If human and worm DNA are so similar, why are we so different?

If human and worm DNA are so similar, why are we so different?

There are certain major genes, sometimes called Hox genes and sometimes called developmental genes, that switch on a whole suite of other genes. They are simply like switches in early developmental processes. To give an example that's a little bit closer to home, look for the nearest man and see how different you are from that person. Now although not everything that's different is down to one gene, the fact that you are female and he is male is down to a single gene called SRY. Very early in development, if SRY is present it makes testes, and if it's not, ovaries are made. So you've got just one single gene that switches over from one type to another, and then everything else follows from that, including the hormones produced by testes and ovaries. In worms, they've got a different set of these Hox genes, which start the whole process off. They're switching on a completely different set of genes in a different order, and so the developmental process is utterly different.

What would happen if a bird drank fizzy water ?

What would happen if a bird drank fizzy water ?

Legend says that giving birds fizzy water can make them explode as gas builds up in their stomachs. But this is probably not correct - birds can burp it up. Bird's guts are somewhat different to humans, containing different chambers, but they do have an oesophagus which allows the bird's food to reach the crop (where a human's stomach would be). As bird's have no teeth they swallow food whole. It travels down to the crop ready for regurgitation to feed their young. It follows that, if they can regurgitate food, they should be able to regurgitate gas too. However it's not really natural for birds or other animals to drink fizzy water so best to stick to still water for your pets!

Where does all the sand in the Sahara desert come from?

Where does all the sand in the Sahara desert come from?

Sand is tiny fragments of rock. When rock wears down you get smaller bits of rock, or pebbles, and when they wear down you get even smaller bits and eventually you get down to sand, or silica. The reason it ends up washing up on the beach is that the sea or wind can move sand around very easily while rocks are more likely to stay put. This separates things by size, and the sand ends up on the beach and the rocks end up on the seabed. There were lots of sand stones in the Sahara which have weathered and broken down over time from rain, and sun and wind. This has produced accumulations of sand which have built up over time to produce this massive desert. Rocks are made up of lots of different things other than silica, or quartz. But the silica is the toughest material which is why it gets left over after a lots of weathering, when everything else has dissolved or turned to dust.

What is global dimming?

What is global dimming?

When you put particles into the air, such as from cars, industry and volcanoes, the particles reflect some of the sun's rays back into space and stop it coming through into the atmosphere. The sun is the key source of warming and energy input into our planet. So actually in real terms when you have a big volcano, despite the fact that it releases an enormous amount of heat, it releases an enormous amount of ash. That correspondingly cools the planet. Most people might think that volcanoes would heat the planet up, but they actually cool it down for quite a long time. A recent piece of research in the journal Nature showed that Krakatoa, which blew up over Indonesia about 100 years ago, still has a legacy living on in the oceans today. Over 100 years later we can still see a cold body of water and lower sea level because of that.

How does the weather affect weaker ocean currents?

How does the weather affect weaker ocean currents?

In terms of the ocean affecting the weather, the ocean has a very strong influence on seasonal weather. If you're talking about needing weather predictions several months ahead, then you do very much need to look at the ocean temperatures. In fact, if we look at this last winter, it's been incredibly dry here in the UK. That's been closely connected to the fact that we've had incredibly warm sea temperatures in the tropical Atlantic. If we look back to the autumn we had lots of hurricane activity including the one in New Orleans, and that was also connected with sea surface temperatures. For European winters, you have one of two situations. You either have the case where you have a very strong jet stream that brings all the storms across the Atlantic to the UK. In those situations you'll typically have warm, wet winters. The other situation is where you have a much weaker jet stream and the storms tend to get deflected up north or down south. In those situations you typically have a cold, dry winter in the UK. Whether or not you're in one or the other situation is largely modulated by the sea surface temperatures are like in the Atlantic Ocean.

What are flames made of?

What are flames made of?

Flames are simply soot particles made when a wick (in the example of a candle) burns. Because these soot particles are so hot, travel upwards and glow, just as a red hot poker might glow. They glow a yellow colour and so create a flame.

What gives us a toothache?

What gives us a toothache?

A toothache is when you have irritation to the nerve supply to a tooth. The most common reason for this is sensitivity to cold, when you have sensitive teeth, but usually it’s because you have a hole in your tooth – a carie. Holes in teeth are caused by bacteria, usually streptococcal bacteria, metabolising sugars in your diet into acids, which then drill holes in teeth. Teeth are made of calcium phosphate, and so can be dissolved by acid.

