Helix @ CSIRO

For kids, parents and teachers who love science


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Double Helix – back to basics

Adenine molecule marked with an A.

Game on! Get hands-on learning about genetics with cards like this.

Two centuries ago, nobody knew much about what made a single fertilised cell grow into a human. Or – for that matter – a dog, a sea urchin, a worm or a whale. The problem was nobody could imagine how a microscopic bag of chemicals could possibly split in half again and again, yet still have enough information to make all the different organs and tissues in the body.

Since the invention of the microscope, scientists have known many cells contain a round, dark nucleus. In the late 19th century, a Swiss physician managed to extract specific chemicals from the nucleus that he called nuclein.

Bit by bit, over the following decades, chemists worked out what was in this goopy material. There were hints that these chemicals could hold the key to what turns a simple cell into a complex organism. Finding convincing evidence took a long time.

The chemicals are acids, so they became known as nucleic acids. Then scientists found different types of chemicals that were described as bases – including adenine, thymine, guanine and cytosine. It was later discovered that they were all linked in chains.

In the early 1940s, a physicist by the name of Erwin Schrödinger gave lectures on life. He imagined a chemical with repeating units varied enough to code information. The talks were inspirational.

The pieces were coming together. Deoxyribonucleic acid (DNA) is passed from one generation to the next, carrying information telling the cell how to grow and change.

In 1953, two names became famously linked with DNA – James Watson and Francis Crick. Using an X-ray image prepared by a physicist named Rosalind Franklin, they calculated the structure of the nucleic acid. The result was the familiar twisting ladder of the double helix.

The story doesn’t end there. Even today, we’re still learning how DNA molecules change shape, combine with other chemicals and transform our cells.

Learning about DNA can seem rather daunting. To make it a little easier, we’ve developed a game. The goal is simple: competing against a partner, draw base cards from a pile, and arrange them according to a sequence. To make things a little more challenging, there are action cards that could help you, or help your competitor.

To play the Double Helix card game, download the cards and the instructions and print them out. If you don’t like the rules, don’t worry – the game is simple enough, you can change them to make up your own game. Feel free to share your own rules in the comments!

Maybe with some practise, one day you’ll make your own DNA discovery.


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The different faces of phosphorus

Burning match.

Phosphorus is used to set matches alight.
Image: Sebastian Ritter/Wikimedia Commons/CC-BY-SA-2.5

Strike a match. It lights thanks to phosphorus. This element doesn’t just have fiery applications – it’s important for life itself.

Phosphorus comes in a number of different forms, called allotropes. The two main allotropes get their names from their colours: white phosphorus and red phosphorus. Both allotropes are reactive. White phosphorus is so reactive that it can spontaneously burst into flames when exposed to oxygen. The red phosphorus used in matches is slightly more stable.

Phosphorus is so reactive that, in nature, it is only found in combination with other elements. A common combination is for one phosphorus atom to combine with four oxygen atoms to form a phosphate ion.

A number of important biological compounds contain phosphates. DNA, which holds an organism’s genetic information, contains phosphates. Adenosine triphosphate is used by cells to produce energy. In humans, phosphorus is also needed to build strong teeth and bones.

Organisms need phosphorus to survive, but too much can be a problem. Fertilisers used in agriculture often contain phosphorus compounds, which help plants grow. When these compounds find their way into rivers, streams and lakes they can also help algal blooms to grow and may damage aquatic ecosystems and lower water quality.

Run-off from agriculture as well as wastewater from homes and industry can all increase phosphorus levels in waterways. As the concentrations of this chemical are often low, it makes it difficult to remove phosphorus from wastewater before it’s released into the environment.

A team from CSIRO has come up with a new way to remove phosphorus from wastewater, called enhanced biological phosphorus removal and recovery (EBPR-r). This method uses bacteria to remove phosphorus from wastewater. While using bacteria to remove phosphorus from wastewater is not a new idea, CSIRO’s method also allows the phosphorus to be recovered. The phosphorus can then be reused to make things like fertilisers or matches.

Matches, DNA, bones, fertiliser and pollution – phosphorus is an element with many different aspects. Hopefully research such as this allows phosphorus to keep sustaining life, without overdoing it!

More information

CSIRO: New research shows phosphorus recovery from wastewater viable

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Make-a-mummy

Once again I left it to the last minute to get my mum a Mother’s Day present. To avoid this last minute rush next time, I’m going to start working on next’s years present, this year. If you’re in the same boat, why not follow my lead and make a mummy for Mother’s Day?

I’ve decided to mummify a chicken, although theoretically you could use any animal. Just make sure it’s dead. Really dead. Thankfully the chooks you get from the supermarket are sufficiently dead for this activity.

You will also need a big bowl, spoon, bicarb soda, salt, some paper towels, an old sock and a large zip-lock bag. Plus, if you do try this at home, it might be a good idea to get permission from anyone you live with. You want to make sure they’re ok with you doing a long, messy and possibly smelly experiment on a dead animal before you begin.

