DNA Origami

In the cells that make up your body, about 2 metres (6 feet) of DNA – strings of genes – are coiled up and packaged into a typically roundish nucleus. This nucleus is only about one hundred-thousandth of a metre wide. I’ve said before that the DNA packed into the nucleus “appears to be a tangled mess”. But looks can be deceptive.

In this great little video Carl Zimmer challenges the idea that DNA in the nucleus is arranged randomly. Job Dekker and his group are finding that the nucleus is actually very organised. Zimmer conjures up an image of tiny robots in the cell folding the DNA very precisely.

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[From Science Happens! Episode 5: Everything you thought you knew about the shape of DNA is wrong]

Some genes control other genes. Dekker’s research suggests that the way DNA folds helps this process – by bringing controlling genes close to the genes they regulate. One cause of cancer could be bad folding that interferes with this control mechanism.

Dekker’s group is trying to work out which genes lie next to each other and how DNA is folded. The answer will be extremely complex.  Dekker thinks that one day this knowledge will make it possible to fix badly folded DNA in cancer cells.

[Read more…]

Discovering DNA

In the 21st century we have an amazing set of knowledge at our fingertips. Part of this is the human genome sequence – (most of) the 3,381,944,086 letters of DNA code for a human, known as the human genome sequence. It’s publicly available and you can look it up or download it if you have a computer with internet. Maybe some of us in the developed world are even starting to take it for granted.

The downloadable sequence is just a reference – each one of us has our own unique variation of this standard. Many of us now have reason to find out the sequence for one of our own genes, for example to see if we have inherited a higher than average risk for cancer, or carry a gene for a genetic disease. It’s even possible to get your own whole, unique, genome sequenced (at a cost).

In the 1980s the human genome sequence was a dream. With the technologies available at the time we’d still be sequencing by hand. The Human Genome Project led to a lot of automated sequencing methods being developed – and they’re still being improved, which is still bringing the cost of DNA sequencing down.

This huge project was undertaken by many laboratories across the world. It was intended to be, and has been, a resource for improving health care. It’s not the only sequenced genome. Simpler organisms like viruses and yeasts with much shorter genomes were sequenced before the human, and as time goes on we’re getting genome sequences for more and more living things.

So how was the human genome sequenced? There are a range of basic techniques and tools that allow DNA to be manipulated and  read. I’ve put together a Prezi which gives a visual overview of these tools.

Prezi: Tools for DNA discovery and innovation

To see this Prezi with more detailed explanations click on the link above.

To see this Prezi with more detailed explanations click on the link above.

This  post has been cross-posted to www.chromosomesandcancer.com.

Further reading:

The Human Genome Project and cancer

The last frontier of the Human Genome Project – repetitive DNA.

https://www.genome.gov/12011238

The Wellcome Trust’s Sanger Centre has a lot of information, videos and interactive tools that help explain DNA analysis and how the Human Genome was broken down into sections and sequenced. https://www.sanger.ac.uk/about/engagement/yourgenome.html