When the hole becomes big enough, the bacteria can start to change the chemical environment inside the tooth, and you can get abscesses. These are painful because they cause inflammation and swelling, or just because of the change in chemistry.

Another less common, but very serious cause of toothache can be an infection in a sinus. The nerves that supply your teeth run through, for example, the floor of the maxillary air sinus, the sinus behind your cheek. An infected sinus could make you feel that you have a toothache, when there’s nothing wrong with your teeth.

When you put wood on a fire, why does some wood spit and crackle while other wood burns slowly and quietly?

When you put wood on a fire, why does some wood spit and crackle while other wood burns slowly and quietly?

There are a couple of reasons for this. It's usually to do with how dry the wood is. What splits the wood apart is the expansion of pockets of water vaporising as the wood gets very hot. The expansion is like its own mini explosion.

What's the difference between fuel sold in the winter and in the summer?

What's the difference between fuel sold in the winter and in the summer?

Fuel is different between winter and summer because the conditions it is used in are different. The starting conditions are particularly different, as engines have to get going from a much lower temperature. What you can do to winter fuel is add chemicals that make the petrol vaporise at a lower temperature, which facilitates cold starting. Using a better mix makes it easier for your car to start on a very cold day.

What would happen if you lit a match in space?

What would happen if you lit a match in space? Considering there's oxygen in the air on a space station but no up or down, what would be the structure of the flame?

A flame goes upwards because of convection. The hot gas created by the flame rises. As you say, there's no up or down in space so the gas just forms a sphere around where it's burning and you just get a sort of circular flame. But actually stuff doesn't really burn very well in space. This is because the process of the gas going upwards (as happens on Earth) gets rid of the carbon dioxide formed in the burning process and sucks in more oxygen to keep the flame stoked. This keeps everything burning quickly. As there's no upward movement of gas in space, you don't have much oxygen getting into the flame and it's quite a poor flame that is formed. So essentially it chokes itself in its own waste products and just goes out.

Why do cars smell like rotten eggs after a while? Is this down to catalytic converters?

Why do cars smell like rotten eggs after a while? Is this down to catalytic converters?

This is not exactly a myth but is something that's becoming less of an issue nowadays. The reason that that happens is that there is sulphur in fuel and when sulphur burns in oxygen it forms sulphur dioxide. This only really happens in a petrol engine, which can operate under fuel-rich or fuel-lean conditions. In fuel-lean conditions there's quite a lot of oxygen so the sulphur in the fuel gets oxidised to sulphates. This is a real pain because this clogs up the catalyst and builds up on the surface of the monolith. But when you start a car, this is the point when you have fuel-rich conditions. This is going to convert the sulphate that has built up on the catalyst into H2S, which is hydrogen sulphide. That's the kind of eggy smell that you get out. But this is also why we're getting a lot more low-sulphur fuels nowadays and to be honest it's a lot less of a problem than it used to be.

Why do pictures fade in paintings and books? Is it a chemical reaction?

Why do pictures fade in paintings and books? Is it a chemical reaction?

The colours in pictures are made out of chemicals. They tend to be chemicals that interact with light quite well because they have a colour, meaning that they absorb some colours and reflect others. If they are exposed to too much light, especially ultraviolet light from the sun, they break, become damaged and stop being coloured. It depends what dyes you're using. Inorganic dyes that include metals tend to survive a lot better in sunlight than organic ones, but basically the chemicals get damaged and bleached. If the molecule is broken by absorbing lots of UV light, then its absorbency changes. The same thing happens with human hair in summer. You can make the process happen a little bit quicker if you put some lemon juice on. On a similar point, the reason why bleaches work is that dye molecules are sensitive and quite easily damaged. A bleach is something which oxidizes something, and goes round and damages things at random. The things that get damaged first tend to be the colour molecules and so things tend to go white.

Why does your stomach rumble when you are hungry ?

Why does your stomach rumble when you are hungry ?

The rumbling sounds you hear are your stomach gearing up to accept food. Whenever we feel hungry we usually placate our stomachs with some food soon afterwards and so the digestive system prepares itself in advance by releasing digestive juices and increasing the peristalsis of the stomach muscles. When we eat the food dampens the sound of the juices squirting around so the stomach sounds quiet. When we are empty though there is nothing to soak up the sounds and the result can be noisy !

Why can birds sit on a power line and not be electrocuted ?

Why can birds sit on a power line and not be electrocuted ?