Raw chicken, bicard soda, salt, paper towels, metal bowl, zip-lock bag and spoon.

Here’s the stuff that you will need.

I recommend that you do this activity somewhere that isn’t a kitchen. It uses a raw chicken, there’s a lot of chicken juice involved and you don’t want that to contaminate food that people are going to eat. I also recommend that you use a tray to help contain the inevitable mess. And of course, once you’re done, remember to wash your hands thoroughly.

Start by washing the chicken and patting it dry with the paper towels. Mummification works by removing moisture, so the less moisture you have to start with, the better. Also remember to dry the inside cavity of the chicken. Usually the guts have been removed from a store-bought chook. If you’re lucky, some guts might remain. Feel free to mummify these as well.

Chicken innard.

I found this in my chicken. I don’t know what it is…

The Ancient Egyptians used natron to dry out their mummies. Natron is a naturally occurring mixture of sodium carbonate decahydrate (meaning that for every unit of sodium carbonate, there are 10 molecules of water) and sodium bicarbonate (bicarb soda). If you have access to natron go ahead and use it. I decided to go with a mixture of bicarb soda and ordinary cooking salt. Please note, you will need substantial quantities of both. If you are not prepared to get strange looks from the check-out chap at the supermarket when you buy a chicken and four kilos each of bicarb soda and salt, this activity may not be for you. I mixed together equal parts of salt and bicarb (a kilo of each) in a big bowl.

Mixture of bicarb and salt in a metal bowl.

Mix together equal parts of bicarb soda and salt in a big bowl.

Then, I spooned some of the mixture into the sock and tied the end. This is to stick in the cavity of the chicken. I expect that I will need to change the drying mixture a few times as it absorbs water from the chicken, and I didn’t want a layer of gunky, crusty salt forming on the inside of the chook. This way I can just yank the sock out, change the mixture, and stick it back in again.

Sock sticking out of a raw chicken.

Put some of the drying mixture into a sock then stick it in the cavity.

Next, I poured some of the drying mixture into a zip-lock bag, then added the chicken. I poured the drying mixture around the chicken, shaking and squeezing the bag to make sure the mixture covered the whole bird. I found that two kilos of drying mixture isn’t enough, and I made up another two kilos. This proved to be enough.

Chicken in a zip-lock bag with mixture of bicarb soda and salt.

Make sure you cover the whole bird in the drying mixture.

Once the whole chicken was surrounded by the drying mixture, I sealed the bag. I noticed that the bag had a small split in it. Rather than going through all the hassle of transferring everything to another bag, I just gaffer taped the tear.

Zip-lock bag containing white powder.

Think of it as a combined ancient history and science lesson. In pillow form.

Now the waiting begins. I think it will take at least a month, if not longer. I expect to replace the drying mixture a few times, as it absorbs the moisture from the chicken. I will leave the bag in a dry, warm place away from other food. Hopefully it won’t smell. Much.

Every week I will post an update on the desiccation situation. If you do this activity yourself, I’d love to hear how you go! Hopefully at the end I will have next year’s Mother’s Day present sorted.


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It’s almost Mother’s Day, mummy!

Looking for a mummy this Mother’s Day? Try this activity from Science by Email.

Written by Beth Askham

You will need

  • Apple

    Red apple being peeled.

    Peel your apple, ready for desiccation.

  • Table salt
  • Bicarb soda
  • Vegetable peeler
  • Teaspoon
  • Plastic container or bowl that fits an apple
  • Clear nail varnish or PVA glue (optional)

What to do

  1. Peel the apple. Young scientists should ask an adult for help.

    Hand holding an apple with a face carved into it.

    Carve out a face in your apple head. Does it look like your mummy?

  2. Using the teaspoon, carve out the features of your mummy’s head in the apple. (You could make it resemble your mum for Mother’s Day!)
  3. Mix 1 part bicarb soda to 5 parts salt so you have enough to completely bury your carved apple. Now totally immerse your apple head in salt and bicarb!This is easiest if you pour some of the salt and bicarb mix into the container, place your head on top and then pour in the rest around the head.
  4. Leave your head alone in the mixture for several weeks.
  5. You can then remove the apple head from its salty tomb. You should have a wonderfully dry, wrinkled apple mummy skull.

    Apple resembling a face in a pile of salt and bi carb mix.

    The salt around the apple is an example of a desiccant – it absorbs the moisture in its surroundings, in this case the apple.

  6. If you are feeling macabre you can decorate it with button eyes and some human hair clippings.
  7. You can also varnish your mummy head or coat it with PVA glue which will help it last for a long time. Apply the varnish in a well ventilated area.

What’s happening?

The salt around the apple is an example of a desiccant – it absorbs the moisture in its surroundings, in this case the apple.

Bacteria and mould thrive in moist environments, and drying out the apple prevents bacteria from causing the apple to rot.

Adding a coat of varnish helps prevent any moisture from getting inside the apple, and you can keep your shrunken head for archeologists to find in the future.

Applications

Dried and decorated apple resembling a head.

A decorated desiccated mummy head.

