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Asked by anon-283594 on 28 Mar 2021.
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Enrico Ferrari answered on 27 Feb 2021:
If you could shrink down to the size of a DNA molecule you may find quite difficult to move inside it. DNA is a busy place inside and it is quite hard. Not as hard as metals or glass but harder than hard plastic or plexiglass. I guess we are lucky that DNA is hard, so that it is not as easy to damage.
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Chris Waller answered on 27 Feb 2021:
DNA is made up of a long line of repeating molecules called “nucleotides”. If you picture a bicycle chain, every individual link would be a single nucleotide. Each nucleotide is very small but since there about 3 billion nucleotides in your DNA sequence (which is found inside every cell in your body), combined there is a lot of DNA. The chain is wound up into balls about 6 micrometers wide (6 millionths of a metre) but if unwound it would stretch to about 2-3 metres long. Now that’s alot of DNA!
If you could manage to shrink yourself down and look inside there wouldn’t be much to see. Because it is so tighly wound up, it would be like looking at a giant boulder. It isn’t so easy to get inside DNA, which is a very good thing because any damage is very hard to fix and can lead to all sorts of problems for your body.
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Anna Westland answered on 28 Feb 2021:
I think of DNA like a very long piece of rope (there is about 2 meters in every cell!) with information written along it.
But it wouldn’t look very neat – most of the time it is twisted up, like thread wrapped around lots of different spools. This is to keep our DNA protected and organised (even if it doesn’t look very organised to us).
When our cells need to use a piece of information that is “written” on the DNA, the right piece is unravelled so it can be read and copied by the machinery in our cells.
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Jo Brodie answered on 28 Feb 2021: last edited 4 Mar 2021 12:04 am
Hi L3O
(The numbers in [square brackets] match a link at the end, in ‘References’, in case you want to find out more).
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I agree with Enrico and Chris – you probably wouldn’t see very much if you shrank yourself to the size of DNA. Even if you could get inside DNA it would be a little bit like being inside a ladder that’s twisted around to form a spiral (or ‘helix’). There’s a drawing at the top of this article [1] which suggests what it might look like if someone could climb up the ‘ladder’ of DNA (not actually possible!). At the top of this page another drawing shows the shape of DNA’s helical (spiral) structure and also shows why we call DNA a ‘double helix’ [2].
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If you were inside the DNA ‘ladder’ you probably wouldn’t be able to see very far in any direction (assuming there’s even enough light to see). It’s much easier to get DNA out of the cell and have a look at it that way. In fact you can do this yourself at home with some soft fruit, like strawberries, some detergent (liquid soap like shampoo) and some alcohol (ask a parent or guardian), like vodka or methylated spirits.
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GETTING SOME DNA
There are many YouTube videos which show you what you need and how to do it (the recipe, or ‘protocol’). Here’s a video using strawberries [3] and here’s a step-by-step guide from BBC Science Focus [4]. You’ll end up with some white gloopy DNA that looks a bit slimy.
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ZOOMING IN
Although you wouldn’t see that much if you looked at the DNA under a light microscope (you’d just see gooey strands) you’d see more if you used X-rays, which let you zoom in a lot more. This is probably the closest thing to shrinking yourself to climb ‘inside’ DNA. But you wouldn’t be looking *at* the DNA itself, you’d be looking at a pattern created by ‘shining’ a beam of X-rays through it.
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Photo 51 is an X-ray photograph (taken in 1952) that shows the pattern produced when X-rays pass through DNA [5]. That photograph helped scientists learn a great deal about DNA’s structure. Steve Mould has a really good video [6] which shows how to recreate a version of historic Photo 51 using a lightbulb filament and a small laser – and how you can work out, from the patterns produced, what something’s shape and measurements are likely to be.
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The DNA you’d see from the first video with strawberries is a bit like looking at a whole forest, the X-rays are like zooming in on a tree.