The reason that birds can sit unharmed on power lines is that no current flows through them because they are not completing the electrical circuit by sitting on one line only. Rather like water flowing down hill, electricity needs to flow down an electrical hill, otherwise known as a potential difference. So if you connect the plus side of a battery to the minus side current flows because there are lots of positive charges at the plus pole and very few at the negative, so the current flows to try to equal things out. So going back to the bird sitting on a power line, no current flows through the bird because it has the same charge as the wire it is sitting on. If it were to straddle a positive and a negative line, on the other hand, it would certainly be curtains ! Ditto if it put one leg on the ground and another leg on the wire. Under these circumstances there is a big difference between the amount of charge in the wire and the charge on the ground, so electricity would flow through the bird in an attempt to balance things out.

Since skin continuously replaces itself, why do tattoos last a lifetime ?

Since skin continuously replaces itself, why do tattoos last a lifetime ?

The upper layer of the skin, the epidermis, which consists of flattened dried-out dead cells, is replaced continuously throughout life. As cells are worn away from the top layer of skin they are replaced by new cells from below. Tattoos are injected deeper into the skin into a layer called the dermis below where the cells that make the epidermis come from. This means that the dye stays where it is put for life.
Show featuring dermatologist Jane Sterling about the skin and skin diseases

What is a mirage?

What is a mirage?

A mirage is a trick of light seen in hot places like deserts (hence the association with thirsty travellers) and road surfaces. Like the end of a rainbow (another light trick) you can never actually reach a mirage. They form because when air is heated up light rays pass through it more rapidly, causing them to bend, or refract, upwards. They bend upwards because warm air close to the road surface, for instance, allows the light to pass through more rapidly than cooler air higher up, but when the rays reach your eye they are interpreted as coming from the road surface (like a reflection), rather than the sky, and so you see a mirage.

How big is the internet ?

How big is the internet ?

This depends on whether you mean how many pages are there, or how many people are there using the web ? In terms of the number of pages, the search-engine Google claims to currently index over 2 billion. In terms of the size of the online community, current estimates suggest about 544 million people, according to internet demographics source nua.com.

How fast do sperm swim?

How fast do sperm swim?

About 3 mm per minute. Interestingly, scientists have found that mouse sperm are very altruistic and line up nose-to tail to swim along in convoy, thus helping more of them make it further. In humans, results announced by Brazilian scientists at a meeting of the American Society for Reproductive Medicine meeting in San Antonio, reveal that sperm motility can be increased by caffeine. Dr Fabio F. Pasqualotto, a human reproductive medicine specialist at the Conception Center for Human Reproduction, University of Sao Paulo, Brazil, compared semen samples from 232 non-coffee-drinkers, 156 men who drank 1 to 3 cups daily, 198 men who drank 4 to 6 cups daily and 164 heavy drinkers who consumed more than 6 cups per day. He found no differences in the quality of the sperm in all cases but did observe that the sperm from the coffee drinkers appeared to be in more of a hurry, suggesting that a cup of coffee could boost fertility! Meanwhile, another way to speed up sperm is to send it into space. German researcher U. Engelmann measured sperm swimming speeds aboard a European Space Agency mission in 1988 and found that the cells moved faster under microgravity conditions.

What do you mean by 'dust'?

What do you mean by 'dust'?

Well, by dust, we’re talking about small particles, because remember that when things form to start with, they don’t necessarily have to form big things and then be ground down into little things. Small things will attract other small things because they’ll stick together, one way or another. So when we’re talking about dust, we’re talking about amorphous materials that can include big bits, small bits, and bits of gas. So it’s a way of not having to define exactly what that entity is, but saying it’s a mixture of chemical entities which have all of the necessary pre-requisite ingredients to actually form planets and stars.

What is tryptophan? Does eating turkey really make you sleepy?

What is tryptophan? Does eating turkey really make you sleepy?

There's been a question about sleepiness caused by tryptophan in turkey and this is a popular myth in the United States that a feeling of sleepiness arises after the Thanksgiving meal and it's caused by the Thanksgiving turkey having a high content of a substance called tryptophan. Tryptophan is an amino acid, one of the building blocks of protein which means that pretty much all proteins contain some Tryptophan but turkey's not unusual in its tryptophan content. It has about the same amount as chicken or beef. Tryptophan is involved in the desire to sleep after a heavy meal but only indirectly. The root cause of the drowsiness but only indirectly. The root cause is the large carbohydrate intake that usually accompanies a celebratory festive meal. All those roast potatoes, the stuffing, not to mention sugar-rich puddings. They all result in a burst of insulin in the blood stream as the body tries to cope with this influx of sugars. One of the side-effects of this secretion of insulin is that tryptophan gets into the brain more easily and once there part of the tryptophan is transformed into a substance that's called melatonin. Melatonin is a hormone involved in sleep regulation and it can encourage sleep. But really it's the carbohydrate in a heavy meal that triggers drowsiness and tryptophan is just a bit player in the biochemical consequences of over-indulgence in carbohydrates.

