Category Archives: 04 Genetics

Genetic Engineering & Biotechnology Update

Here is the updated presentation for 4.4 Genetic Engineering and Biotechnology. There are some new slides and clearer explanations, as well as a new visual identity. It should also be downloadable as a pptx file.

For many more resources go to the page for 4.4 Genetic Engineering and Biotechnology.

Are we ready for neo-evolution?

An entertaining and informative TED talk by medical ethicist Harvey Fineberg on the future of human evolution and the ethics surrounding the decisions that we may soon be able to make regarding our children and our health. With strong links to the Human Genome Project, evolution, ethics, genetic engineering, stem cells and TOK, this is a great video to watch and stimulate discussion and thought in the Genetics unit.

What do you think?

DrosophiLab – Genetics Simulator

Drosophila buscki
Drosophila buscki

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:

Protocol sheets: DrosophiLab HL, DrosophiLab SL (pdf)

Fly files in this folder: http://www.box.net/shared/dy326rb01d

Chi-Calc (Chi-squared calculator, .xlsx)

How to catch and observe Drosophila:

Catch Your Own Drosophila, from Access Excellence (lots of resources there)

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.

Fly!
Fly!

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.

There is a biography of fruit flies called Fly: An Experimental Life, by Martin Brookes, and you can find out more about the Drosophila genome at http://www.fruitfly.org/.

Image sources:

Drosophila buscki from Journal of Endocrinology

Fruit fly graphic and DrosophiLab banner from DrosophiLab

Evolution (Core)

Ecuador Hummingbirds

Ecuador Hummingbirds

Start with this reading on Evolution and Darwin: https://www.box.net/shared/6dx95t6ma6 and then watch this video of evolutionary researchers in action in Ecuador.

In the clip below, is Ross using the correct language when he describes the theory and evidence for evolution?

Here is the class presentation

And the Essential Biology notes can be found here: https://www.box.net/shared/550sxdbx82

There are many sources of interactives and animations on Evolution on the internet. Here are a few:

PBS Evolution has lots of high-quality activities and videos

BiologyInMotion has a very clear population evolution interactive

The Exploring Evolution weblab has examples of homologous structures and fossil evidence

MMHE has a pesticide resistance tutorial

And there are some good peppered moth simulations here and here

As always, sumanas has a great resource – this time on antibiotic resistance

And John Kyrk has a truly awesome timeline of the evolution of life

Darwin resources:

Attenborough on Darwin: The Tree Of Life

Dawkins Darwin Lectures from OU/BBC

And of course, all of Darwin’s works are available online from darwin-online.org

And here’s Dawkins on the evolution of the eye:

Scientific American Frontiers

Thanks to bogstandardcomp from the TES Forums for this one.

Click Here

Click Here

PBS have a series on their archives called Scientific American Frontiers. Although the last episode posted there was a couple of years ago, they have full episodes online and allow easy navigation within clips. There are also teaching resources and notes to go along with each one.

For some highlights have a look at:

Make Up Your Mind (brain development and neuroscience)

Hot Planet, Cold Comfort (climate change)

Going Deep (ALVIN and deep-sea exploration)

The Gene Hunters (Genetics and a few good resources)

Genetics – Megapost

Get the Essential Biology 04 – Genetics Revision guides here:  Standard LevelHigher Level

Top websites:

Learn.Genetics@Utah awesome resources

Click4Biology Genetics pages: CoreHigher Level

BioEthics Education Project: The Human GenomeGenetic Technology

And as always, click on the shadowed images in the presentations to be taken to source videos and animations.

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Here are all the presentations for the Genetics topics.

Core:

More presentations after the jump…

Read the rest of this entry

Protein Synthesis: Transcription and Translation (2009)

This is a re-post for the class of 2009 to revise and the 2010 group to catch on the first time… As always, click on the shadowed images for a link to an animation, or visit the links posted below.

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Core (for everyone):

Click4Biology page

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Additional Higher Level:

Click4Biology page: TranscriptionTranslation

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Further resources:

There are many decent Flash animations and the like on the internet, but the majority cannot be embedded. Below this YouTube video, there are some direct links to resources, some of which can be easily saved.

Learn.Genetics @ Utah

Transcribe and Translate (good, basic, interactive)

How do fireflies glow? (puts it in context)

University of Nebraska:

Protein Synthesis overview (Good enough for SL)

Transcription Details (fits DP Bio HL very well)

Translation Details (fits DP Bio HL very well)

John Kyrk: (visit the parent site at www.johnkyrk.com – excellent)

Transcription (fits DP Bio HL very well)

Translation (fits DP Bio HL very well)

St. Olaf College

Transcription (clear and simple)

Translation (clear and simple)

EDIT:  Two more animations (from mrhardy’s wikispace, original source unknown)

Transcription

Translation

WH Freeman

RNA Splicing tutorial (HL only)

Bio3400

Translation with a genetic code dictionary (shows position in the ribosome)

Some more in-depth animations (newly added):

Translation from Wiley Interscience

Translation from LSU Medschool

Translation from The Chinese University in Hong Kong

Protein targeting from Rockefeller University

Parthenogenesis – Virgin Births in Nature

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

Parthenogenesis

Some plants, insects, shark and lizard species are known to reproduce by parthenogenesis – embryo development is carried out without fertilisation by a male -so called  ‘virgin creations.’

Parthenogenesis can take a range of pathways :

  • 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.

Komodo Dragons

Komodo Dragons

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:

Some interesting Komodo readers here from Richard Dawkins and Not Exactly Rocket Science.

Parthenogenesis in sharks

Parthenogenesis in sharks

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:

1. How does parthenogenesis differ from binary fission in bacteria, or vegetative reproduction in some plants?

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?

References:

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.


DNA Structure (Core and AHL)

This is a short one – class presentation is here (click shadowed images for animations and movies):

Here’s a decent video from BBC AS Guru with David Suzuki:

And here’s a very stylized video of DNA structure from Hybrid Medical Animation. See if you can narrate it:

The story of the discovery of the double-helix structure is a good example international collaboration and competition, and led to the Nobel prize for Crick, Watson and Wilson (who we never hear about). You’ve got to feel for Rosalind Franklin – her work was key in their discovery and she wasn’t cited for it until after her death.

Here’s a great video, though the presenter sound like he has a mouth full of marbles:

Secrets of the Sequence – The Discovery of DNA

This 9-minute clip is an ideal ‘watcher’ to go along with the reader in the Course Companion – it tells the story of the discovery of the DNA double helix structure by Watson and Crick and how their discovery was dependant on the prior work of Rosalind Franklin and the compeitive/cooperative nature of research:

This clip  is taken from the vdeo lesson resource provided by Virginia Commonwealth University’s ‘Secrets of the Sequence’ website. They have 50 different videos, each with accompanying lesson plans and activities.

They also have a YouTube channel: VCULifeSciences.

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