CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF STUDY
Over the years, right from the second half of the 20th century, genetics progressively became an essential field of biology also feeding controversial ethical, social and economical debates. The multiplicity and availability of products and applications of genetic technology (GMOs, DNA fingerprinting, screening of genetic diseases, gene therapy, cloning, … ) are more and more daily present, requiring us a high level of scientific literacy and understanding of these issues for a citizenship control (Dawson & Schibeci, 2003; Marbach-Ad, 2001).
According to Banet & Ayuso, (2003) stated that genetics is also one of the most difficult subjects in the biology curricula at the secondary school. The term “gene” was introduced by Wilhelm L. Johannsen in 1909. This central concept in genetics was initially defined as an entity of calculations to account for the transmission of hereditary traits. It became a material entity firstly as a part of chromosome (Morgan, 2001) and then, with the development of molecular biology, as a segment of DNA. More recently, three types of genes were defined related to their functions: genes coding for proteins, genes specifying the untranslated RNA (tRNA, RNAs … ) and the regulatory genes. The more recent conceptions of gene have never totally replaced earlier conceptions: Multiple scientific conceptions of the gene are coexisting (Morange, 2004). Several authors tried to categorize them. Griffiths distinguished two different conceptions of the gene: The molecular gene is “the molecular process underlying the capacity to express a particular polypeptide product”, and the evolutionary gene is “a theoretical entity with a role in a particular, atomistic approach to the selection of phenotypic traits” (Griffiths & Neumann, 2009). Later, Griffiths and Stotz outlined three conceptions of the gene: instrumental, nominal, and postgenomic:
“The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide range of fields grounded in welldefined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit”. (Griffiths & Stotz, 2006).
Gericke and Hagberg (2007) defined five different historical models of gene function: the Mendelian model, the classical model, the biochemical-classical model, the neoclassical model and the modern model. (1) In the Mendelian model, the gene is a hypothetical construct and its main purpose is to explain genetic transmission, no connection was however made to a material unit in the cell. (2) In the classical model, the gene is a particle, an indivisible unit of genetic transmission, recombination, mutation and function. The gene determines a characteristic. Definite characteristics were the product of genes, which were located at well-defined loci on the chromosomes. (3) In the biochemical-classical model, the gene is a particle of transmission, function, mutation and recombination. The gene produces a substance that determines a characteristic. Tatum proposed in 2001 the one-gene-one-enzyme hypothesis for genetic function. (4) In the neoclassical model, the gene is a materiel unit consisting of a DNAsegment. In this model, structure and function coincide and the gene codes for the production of a polypeptide. The neoclassical view of the gene peaked at about 2000 and stated that the gene (cistron) is a contiguous stretch of DNA that is transcribed as one unit into messenger RNA, coding for a single polypeptide. (5) The modern model of gene function considers the gene as a hypothetical construct with a diverse material base consisting of DNA segments that take part in a developmental process. The gene is a producer of molecules in a developmental system. There are a number of categories of genes such as enzyme-producing genes, genes producing structural (nonsoluble) proteins, regulatory genes, and genes coding for RNA-molecules. No direct entities representing environmental aspects are present in this model.
On the other hand there have variation as regards the level of understanding of gene among secondary school student; this could be as a result of the various phases in gene. Genetics is the study of how characteristics are inherited and how variations occur within a species (Kilgour, 1987). It covers the following aspects: variations, mitosis and meiosis, monohybrid crosses, sex determination, sex linked characteristics, co-dominance and mutation (CDC, 2000).
1.2 STATEMENT OF PROBLEM
In Nigeria today, it has become evident that most biology student always fail genetics during internal and external examination (WAEC and NECO); some skip genetics when studying. The reason behind their actions could be that most of the students do not find genetics interesting. It could also be as a result of the effect of teaching and learning methods used by most biology teachers. It could be lack of instructional materials. Secondly there have been series of study on gene but not even a single study has been carried out on senior secondary school students understanding of gene in Nigeria.
1.3 AIM AND OBJECTIVES OF STUDY
The main aim of the research work is to examine senior secondary school students understanding of gene. The specific objectives of the study are:
1. to determine the extent to which gene is taught in secondary schools in Nigeria
2. to determine the difference in senior secondary school students understanding of gene
3. to examine whether gender have significant effect on the level of understanding of gene among senior secondary school students in Nigeria
4. to investigate on the factors affecting senior secondary school students understanding of gene
5. to determine the effect of teaching methods on student understanding of gene
6. to proffer solution to the above problem
1.4 RESEARCH QUESTIONS
The study came up with research questions so as to ascertain the above stated objectives of the study. The research questions for the study are:
1. To what extent is gene taught in secondary schools in Nigeria?
2. What is the difference in senior secondary school students understanding of gene?
3. Does gender have significant effect on the level of understanding of gene among senior secondary school students in Nigeria?
4. What are the factors affecting senior secondary school students understanding of gene?
5. What is the effect of teaching method on students understanding of gene?
1.5 SIGNIFICANCE OF STUDY
The study on senior secondary school students understanding of gene is a very important one in the sense that the study will reveal information about gene. The study will shows the difference in the level of understanding of gene among senior secondary school students in Nigeria. The study will serve as a repository of information to other researchers that desire to carry out similar research on the above topic. Finally the study will contribute to the body of existing literature and knowledge in this field of study and provide a basis for further research
1.6 SCOPE OF STUDY
The study on senior secondary school students understanding of gene will be limited to the senior secondary school student from ss2 to ss3 only.
1.7 LIMITATION OF STUDY
Financial constraint– Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
Time constraint– The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work
1.8 DEFINITION OF TERMS
Gene: gene is a sequence of DNA or RNA that codes for a molecule that has a function. During gene expression, the DNA is first copied into RNA
DNA: Deoxyribonucleic acid is a thread-like chain of nucleotides carrying the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses
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