course, I would start the genetics course by finding out the knowledge of genetics that students bring to class.

From my experience as a teacher educator of genetics at Wits University’s School of Education, I have realized that every year, there is a sizeable number of students who enrol for the genetics course who have never done genetics before. This observation made me decide that after finding out what students know about genetics, I will start the course with the topic basic structures of genetics: DNA, chromosome, gene, RNA and genetic information and the relationships among them (The molecular model). I was however worried that there is no mention anywhere in the Life Sciences syllabus or in the Life Sciences course outline, or in my previous genetics course outline of the teaching of the cell (structure and function) and protein synthesis. I wondered whether there was an assumption by those who had unpacked the syllabus for Life Sciences that students should, by the time they finish Matric (High School), have a good knowledge of the concept of a cell, its structure and functions and hence, there was no need of teaching these concepts at university level or was it just an oversight. Many students of genetics that I have taught in the past could not draw or label correctly, a diagram of an animal or a plant cell. They also could not explain how an organism ends up with different types of cells in its body. Students lack the knowledge of the cell which is fundamental to the understanding of genetics. This observation highlighted the need to incorporate this topic in my teaching. I therefore decided that I would use the first practical session to teach about cell structure and function. Each practical session is three periods long. This is enough time to teach about cells and for students to do practical activities based on the cell. So although the topic cell structure and function does not appear in my course outline, I cover this content in the first practical.

The omission of protein synthesis in the syllabus was also a cause for concern for me. Firstly, because it is a section of the South African grade 12 syllabus and hence our students as teachers of tomorrow should know this content. Secondly, research shows that one common misunderstanding that is exhibited by students is the belief that genes are directly

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responsible for the traits (Lewis & Kattmann, 2004; Lewis, Leach, & Wood-Robinson, 2000b; Marbach & Stavy, 2000). Students do not understand that the products of genes are proteins and in a few cases RNA and that it is the interaction of proteins that determine an organism’s phenotype (the traits). Therefore, if students are not formally taught about the mechanism of protein synthesis, they will lack the knowledge of this important link. Due to time constraints, I could not include this concept in my new course outline. I therefore discussed this with a colleague who is responsible for teaching the chemical background to Life Sciences in the Science Division. This background includes nucleic acids. I asked her to include the content from gene to protein so that when I take over from her to teach the genetics course, the students would have the knowledge about the gene expression model.

In my course outline, the teaching of the molecular model is followed by the meiotic model in week two.

Week 2: Meiosis

When teaching meiosis, I will look at the following:  purposes of meiosis

 process of meiosis  products of meiosis

When I teach about meiosis, I make explicit the link between the behaviour of chromosomes and the purposes and products of meiosis. I decided to teach meiosis after the basic structures of genetics because meiosis has to do with the transmission of genes and chromosomes which I would have covered in the teaching of basic structures of genetics. I decided to teach meiosis before teaching transmission genetics because meiosis is a mechanism which gives meaning to problem solving (Stewart, Hafner, & Dale, 1990) as it explains the inheritance patterns evident in traits in our everyday life.

At the time of developing my genetics course outline, mitosis was not being taught in the genetics course or anywhere in our Life Sciences programme. This omission was again a cause for concern as mitosis is an important process that students need to know. There is unity in function and purposes of different processes of genetics and for students to gain a robust understanding of genetic phenomena; they need to be able to make the necessary links between the various processes and structures. A good example is the link between meiosis, mitosis and sexual reproduction in the transfer of genetic information. Leaving out mitosis creates a content gap that will make it difficult for students to understand transfer of genetic material from cell to cell within an organism. I therefore brought to the attention of my colleagues in the science division, the absence of mitosis in the Life Sciences programme

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and the teaching and learning difficulties that it creates. It was then agreed that in future both the topics cell structure and function and mitosis would be incorporated into the First Year biology course.

My reflection: This was the first time I had identified important omissions in our curriculum

and to bring them to the attention of my Life Sciences colleagues. This was because previously, I had focused on teaching the topics that had been given to me only without giving much thought to the coherence of these topics to other sections in the Life Sciences programme. I had also looked at the list of topics as something that could not be questioned. I never took time to look at the whole Life Sciences syllabus and evaluate how the topics link to other topics in the syllabus. Through developing the genetics course outline, I was able to not only identify problematic issues in our curriculum but to also think of ways of overcoming those problems to help improve the teaching and learning of genetics. My own professional development was implicitly taking place through the process of designing a new course outline. By identifying problematic issues within the Life Sciences curriculum and bringing those to the attention of my colleagues impacted the way my colleagues also viewed their roles and responsibilities. One senior colleague suggested that we needed to conduct regular meetings as Life Sciences lecturers in which we would discuss issues pertaining to our Life Sciences curriculum. The suggestion was agreed upon. We began our monthly meetings in 2013 which culminated in the revision of our Life Sciences curriculum.

After meiosis I teach about mutations.

Week 3: Mutations

There are two types of mutations namely gene and chromosome mutations. Chromosome mutations are also referred to as chromosome aberrations. I decided that the best stage to teach about mutations is after having looked at genes, chromosomes and meiosis as knowledge of these concepts is necessary if students are to understand what mutations are, how they occur and how they cause genetic disorders. The focus would be on mutations that cause genetic disorders in humans as these directly affect us as human beings. Under the topic mutations, I would include a look at genetic disorders and genetic

counselling and testing.

Week 4, 5 and 6: The inheritance model: Mendel, monohybrid inheritance, genetic

diagrams, Punnett squares, co-dominance, incomplete dominance, multiple alleles, sex determination and sex-linkage

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The next topic in my course outline is the inheritance model. I need three weeks to teach about this model. The inheritance model involves a look at how genetic information is transmitted from parents to offspring and at inheritance patterns. An inheritance pattern defines the basic relationship between genotypes and phenotypes (Collins & Stewart, 1989). The content includes solving problems of inheritance. Typical genetics problems can be grouped into four classes. These four classes are simple dominance, co-dominance, multiple alleles and sex linkage problems. These classes of problems differ in the number of variations. Therefore, under the topic of inheritance, I teach about:

 Simple dominance  Co-dominance  Multiple alleles

 Sex determination and sex linkage.

I also teach the concept of incomplete or partial dominance. This I regard as a fifth class of genetics problems. The main focus in this section is interpretation and solving of genetics problems in the five classes of genetics problems. At the end of the course, students must be able to explain the patterns they see in given data using the above inheritance pattern models. Inheritance patterns models explain how genes interact to produce variations that are observed in the traits. To teach the inheritance model, I first look at the history of Mendel who is regarded as the Father of genetics. When looking at Mendel, I also want my students to appreciate some aspects of the nature of science. So we will look at how people failed to understand Mendel’s findings during Mendel’s time and how scientists now understand and can explain them. I believe the History of Science is an important inclusion in that it helps students understand that science is a human activity. Using Mendel’s experiments, I introduce the terminology of genetics followed by simple monohybrid inheritance problems. When I introduce monohybrid inheritance, I also introduce the use of genetic diagrams and

Punnett squares when solving genetic problems. Research has shown that students are

able to use genetic diagrams and Punnett squares to correctly solve genetic problems without understanding the concepts behind each step that they take in solving the problems (M. U. Smith & Kindfield, 1999). I will therefore make explicit in my teaching the links between inheritance, meiosis, independent assortment, and random fertilisation as represented in genetic diagrams and Punnett squares.

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Note that I have put down dihybrid inheritance as a topic to be taught in week seven. What this means is that I will require a seventh week to be added to the duration of the genetics course if I am to teach dihybrid inheritance.