Topic 12

Limit to the following. * Chromosomes are mainly made of deoxyribonucleic acid (DNA), sections of which are referred to as genes. * DNA undergoes replication as part of cell division to pass on the genes to new cells. * Children inherit genes from their parents via the sex cells (gametes), with 50% from the mother and 50% from the father. Many millions of different combinations of these genes from the same parents are possible. * Human characteristics (or phenotype) are determined by their genes (the genotype). * Some characteristics are expressed developmentally by genes (for example, eye colour, gender), others also require an environmental switch (for example, height, VO2max). Note: Students are not expected to know the structure of DNA, the mechanism of replication, or the details of meiosis

Limit to the following. * Genes code for the production of proteins, which are responsible for the development of an individual. * Genes can be switched on or switched off depending on internal or external factors, so that characteristics influencing athletic performance can change during a person’s lifetime. * Multiple genes determine the measurable heritable characteristics for each individual so it is highly unlikely that a single or even a few genetic elements are associated with superior athletic performance. Note: Students are not expected to know the mechanisms of transcription or regulation of gene expression.

Characteristics that are influenced by genetics include height, muscle fibre type, anaerobic threshold, lung capacity and flexibility. Environmental factors that also influence performance include physical training, nutrition, technological aids and climate. Training maximizes the likelihood of obtaining a performance level with a genetically controlled ceiling. Elite athletes can be distinguished from less wellperforming athletes with respect to both inherited (genetic) characteristics and training histories. It is presently not possible to ascertain the relative contribution of genetics or training to elite sporting performance, and this contribution is likely to differ for different sports. TOK: Both environmental and genetic factors influence sporting performance. When two areas of knowledge are linked, how can we decide which has more relevance? Aim 8: Studies on twins have provided much scientific knowledge about the “nature versus nurture” debate, but are such studies morally acceptable?

Consider: * the identification of life-threatening conditions such as risk of sudden cardiac death, connective tissue disorder * the potential to predict susceptibility to injury and so reduce risk/improve safety for an individual athlete * ethical implications of involuntary exclusion from, or discrimination in, one or more sports * ethical implications of discrimination beyond sport, for example, in employment * the possibility of gene doping in the future to improve athletic performance. Link to option B: Psychology of sports: Talent identification and development