Salt was one of the ingredients that ancient Egyptians used to make mummies. To mummify a body, Egyptians would remove the brain and all the internal organs after a person had died.

A mixture of natural salts called natron was then stuffed inside and around the body. Natron salts were native to the area, and not unlike today’s bicarb soda.

After days of drying with the desiccant natron, the body was wrapped up with linen soaked in resin. The resin hardened and acted in the same way as nail varnish by stopping moisture getting inside.

Other easily available desiccants are silica gel packets (the ones labelled ‘do not eat’) and uncooked rice. Why not try the shrunken head experiment using other desiccants to see which is the most effective?

We get really serious about mummies tomorrow on Mother’s Day. Stay tuned to find out how to mummify a chicken!


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Robotic futures

Yellow submarine on a beach.

Starbug, one of CSIRO’s Autonomous Underwater Vehicles, has been used to monitor the Great Barrier Reef.
Image: CSIRO

Robots have been a popular part of science fiction for years. While robots that can think and feel like humans are still just a fantasy, robotic systems are already having an impact on our lives.

CSIRO runs one of the largest robotics research centres in the world, the Autonomous Systems Laboratory. Instead of trying to develop robots to completely replace humans, many of the projects focus on developing technology to assist humans.

One advantage robots have over humans is that they can go places dangerous or difficult for humans to get to, such as the bottom of the ocean. CSIRO’s Autonomous Underwater Vehicles (AUVs) have been used to monitor marine environments such as the Great Barrier Reef. Unlike human divers, AUVs don’t require oxygen, so they can stay underwater much longer.

Robotic systems also have applications on land and in the skies. CSIRO is a partner in Project ResQu, which developed a type of unmanned helicopter. On land, robotic systems are used in a number of industries. For example, robotic systems can be used to remotely control mining equipment, removing human operators from harsh and sometimes hazardous conditions. A bit less extreme is CSIRO’s partnership with the National Museum using robots to take remote visitors, such as rural students, on a tour of the museum.

Given the often extreme conditions robotic systems are exposed to, future research efforts will include ways to improve the durability of robotic systems. Making robotic systems ‘smarter’ and easier to use are other areas for future development.

Humans still have a number of advantages over robotic systems. We might not have a robot which can solve all our problems right now but maybe we will in the not too distant future.

More information

CSIRO: Autonomous robotic systems
CSIROpod: Robots fly to the rescue
Robogals: Robotics workshops

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Solar eclipse Friday morning!

In some areas of Australia, the Sun will appear as a ring.

In some areas of Australia, the Sun will appear as a ring.
NPS photo by Kristen M. Caldon

There’s a very special astronomical event happening on the morning of 10 May. A solar eclipse happens when the place where you’re standing, the Moon and the Sun are in line. With the Moon in the way, you can’t see a portion of the Sun!

This eclipse should be visible from everywhere in Australia, but at different times. This website takes your location, and will calculate how much of the Sun will be covered. If the calculator doesn’t work, this guide lists times for eclipse viewing in major Australian cities.

Don’t look directly at the Sun! We’ve got instructions on how to build your own solar viewer, so you can watch the eclipse safely.

In some areas of northern Australia the Moon and the Sun will line up precisely. However, unlike other solar eclipses, the Sun’s surface will still shine as a border surrounding the Moon. Scientists call this type of eclipse an ‘annular eclipse’.

So why isn’t it a total eclipse? Sometimes the Moon is further away from the Earth, and can’t cover all the Sun’s disc. This website has more details about the Moon’s orbit and how it affects eclipses.

Finally, here’s an interesting article about the historical importance of eclipses.


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No more smallpox

Smallpox vaccination kit, including a syringe, bifurcated needle and vial of vaccine.

Vaccination played an important role in the eradication of smallpox.
Image: James Gathany/Centers for Disease Control and Prevention

It’s not often that we think of an organism becoming extinct as being a good thing. However, this is the case for smallpox.

Today marks the 33rd anniversary of the World Health Organisation passing a resolution declaring that smallpox had been eradicated. Smallpox had been around for thousands of years – scars found on the mummy of Egyptian pharaoh Rameses V suggest he may have had the disease.

Smallpox was caused by the variola virus. It was highly contagious, and symptoms include fever, headache and back pain. It was also known for causing a rash of blisters that could cover the whole body. The most common strain of the virus, variola major, had a high mortality rate, killing up to 40% of people who contracted the disease. Even those who survived were sometimes left blind and disfigured by the disease.

The eradication of smallpox was made possible due to vaccination. Over 200 years it was observed that people who caught cowpox, a similar but much less deadly disease, didn’t catch smallpox. By exposing people to the cowpox virus, it became possible to prevent smallpox. This was the first example of vaccination.

Vaccination is still an important part of medicine today, and is used to prevent a range of diseases, including measles, whooping cough and chickenpox. Smallpox still remains the only infectious disease that affects human to have been eradicated. Polio is another once-common disease that has been greatly reduced, with vaccination playing an important role. Could polio be next?

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