By completing this task, we will learn about chromosomes, genes, alleles and mutations, as well as some theoretical genetics. It serves as a review of transcription and translation, as well as protein structure. In the final stages, we will also access the Entrez Gene database (ICT requirement 4 on the 4PSOW).
This task is heavily based on the work of others and is credited at the end.
For more excellent case study resources for science, visit the National Center for Case Study Teaching in Science.
Thanks, once again, to Ed Yong for his fantastic NotExactlyRocketScience blog. This video is a must-watch for students, especially those taking HL and the Neurobiology option. Once you’ve seen it, go over to Ed’s blog and read the article “Shedding light on sex and violence in the brain“, which is a really interesting look at the balance between sex and aggression in mouse brains, using this method.
You can see why it is the winner of Nature Methods’ 2010 Method of the Year (click for lots of articles).
Although it is way ahead of the syllabus, there are links to:
- membrane proteins, channels and ions
- depolarisation and hyperpoloarisation of nerves
- transgenics (using viruses as a vector for delivering new genes)
- transcription and translation
- regions of the brain
The world has been all a-twitter with NASA’s news of a new life-form discovery. Putting ‘NASA‘ and ‘life-form‘ together in one sentence seems to have got a lot of people worked up that they have discovered life on other planets and that the invaders are coming, but really it’s all a bit closer to home and rather tamer.
Closer to home, maybe, but still really interesting. These bacteria from Mono Lake in California are able (with a lot of lab-based prodding*) to use arsenic in place of phosphates to build the backbone of their DNA molecules. An interesting link to DNA structure there, and news-worthy in that this species has been able to substitute one fundamental element of living organisms for another, usually more toxic, molecule.
IB Biology curriculum links:
- 3.3 DNA Structure (and AHL 7.1 here)
- 3.1 Chemical Elements and Water
- 2.2 Prokaryotes
- 2.1 Cell Theory (calculate the magnification)
Helpfully, TED has put together a playlist of related talks to put the discovery, and the search for ET, in perspective. Here’s one from Penelope Boston:
Live long and prosper.
*this clause is an edit to clarify.
Lorenzo’s Oil is brilliant for reviewing much of the content of Grade 11, and in particular the Genetics and Biochemistry components of this semester. As you watch, answer the questions on the question sheet.
More ALD resources:
Myelin Project: Augusto Odone’s Website
ALD information page, from the NIH
AccessExcellence questions and ideas for Lorenzo’s Oil
Here is Craig Venter announcing the successful self-replication of a cell with an entirely synthetic genome:
This is one of the biggest news stories of the year, and time will tell what its implications are. It has been extensively covered in the media, and will surely be a part of school ethics discussions for years to come.The full Science paper is online here.
Search for news stories and resources to help you answer these questions:
1. In what ways is this the first synthetic organism?
2. What were the success criteria for this organism?
3. What failsafes were put in place should the bacterium become widespread?
4. What are some of the potential applications of this new technology?
5. What are some of the ethical implications of synthetic biology? Identify stakeholders in the debate and outline their point of view.
DrosophiLab is a brilliant, free and downloadable piece of software that allows students and teachers to edit fruit flies and carry out crosses. The teacher can use the chromosome editor to set up parent flies of any genotype and there are 20 genes and traits represented, on four chromosomes. This allows for simple monohybrid crosses, sex-linkage, gene linkage and many other combinations – so the problems you set can be differentiated by level. There is also a password-protected teacher setting, to restrict students’ access to results tables and chromosome maps (so they have to work it out for themselves!).
Here are our class resources:
Fly files in this folder: http://www.box.net/shared/dy326rb01d
Chi-Calc (Chi-squared calculator, .xlsx)
How to catch and observe Drosophila:
And this is how you tell the sexes apart:
When trying to observe the flies for real, think about the following questions:
- How are you ensuring ethical treatment of the animals?
- How long would it take to determine the phenotypes of the number of flies you have set for your investigations?
- What difficulties do you encounter when observing the flies?
- What are the limitations or sources of error that might affect the reliability of your results?
Why are fruit flies so important in science?
Science loves fruit flies, and there was even a fruit fly Nobel awarded in 1995 for studies in embryonic development. This links neatly to the assessment statements regarding the differentiation of cells through expression of different genes.
Fruit fly cells are relatively easily observed, and Drosophila makes for an ideal model organism for Mendelian genetics as it has a short life cycle, reproduces quickly and is easily phenotyped.
Drosophila buscki from Journal of Endocrinology
Fruit fly graphic and DrosophiLab banner from DrosophiLab
This is a moving clip from the StemCellFoundation, and their channel has lots of decent, informative video clips. Check it out.
Why do otherwise rational, sensible people choose to reject good science in some cases and believe unfounded claims in others?
With apparently eroding trust in government and authority, people are looking to less reliable sources of information – which is particularly dangerous when it comes to health. On the one hand, they believe stories such as ‘Facebook causes cancer‘, or in the unproven alt-meds of homeopathy and vitamin supplements, yet they reject solid scientific evidence with regard to vaccine safety, anti-retroviral drugs or GM crops.
As Michael Specter says in this TED 2010 talk, “We hate BigPharma… and we run from it into the arms of Big Placebo*.”
“The idea that we should not allow science to do its job because we are afraid is really very deadening, and it’s preventing millions of people from prospering.”
From a TOK perspective, how does this talk highlight the clash between emotion and reason in the ways of knowing? (Or as Specter says, “You have the right to your own beliefs- but not your own facts.”)
*The industry in non-proven remedies and vitamin supplements runs to billions of dollars a year.
Start at the Learn.Genetics Firefly overview.
Core (AHL to follow):
Click on the shadowed images for animations and tutorials.
Essential Biology: 3.5 Transcription and Translation (SL/ Core Only)
More basic animations:
Learn.Genetics @ Utah
Transcribe and Translate (good, basic, interactive)
How do fireflies glow? (puts it in context)
University of Nebraska: