Category Archives: Uncategorized
Conservation of Biodiversity
This one is for the HL students in Option G: Ecology and Conservation.
Essential Biology: G4 Conservation of Biodiversity
Interesting article:
“Should Pandas be left to go extinct?” from the Guardian.
Proteins (AHL & C1)
Although we are learning this in the Chemistry of Life unit, it is actually part of the SL Option C and HL additional material, so look for the book chapters in the right place!
Essential Biology 7.5 & C1: Proteins
Proteins:
Life Cycle of a Protein from Sumanas
Making polypeptides from John Kyrk
Check that you know the different levels of protein structure, including the roles of hydrogen bonds and disulfide bridges. Think about how the properties of the R-groups on amino acids cause the protein to fold up in a set configuration.
FoldIt!
Make sure you can give examples of fibrous and globular proteins and that you can name some examples of uses of proteins that are not structural or related to the plasma membrane.
And don’t forget to play FoldIt – the brilliant protein puzzle that helps medicine!
The Greenhouse Effect
Here is the class presentation – shadowed images are links. I’ve included the slides from G3 on the ozone layer. Make sure you understand that the greenhouse effect itself is a natural phenomenon, enhanced by human activity. Be sure also to distinguish between the greenhouse gases in the troposphere and ozone layer – they are in different positions, with different functions.
Essential Biology 5.2 and G3: The Greenhouse Effect and Impacts of Humans on Ecosystems.
Click4Biology:The Greenhouse Effect
More decent resources from Cutting Edge
Use these CO2 data to plot trends and annual cycles with a spreadhseet.
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Carbohydrates, Lipids and Proteins
Here’s the class presentation – click the shadowed images for animations.
Essential Biology: Carbohydrates, Lipids and Proteins (core)
Essential Biology: Proteins (7,5 / C1)
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For more information on condensation and hydrolysis reactions:
Simple explanation by Terry Brown
Collection of examples from North Harris College
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Carbohydrates:
Explanation and animation from National Louis University
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Lipids:
Structures of Fats from HHMI
Lipids (and condensation animation) from National Louis University
The revision notes from Click4Biology are here.
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Impacts of Humans on Ecosystems
For Option G: Ecology and Conservation. Because we’re learning this concurrently with the Ecology and Evolution core topic, the Essential Biology document has been rolled into one: Essential Biology 5.2 & G3 – Greenhouse Effect and Impacts of Humans on Ecosystems.
The presentation on The Greenhouse Effect will follow soon.
The Cove
Winner of the Sundance 2009 audience award:
Find out more about the cove here:
If you get the chance to see it, think about how it links with the Ecology and Conservation unit:
What is happening in terms of bioaccumulation and biomagnification of toxins?
Is this approach to the dolphin populations sustainable?
ToK Link:
The actions portrayed in the movie are considered by many to be unethical but by those committing them to be a necessary part of life. Think about what determines one’s set of personal ethics – what parts of our own lives might be considered unethical by others? Are there actions we carry out which are unethical but which we choose not to think about because it is uncomfortable or inconvenient to do so?
International Mindedness:
How does this method of farming compare to intensive cattle and poultry farming in other industrialised countries?
Here’s a short clip of an intensively-farmed chicken’s life:
And you and find out more about it on Channel 4’s Hugh’s Chicken Run page.
PulseProject.org – Lectures and Podcasts in Science
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
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Ecology:
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
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And some bits from our heroes:
Ben Goldacre at Skeptics in the Pub
Marcus du Sautoy on A mathematician’s journey through symmetry
Ruchard Wiseman (the Quirkology guy) on the luck factor
Hybrid Hearts: Stem Cell Transplants 2.0
“Can we use stem cells to make a new heart/eye/lung/liver etc?”
This is the predictable and perennial question that comes up from at least one student when we are looking at stem cells, genetic engineering, cell differentiation and transplanting. Until now, the answer has (perhaps in an oversimplified way) been ‘no’.
We can use stem cell transplants to treat lymphoma. Recently a young woman had a trachea transplant based on stem cell technology. Skin grafts from a patient’s own cultured cells are also possible, as are stem cell-based bladders. However, these are all rather simple technologies.
To treat lymphoma, bone marrow cells are replaced, and are all the same. The trachea transplant was a pre-existing trachea simply coated in the patient’s stem cells to prevent immune rejection. Skin transplants are basically sheets of epidermis that cover a wound, yet do not have the intricate functions of original skin: temperature regulation, secretion, senses. The bladder is a bag.
The challenge with using stem cells to transplant a more complex organ, such as a heart, is that it is not a simple sheet made of one type of cell. It is complex 3D structure, with a range of cells performing specific tasks within the organ. These cells have differentiated to perform their functions: cardiomyocytes (beating cells), vascular endothelial cells (smooth internal surfaces) and smooth muscle cells (blood vessel walls).
How can we get the stem cells to become the right type of cell, in the right position?
The answer to this question could be the key to opening up new doors in the search for viable transplantable organs in medicine, and bears much in common with the trachea case. It also marks a return to form for the NewScientist YouTube channel, who have this short clip of the new hearts in action:
A full article to accompany the footage is here.
In a nutshell:
Decellularised pig heart: the scaffold (NewScientist)
1. Find a suitable transplant organ, such as a pig’s heart.
2. Strip of all cells and DNA, using a detergent. Only the collagen ‘scaffold’ remains, as in the image of the decellularised heart to the right.
3. Coat the scaffold with the recipient’s stem cells.
4. Ensure that the blood supply is adequate and will provide the right signals for differentiation.
What is amazing in this case is how the cells ‘knew’ what specialised cells to become. The leader of the research group, Dr. Doris Taylor, puts it down to the mechanical stimulus of the pressure of the blood in the vessels and chambers and chemical signals from growth factors and peptides that remained on the stripped heart structure.
They even went as far as replacing a healthy rat’s heart with one of these new hybrid hearts. The rat survived for the trial, but she says they need to focus on producing more muscular hearts in order to ensure long-term survival of transplant recipients.
Food for thought:
Read the whole article and some of the links within it. Discuss these questions:
1. What are the potential uses for this kind of transplant technology?
2. What are the current limitations of this method and how might they be overcome?
3. What are the ethical issues related to using hybrid (pig-human) organs in medical transplants? How would you feel if you were the patient?
4. Who are the various stakeholders in this technology and what are their viewpoints?
Useful Sources:
Dr Doris Taylor’s research page from the University of Minnesota
NewScientist Article: Hybrid hearts could solve transplant problem
BioAlive stem cells links and resources
Can stem cells repair a damaged heart? from the NIH
Research reveals how stem cells build a heart, from Harvard news.
Amgen: Hi-tech Cancer Video Resources
This resource was first posted on Wired.com and looks great – if you have the bandwidth to load and play it. Amgen is a for-profit US-based biotechnology company that are working on pharmaceuticals to combat cancer and other illnesses. With this resource, including 15 videos, they show how they are working to combat tumour angiogenesis – the critical stage in cancer development which often leads to complications and mortality.
As the tumour grows, it requires a blood supply and angiogenesis provides this – by growing new blood vessels. The risk now is metastasis – some of the tumour could pass into the new blood vessels and be carried around the body, where they might reinvade and grow in a new location. Metastasis accounts for the majority of deaths related to cancer.
To enter their flashy angiogenesis website, click here.
Or for a sneaky peaky:
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There are also some good angiogenesis animations on YouTube, which might load more easily:
A longer explanation from Envita healthcare:
And for loads of great information, the National Cancer Institute has a series of slides with information, and a powerpoint presentation free to download.
i-Biology 