How does the Richter Scale work?

How does the Richter Scale work?

The Richter Scale, contrary to popular perception, is actually just derived for California. It's a measurement based on the displacement measured on a seismograph. This measures the displacement of the Earth due to ground motion. It's an empirical measure, and also logarithmic. If you take a magnitude 5 and a magnitude 6 earthquake, the magnitude 6 will be bigger in terms of energy release than a magnitude 5. But a magnitude 7 will be roughly 1000 times bigger than a magnitude 5.

How much water is actually produced by a human on an average day of metabolism?

How much water is actually produced by a human on an average day of metabolism?

About a third of a litre per day is the amount of water that your body makes just through metabolising, just by burning sugar because the equation is glucose: C6H12O6. If you burn that using six molecules of oxygen: plus 6 O2, this goes to 6 molecules of carbon dioxide: six CO2 plus 6 H2O, six water molecules, and that all adds up to about a third of a litre a day which is why you get some of the water that you need from actually your own metabolism.

Why does the body needs salt and what happens if you have low salt levels?

Why does the body needs salt and what happens if you have low salt levels?

The reason the body needs salt is because every single one of our cells contains large amounts of salt and, salt is the generic term for ions, charged particles, and most of the cells in our body in fact, all of the cells in our body are electrical. In other words they pump these ions from one side of their cell membrane which is a lipid or oily substance and therefore an insulator so they pump ions from one side of that membrane to the other and this means there is an electrical potential difference across the membrane of a cell and this means that this gradient this electrical difference can be used by the cell to do other sorts of work. So cells for instance do have channels that sodium can flow in to the cell and it comes down its potential difference in concentration gradient and the result is that it can be used to pull in glucose at the same time. So sugars can get into cells.

So we need salts in our cells - that’s how they regulate their size by bringing water in by osmosis. That’s how they regulate electrical activity. Nerve cells for instance couldn’t carry information without actually having this electrical gradient across the membrane because all that’s happening when a nerve cells fires off an impulse is that you get a sudden flood of sodium in to one patch of a nerve cell. This brings in lots of plus in to that part of the cell and therefore an electrical signal goes whizzing goes down the nerve and gets built up and regenerated as it goes down the nerve and it travels at about 50 to a 100 meters a second so very rapid transmission of information.

So we need salts in our body, we take in salt in our diet, we absorb salts and those salts are also include important things like calcium to make your bone strong but you’re also losing salts all the time when you go to the toilet for example you lose calcium, you lose phosphates. This is both in urine and faeces so you have to continuously top up the number of salts that you have in your body because you have obligate or insensible losses.

The body is very good at scavenging salt from what you eat and what you drink so it’s very rare for people to get too lower levels of salt in the body based on diet alone. Usually there’s something pathological going on. Sometimes what happens is that people have a problem called syndrome of inappropriate ADH. This is anti-diuretic hormone and the body saves too much water so it scavenges back water and as a result your blood can become too dilute and you have very low sodium levels and this can cause problems with your brain swelling. It can also cause the accumulation of water elsewhere around the body and it can cause heart failure so a bad thing to have. But that can cause low salt levels that can make people feel dizzy.

Does laughing gas really make you laugh?

Does laughing gas really make you laugh?

Yes, it kind of does. Laughing gas is nitrous oxide, and it acts as an anaesthetic-type agent. It makes your brain feel a bit woozy in the same way that alcohol does. As a result, if you take some laughing gas, you fell a little bit drunk and a little bit cheerful. If you have enough of it, you start to feel a little bit sleepy, but it's very good at pain killing. If you're having an operation, it's sometimes used with other anaesthetics to kill pain and make you more comfortable. There is a sub-set of people in the population that have a particular form of a gene that is involved in making new blood cells. If they have this sub-set and have laughing gas, then it can affect their bone marrow in the long term. It can make your bone marrow work less well. Luckily, it's only temporary, but I don't think that I'll be inhaling lots of laughing gas.

What is the fifth taste you can sense on your tongue?

What is the fifth taste you can sense on your tongue?

The fifth taste is umami. This has been known for a very long time in the East, and is called umami because the Japanese recognise it. It's only in the last 20 years that it's really been recognised in the West as well. Umami is the sense that is triggered by monosodium glutamate, which I'm sure you know is in soy sauce and food from Chinese restaurants. But most people don't realise what it really is. It's actually very common and is found in tomato puree and it's in parmesan cheese.