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Jo
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REFERENCES
[1] https://www.nature.com/articles/d41586-019-01176-9 – “The forgotten scientists who paved the way to the double helix”
[2] https://www2.le.ac.uk/projects/vgec/schoolsandcolleges/topics/dnageneschromosomes – “DNA, genes and chromosomes”
[3] https://www.youtube.com/watch?v=JofXXyFZn38 – “DIY Science: How to Extract DNA from a Strawberry – University of Leicester”
[4] https://www.sciencefocus.com/science/how-to-extract-dna-in-your-kitchen/ – “How to extract DNA in your kitchen”
[5] https://www.bbc.co.uk/news/health-18041884 – “The most important photo ever taken?”, about Photo 51
[6] https://www.youtube.com/watch?v=dqMYWldfs_k – “Shining a laser through a light bulb can reveal the structure of DNA” (always be careful with lasers, they can damage your eyes).
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For a bit more on the size difference between visible light and X-rays see BBC Bitesize’s page on the Electromagnetic Spectrum https://www.bbc.co.uk/bitesize/guides/zw4tyrd/revision/2
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(Edited to add in a bit of space between the paragraphs, with these “|”) -
Alice Cardall answered on 1 Mar 2021:
DNA is a complex structure that codes the information that makes us all different from each other. It provides the body with special and unique instructions for things such as growing, developing and functioning. If you were able to see DNA I’d imagine it would look like a spiral staircase or twisted ladder. Each step of the staircase would represent two molecules known as a nucleotides, that are joined strongly together so that they don’t fall apart easily. There are 4 nucleotides (A,T,G and C) and it is the sequence of these nucleotides that makes up our genetic code and DNA. The A nucleotide binds to the T nucleotide and the G to the C.
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Callum Thomas answered on 1 Mar 2021: last edited 1 Mar 2021 4:37 pm
That’s a very good question. For a long time, even after we had an idea that DNA existed, nobody knew exactly what it looked like. This is because it is so incredibly small, smaller than we can even see with any normal kind of microscope. That was until a chemist called Rosalind Franklin managed to shoot X-rays at a sample of DNA and work out the shape of DNA from how the X-rays “bent” around it. Her work helped scientists understand that at the smallest level DNA is made up of two very long strands that spiral around each other. Kind of like a spiral staircase where each step is made up of two different molecules joined together.
There are four molecules that make up the “steps” in total which we usually just call A, T, C and G. A molecules always join with T molecules, and C molecules always join with G molecules. The order these molecules are in is how the information is stored in our DNA, a kind of code that your cells know how to read. If you were to look inside your cells you wouldn’t necessarily see this “spiral staircase” however. As other people have said, the long strands of DNA get would up really tight kind of like a big ball of string so that it can all fit inside of your cells and not get damaged.
Other scientists would go on to win a Nobel Prize for working out what DNA looks like, but unfortunately Franklin never did. You can read about Franklin’s life and see a picture that explains her work here https://theconversation.com/sexism-pushed-rosalind-franklin-toward-the-scientific-sidelines-during-her-short-life-but-her-work-still-shines-on-her-100th-birthday-139249
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Lizzie Pendlington answered on 5 Mar 2021:
It depends how zoomed in you go! DNA is made up of a double helix that is wrapped around various proteins so it can fit in a cell (the DNA from one cell would actually be about 2 metres if you stretched it out fully 😵) so from that view in the cell it would be quite coiled up. If it was stretched out and zoomed in you would be able to see the nucleotides and sugars that make up the structures in between and around it 🧬
Comments
Claire commented on :
DNA is very, very long. In fact, a human cell’s DNA is about 3 metres long! So, how long is that? Well, a guitar is about a metre in length, so the human cell’s is 3 guitars long! The DNA has to fit into the nucleus in our cells so it has be tightly packed in. Like stuffing a sleeping bag back into its protective bag! Not easy! This would mean that there was very little room for anything else!