In this topic students need to appreciate the concept of the genome as the complete set of genetic instructions in a cell and that this will therefore determine the full range of proteins that a cell is able to produce.
Sequencing projects have now read the genomes of organisms ranging from microbes to plants to humans. This allows the proteins that will be derived from the genetic code to be predicted. This has also led to the realisation that in more complex organisms there is non-coding DNA and also regulatory proteins. This further complicates the picture of what amino acid sequence and consequently what proteins are or are not produced by a particular cell.
Students need to understand that the genome is regulated by a number of factors. Cells are able to control their metabolic activities by regulating the transcription and translation activities of their genome. Although all cells within an organism carry the same genetic code, they translate only part of it. Both external and internal factors can control gene expression, with epigenetic regulation of transcription being increasingly recognised as an important factor.
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Links and Resources
This animation works as a stand-alone resource that could be downloaded so that students could work through the animation individually, perhaps as a revision activity.
It could also be used for whole class delivery of new material or as revision material.
Even A level students find the structure of DNA quite difficult to put into context. Anything in biology at this scale is quite an abstract idea. This animation helps students to focus down from the scale of the whole organism, through cell structure, into the nucleus and via chromosomes to the structure of DNA.
It is useful to note the way that chromosomes are represented in this animation, which is much better than in many textbook or other resources. A lot of pictures will show chromosomes in a classic ‘X’ shape. This representation is misleading. They are chromatids formed during mitosis. These are an original chromosome and its replicated copy joined at the centromere.
These materials can be used to achieve two learning outcomes.
They contain information sheets which describe the causes and symptoms of a range of genetic disorders. Using these alone will allow students to build up their knowledge of the topic.
There are also stimulus cards that relate to genetic screening and the use of personal biological information. Using these cards can help to develop skills in discussion, debate and consideration of ethical issues.
Students can be split into groups and given opposing points of view to argue before taking a whole class vote. For example, mortgage and loan companies should have access to your genetic records. Give time for each group to develop their argument and then a time limit (say two minutes maximum) for them to deliver their argument to the class. Voting cards are provided so that the class can quickly show their views.
An alternative method could be to divide the class into groups, with them all working on the same issue. Groups are challenged to produce a set of guideline rules that determine when genetic screening technology can be used and how the information is treated.
In this video, from Teachers TV, a group of the UK's leading experts in genetics, medics and bioethics discuss some of the ethical and social issues in modern genomic research.
The video is five and a half minutes long only, but deals with a number of social and ethical issues successfully.
The video could be used to stimulate discussion with students on this issue. Students could watch the video, be given a discussion question and then asked to debate that question in a similar way to the video. It may be possible to video each group and then play these videos in class. This would work well if each group had a slightly different question/issue to debate.
This Catalyst article details how the genome of a plant called Arabidopsis has been unravelled so that this species can act as a model in genetic studies.
The article contains a suitable level of understanding and challenge for A level students as well as some possibilities for undertaking further internet based research.
It would be possible to write some challenging questions linked to this article on sequencing of genomes, as well as directing students to complete some additional research. In this way the article would probably work best as an activity set for homework or independent self directed study.
These materials contain a range of activities where students use real genomic data from the Cancer Genome Project at the Wellcome Trust Sanger Institute to find mutations in a gene associated with pancreatic cancer.
This short animation, from the Wellcome Trust Sanger Institute, is on subcloning, a step in the process of DNA sequencing of the genome of a large organism.
To accompany the animation there is an activity worksheet, where students need to correctly identify the required steps in the subcloning process.
Students or pairs of students could work through the animation and the activity sheet first. It could then be played again as a whole class activity, and each step of the process correctly identified.
The resource does include an answer sheet for teachers for this activity.
In addition to the activity sheet there is also a very good student information sheet which provides a summary of the Human genome project. This would make an excellent revision sheet for students. Questions could be added to this sheet to confirm understanding.
To play the animation, first download the file and save it to your computer, where it will run as a Flash animation.
This is an interesting article for A level biologists to read. It provides context and background to the field of Genomics. There is some useful vocabulary within the article and it gets students into the habitat of reading around the subject area.
It would be a useful article to use as a homework/independent study activity, then have a few questions related to the article as the starter for the next lesson.