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

It is very difficult to fake identity cards properly. Using bank notes as an example, an immense number of security measures have been put into them. Many of these measures are very hard and expensive to fake. One security feature on bank notes is the use of phosphors that give off different colours under light. Therefore, despite concerns about ID cards, they shouldn't be easy to forge.

Is it dangerous to live 500 metres away from a mobile phone mast?

Is it dangerous to live 500 metres away from a mobile phone mast?

It's far less dangerous than using the phone yourself. No one's actually found a dangerous relationship with using a phone. When you use a phone, that transmitter is a couple of centimetres away from your head, and the strength of the signal goes down with the distance squared. So it's going to be thousands and thousands of times weaker than your mobile phone right next to your head.

To explore the science of this - if you look at the energy of a microwave, and the reason we have these things in our kitchen and cook with them and we are happy to put a microwave source or a mobile phone to the side of our heads, is because the energy in the wave of a microwave is not sufficient to break chemical bonds in the same way that an x-ray or a gamma ray, or more intense forms can. And therefore they're viewed as non-ionising forms of radioation, and are viewed to be safe. That said, there's no evidence that if you do expose your nervous system to these things that they won't have a temperature effect; because we think that they might warm your head up a little bit if you're exposed to a phone. But of course the mast is much further away than a phone is. But also, exposing tissue to microwaves for long periods of time may or may not have some sort of growth related effect.

Certainly in terms of cancer there isn't enough energy in phone radiation to damage DNA which is the ultimate cause of cancer. Virtually all the studies that have been done have not found a significant link between mobile phone use and cancer. The one thing we don't have is really long term data and that's hopefully coming in in the next couple of years. But the studies certainly haven't found an effect in terms of cancer.

How far is the nearest galaxy?

How far is the nearest galaxy?

The nearest galaxy to our galaxy, the Milky Way, is called Andromeda. It's about 2 million light years away, and we think it looks very similar to our own galaxy. It's difficult to know what our own galaxy looks like because we're in it, but calculations show that it's a flat spiral disc shape. For a long time, people thought that our galaxy was the only galaxy, and that any smudges they saw in the sky were nebulae, which are clouds of gas that form new stars. It was only after some more looking and calculations that people realised that these smudges were too far away to be in our own galaxy. Even Einstein fell foul of misconceptions of that sort. When he was developing his theory of relativity, he had to put in a term that made the universe nice and stable. He thought it consisted of these fixed stars.

How do scientists measure the life of the sun?

How do scientists measure the life of the sun?

We can't actually observe any single star evolving because the time scales involved are far too long. Our sun is sort of middle aged at the moment, and is about 5 billion years old. It should be kicking around for another 5 billion years or so. The way that people understand stars is really by modelling their structure and then observing lots of examples of different stars in different stages of their evolution and seeing if the collection of observations you make fits the theory. We believe that we understand the structure of these stars and so it's really a theoretical construct. We have a model for these stars, it matches all the stars that we see. When we look at the sun, we know what kind of star it is and its properties, and we can say that it's about 5 billion years old.

Was the Star of Bethlehem a real astronomical event?

Was the Star of Bethlehem a real astronomical event?

There have been quite a lot of people who've looked into this sort of thing to see whether it was actually a real event. In fact, my lecturers when I was back at university wrote a paper on that exact same thing. He looked at the theory that if you get Jupiter, Saturn, Mars and as many planets as possible in the same spot in the sky, can you get a star bright enough to look like the Star of Bethlehem? He found that that probably wasn't the case, as it wouldn't have been bright enough. However, there are some other possibilities. These include comets, asteroids and possibly supernovae as well. When stars explode, they can give out as much light as an entire galaxy, but they don't last for a very long time. This could be an explanation.

Why as we get older do we get brown pigmented spots on our hands, and when pregnant ?

Why as we get older do we get brown pigmented spots on our hands, and when pregnant ?

We can get two sorts of colour changes as we get older and again it tends to be on the sun exposed bits like the hand and forearms. The pigment cells start to not work as well as they used to do. You can get pale spots; you can also get darker spots, which sometimes get called liver spots. I'm afraid it's part of the aging process really; the pigmentation mechanism doesn't work quite so well as it did before. In relation to pregnancy, lots of people notice that they get an increase in pigmentation, which can happen on the face, on the abdomen and around the nipples and freckles can do as well. This is because of the hormone changes increase the amount of pigment production and when you give birth and the hormones go back to normal again, those darker patches usually fade gradually.