This focus idea is explored through:
Contrasting student and scientific views
Student everyday experiences
Students commonly bring ideas of genetics from ‘folklore’: ways in which families describe what and how certain characteristics are inherited. Their ideas can be further confused via popular reporting of genetics in the media.
Examples of these conceptions include:
- that any observable variation between organisms of the same species is solely due to environmental factors
- that not all living things contain genetic information
- that a gene is not a real thing
- that genes that carry the genetic material are only found in the blood or only found in the brain or only found in the reproductive system
- that a person will only carry genes for characteristics they display (such as tongue rolling) and not for characteristics that they do not display (such as red hair)
- that acquired changes (e.g. muscle development) can be passed onto offspring
- that genetic inheritance involves an averaging of the genes from both parents (e.g. dark skin and white skin leads to brown skin) so each of a child’s characteristics is somewhere in between those of the parents.
Research: Driver, Squires, Rushworth & Wood-Robinson (1994), Lewis, Leach & Wood-Robinson (2000)
Widespread confusion exists among students between the concept of inherited changes in populations that take place over large periods of time (generations) and that of non inherited changes in individual organisms that take place over the period of the organism‘s lifetime.
Research: Lewis, Leach & Wood-Robinson (2000)
Scientific view
Genetic material, including genes and DNA, controls the development, maintenance and reproduction of organisms.
Genetic information is passed from generation to generation through inherited units of chemical information (in most cases, genes). Organisms produce other similar organisms through sexual reproduction, which allows the line of genetic material to be maintained and generations to be linked. Through reproduction, organisms in a species maintain a ‘bank’ of genetic information which links individual members and successive generations.
Variations in characteristics, such as skin or hair colour, result from the population containing a range of genetic information for the characteristic. Characteristics that are not seen may be carried in genetic information (recessive) by individuals and can be passed on. This means that offspring may display characteristics different from their parents. The characteristic that is observed may be controlled by a number of genes. There are a large number of possible combinations of genes from both parents. The characteristics of the offspring need not be an intermediate of the two parents.
Organisms possess genetic material that contains information for the development of characteristics. This material passes from one generation to the next through reproduction.
All plants and animals are made up of cells where the genetic material can be found in the form of genes and chromosomes (usually in the nucleus).
Research: Lewis, Leach & Wood-Robinson (1999)
Changes that take place in an organism over its lifetime (for example, darkening of human skin due to exposure to sunlight) normally have no effect on the organism‘s genetic makeup and because of this will not be passed on to the organism’s offspring. Changes to an organism that are a result of or result in genetic mutation alter the genetic makeup of an organism and can be passed on to the next generation.
Research: Wood-Robinson (1994)
Mutations are changes in an organism‘s genetic information that potentially affect the current functioning of that genetic information.
Critical teaching ideas
- Genetic material provides the information that allows living things to function.
- Genetic information can be passed on from generation to generation. The passing on of this genetic information will be different in asexual and sexual reproduction and cloning. Variations within this information are more likely in sexual reproduction.
- Changes in genetic information (for example, from mutation) can give rise to variation in characteristics and can be passed on through the generations.
Explore the relationships between ideas about genetic information ideas in the
Concept Development Maps – (Variation in Inherited Characteristics, Cell Functions, DNA and Inherited Characteristics, Natural Selection, Cells and Organs).
Students need to realise that genetic material is found in all living things and it carries information that directs the organism's functioning.
By studying reproduction students should develop an understanding that genetic information is passed from one generation to another via organised chemical structures.
Students need to study examples of changes in genetic information that can arise due to mutation. They should also study the impact of acquired changes on organisms and develop an understanding that these changes are not inherited because they are not created by genetic changes.
For organisms to survive it is important that the information needed for survival is passed on through the generations. If a population has sufficient variation within its genetic information, it is more likely to respond successfully to changes in the environment. Mutations can assist by increasing the variation.
Teaching activities
Collect evidence/data for analysis
Students could be given a group of organisms and asked to track the variations that have occurred in that species. For example, for tiger snakes in Australia, one species has developed into 6 individual species:
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Notechis scutatus (Common Tiger Snake)
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Notechis ater ater (Krefft's Tiger Snake)
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Notechis ater niger ( Peninsula Tiger Snake)
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Notechis ater occidentalis (Western Tiger Snake)
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Notechis ater serventyi (Chappell Island Tiger Snake)
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Notechis ater humphreysi (Tasmanian and King Island Tiger Snakes).
Clarify and consolidate ideas for/by communication to others
The students could then comment on how this variation has enhanced the chances of survival in different environments and contributed to changes in a pool of genetic information.
Students could create their own ‘David Attenborough’ type documentary. They could pick an organism to investigate; local examples might be frogs, dogs, kangaroos, fungi or birds. They could also choose to create a documentary about plants including those that have been genetically modified for food. For ideas on how to carry out this type of activity the students could watch videos such as David Attenborough documentaries.
Promote reflection on and clarification of existing ideas
Another activity might be for the students to design high tech genetic identity cards; for this students may need to research the possible ethical and human rights considerations of collecting this personal information. They would also need to consider whether certain drugs would be able to alter genetic information and how this information would be recorded on the identity cards.
Students might also produce identity kits which would include family information, photographs and family background. This could lead to discussion on who would have access to these and why they would need that access.
Collect evidence/data for analysis
Students should use a variety of visual images to collect and describe data about the changes that can occur within and between organisms. They would need to research using books, journals and the internet, and then analyse their research to produce their findings.
Promote reflection on and clarification of existing ideas
Students might also discuss the causes and sources of mutations as well as other sources of variation (such as recombination). They will also need to discuss and analyse the ethical aspects of genetics and how these impact on humans.
Open discussion by a shared experience
Ethical issues and dilemmas associated with genetics can elicit student need to know and provide excellent routes into student engagement.
A useful resource to explore the role of the sickle cell gene in natural selection is: