PulseProject is an interesting collection of video lectures and podcasts in science. It is aimed at university and IBDP-level (or A-level) students and educators as well as the general (well informed) public. Looking through their list of lectures and videos, there is some leaning towards eugenics and psychology, though there are many that might be of specific interest to IB Biology students:
Genetics & Evolution:
GM Crops and global food security Chris Leaver
Where did you leave your genetic fingerprint? Katharine Wright
Genes and Human History Gil McVean
Descent of the Dinosaurs Chris Jarvis
Music of Life: a new view on nature and nurture Denis Noble
What makes us human? Robin Dunbar
The practice of Eugenics in Estonia Ken Kalling
Saving the Asian Apes (Indonesia link!) Susan Cheyne
Exploring the Ecology of Insects Mike Bonsall
Seven Years to Save the Planet (Climate Change) Bill McGuire
And some bits from our heroes:
Ben Goldacre at Skeptics in the Pub
Marcus du Sautoy on A mathematician’s journey through symmetry
Science + music + YouTube = awesome.
Here are some comedy highlights:
More musical mayhem after the jump…
Students in my class take part in this discussion here.
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As we follow the story of the swine flu Influenza A(H1N1) outbreak on the news and the internet, we start to become overwhelmed with information. In all cases related to health, it is vital that we practice critical thinking and take the time to evaluate our sources of information. The more controversial or the higher the impact of a story, the more likely it is for people to be discussing and disseminating (spreading) misinformation. Misinformation can be due to simple misunderstanding, poor communication of facts or delusion and the intention of misleading others.
In this task, we will look at some of the resources related to the swine flu Influena A(H1N1)outbreak and evaluate their usefulness and reliability. We will see how this outbreak relates to syllabus areas of IB Biology and in particular look at the genetic aspect of the evolution of the pathogen.
Here we go – read and watch these resources and try to pick out information that will help you answer the questions below.
What do I need to know about Swine Flu? from NewScientist
What are the phases of the WHO’s pandemic alert?
The progress of the story (oldest to newest):
Guardian News, 25th April: “Swine flu epidemic kills 16 in Mexico city”
Guardian News, 25th April: “Swine flu symptoms similar to human flu”
PrisonPlanet, 26th April: “Swine flu a beta-test for a bioweapon”
NewScientist.com, 27th April: “Is swine flu a bioterrorist virus?”
Nature.com, 27th April: “Swine flu spreads the globe, genes could contribute to rapid spread”
Wired.com, 29th April: “Swine flu from pigs only, not humans or birds”
Guardian News, 29th April: “Governments must prepare for a pandemic”
Guardian News, 29th April: “Global race to produce swine flu vaccine”
BadScience, 29 April: “Swine flu and hype – a media illness (a risk is still a risk)”
BBC News, 30 April: “WHO raises pandemic alert level”
NewScientist, 2 May: “First genetic analysis of H1N1 shows potecy – and potential weakness”
BadScience, 2 May: “How effective is Tamiflu, really, at stopping the aporkalypse?”
1. Reading the articles from Wired, NewScientist and Nature, can you explain briefly how the new form of swine flu has spread to humans?How does this relate to our Biology syllabus?
2. Which of the sources used above do you consider most reliable? Where should we turn for the most reliable and up-to-date information on health issues? Why?
3. What do you feel is the ethical (most responsible) way to report global diseases in the media? Why?
4. How could irresponsible journalism make the impacts of an outbreak or pandemic more serious? How would you balance the public demand for information with the possibility that giving out too much information might lead to harm?
Take part in at least two of the discussion questions. Make use of the sources provided and show evidence of reading around the subject. Address the guiding questions and build on them with your own ideas, supported by research from reliable sources.Make a minimum of three posts in each of two discussions. Pay attention to netiquette.
Here are some quick reminders of the Biology in action:
The influenza pandemic of 1918 – what might happen now?
Learn.Genetics@Utah awesome resources
And as always, click on the shadowed images in the presentations to be taken to source videos and animations.
Here are all the presentations for the Genetics topics.
More presentations after the jump…
Happy (belated) Christmas!
How do you really reproduce without sexual reproduction? Asexual reproduction, of course. Simple, really… but not for the females of some species.
There are loads of links in this post, so click on them to learn more.
Parthenogenesis can take a range of pathways :
- The egg can be fertilised by a polar body (a ‘leftover’ of egg production), making the chromosome number diploid and triggering embryo development. Here is a simple explanatory animation from amateurmicrography.net.
- Chromosomes in the egg can self-replicate, making up the diploid number and the embryo develops from there.
Other methods include suppression of male genotypes (technically still sexual reproduction?), or eggs cells dividing by meiosis.
The resulting offspring are going to be all the same gender. In some species, the XY system determines gender and parthenogenesis produces all females. In other, the ZW system dictates that they will all be male.
Parthenogenesis is a reproductive strategy that sacrifices the genetic variation (a driving force of evolution) of sexual reproduction for the simple ability to reproduce. Small invertebrates, such as aphids, can use it to produce large numbers of females very quickly.
Larger organisms, such as Komodo dragons (Indonesia link!), have been known to use parthenogenesis in the absence of males, producing an all-male clutch of eggs. It is thought that this might allow them to set up new populations on isolated islands, using just a single female. Here’s a quick video of a Komodo dragon parthenogen hatching:
Parthenogenesis has also been observed in captive sharks – the female had no access to males, yet gave birth to live young (though only one, where the normal litter would be larger). Genetic tests confirmed parthenogenesis, rather than the alternative hypothesis of superfecundation (storing sperm for a long period of time). Read the full paper here, and another on hammerheads here. BBC audio explanation here.
So can it work in us?
Let’s let House MD explain:
In short, no. Not naturally.
Generally, we use mitosis to replace and repair damaged cells and tissues and for growth and development – filling in the gaps with copied cells. Along the way, our cells differentiate to their function and we end up with a body full of specialised cells – each cell’s structure and biochemistry reflect its function.
We don’t use mitosis for reproduction, as it narrows genetic variation – one of the driving forces of evolution. Instead, when sperm and eggs are produced, meiosis is used – producing daughter cells with half a set of chromosomes. During meiosis, crossing over occurs, giving some recombinants – or ‘mixed up’ chromosomes – leading to some varation. The greatest variation comes from the process of sexual reproduction itself – the gametes – sperm and egg – meet in fertilisation, combining their chromosomes to make a new blastocyst, which becomes an embryo, then a fetus and out pops a baby.
All the offspring of organisms that reproduce sexually carry two copies of each chromosome – one from each parent – and each chromosome carries different alleles – ‘versions’ of each gene. This leads to a great deal of variation and this genetic diversity keeps the the population going.
What about uses in technology?
Funny you should ask that…
Induced parthenogenesis is being pursued as a method for obtaining embryonic stem cells. Read this New Scientist article to learn more.
The disgraced Korean scientist Hwang Woo-Suk, who shot to infamy after faking stem cell results, was actually and inadvertently pivotal in the use of parthenogenesis as a method to produce human embryonic stem cell lines:
Normally these parthenogenic embryos die after a few days, yet researchers are able to harvest them for stem cells for research. Ethically, these are considered engineered eggs, rather than human embryos. How do you feel about that?
Questions to think about:
2. How do the XY and ZW gender systems work?
3. How does sexual reproduction lead to genetic variation?
4. What are the costs of parthenogenesis in terms of evolution or resistance to disease?
5. How would the genetic fingerprint of a parthenogen differ from its parent?
6. How would researchers use genetic fingerprinting to determine whether the offspring were parthenogens or were the product of sexual reproduction?
7. What are the ethical considerations of using parthenogenic human ambryonic stem cells?
Chapman et al. Parthenogenesis in a large-bodied requiem shark, the blacktip <i>Carcharhinus limbatus</i>. Journal of Fish Biology, 2008; 73 (6): 1473 DOI: 10.1111/j.1095-8649.2008.02018.x
Chapman et al. Virgin birth in a hammerhead sharkBiol Lett. 2007 August 22; 3(4): 425–427. Published online 2007 May 22. doi: 10.1098/rsbl.2007.0189.