HOW DID LIFE START?

28/02/2013

BIOCHEMISTRY

HOW DID LIFE START?

How did life start on planet Earth?

How did a ball made mostly of iron floating through space come to have self-replicating, self-aware organisms on it?

This is perhaps one of the greatest questions ever to be asked of science.  

There are many answers to this question that have been put forward in history. These answers have ranged in opinion from totally theological arguments on the nature of reality, down to the constructed logic of philosophical argument. 

However, where does science truly stand on this question?

We can build information processing technology that can transmit information to the other side of the planet at the speed of light, we can build space faring ships capable of placing men and machines on other worlds, we can develop instruments of such power and accuracy that we can study particles in thousands of times of magnitude smaller than our own eyes… yet where do we stand on this?

The embarrassing truth for science is that we truly have no idea.

The biological sciences are split along lines of what could ‘possibly’ have happened.

We are still learning the laws of biology and how the whole is greater than the sum of so many small parts.

Yet there are some strong arguments that are being put forward.

Cell membranes are especially interesting to this argument because they have an interesting quality. 

The membranes of cells are made up of billions of special molecules that are both hydrophilic and hydrophobic. This means that these long heavy molecules have one half of them that is attracted to water (like sugar that dissolves), and another half which pushed water away (like an oil or a soap).

Because of this, if they are dropped into a bucket of water they bind together. The part that’s trying to get away from water groups together and the parts that are trying to get close to it, binds in what is known as a polar bind.

After a while this process forms a thin layer. This layer is what all cells are made up of. Even if you blended the molecules completely up, they would still self-assemble into this shape.

THIS IS AMAZING!

So, if in the primordial earth these molecules are naturally self-assembling into membranes, there is the potential for them to enclose around other large and complex molecules that would also have the potential to be self-replicating.

Thus kicking off the self-replicating cells of the first simple organisms.

Some serious clout has been put behind this idea in the last few years as scientists compare the molecular makeup of the really large proteins that perform so many important cellular roles in your body.

These proteins are almost always based on very heavy metals such as Iron or Zinc. 

In the primordial earth the early ocean was covered in a layer of volcanic rock. Volcanic rock is naturally very porous (round air bubbles in it from cooled lava) and rich in these heavy elements.

It is just possible, that thanks to the presence of these porous rocks loaded with heavy metals that the membrane molecules were able to encircle around an extremely complex series of molecules using iron as a base.

Basically that’s the best scenario science has to offer,

That billions of years ago a volcano exploded and spewed lava into the complex molecule laden ocean which cooled with air bubbles in in that allowed the development of a membrane that protected another compound long enough for it to absorb enough energy to self-replicate.

Wow…

Problem with this is…

This completely ignores that fact that our best models for how these complex molecules form just create a global soup of extremely long hydrocarbons,

Or, that scientists have repeatedly attempted to duplicate these exact conditions in the laboratory and have never reproduced anything that would be considered a complex compound let alone something that was alive.

The correct answer is that, “we got no idea; we got a lot of figurin’ to do yet…”

DEEP DIVING… HOW DEEP CAN WE GO?

Ever wondered what cool sciencey stuff they are teaching undergraduates at the University of Queensland?
 Every school day I will post my newly learned cool fact... Enjoy 

27/02/2013

CHEMISTRY

DEEP DIVING… HOW DEEP CAN WE GO?

What is deep diving? There are many definitions.

Anything below 30m deep is beyond the maximum recommended divers limit.

Below 40 meters, and your beyond the absolute maximum limit specified by the Recreational SCUBA Training Council.

So… How do we make it so our divers can go deeper?

Other than taking a very long time to descend and ascend to get a body used to the intense pressure, there are some amazing tricks with air we can use. 

Ok well, let’s pump some air in a tank and off we go right?

Let’s say you pump in some lovely cheap air.

Nitrogen and Oxygen are the two most common elements in our air; they are the easiest gases to compress into a cylinder for SCUBA.

Bad idea, you just killed your diver.

The problem with air is the types of gas in it. Anything below 10m has the possibility to cause Nitrogen Narcosis. 

Nitrogen Narcosis is an altered state of consciousness where you have the gradual impact that is akin to alcohol consumption or nitrous oxide inhalation.

Anything below 50m and you are potentially experiencing full blown hallucinations.

OK, so when you’re performing a deep dive, the mixture of gasses in the tank is extremely important. 

You want to make sure that you don’t have gas that’s going to cause this narcosis.

The problem is that all gasses (except for Helium and possibly Neon) have these narcotic affects; however they are many and varied in degree. All of them become more pronounced when the breather is under pressure.

When deciding what gasses to put in a deep dive tank, oxygen is an obvious first step; however, like Nitrogen, Oxygen is also a dangerous narcosis inducing gas.

So, we want the smallest amount of Oxygen mixed with something like Helium.

Therefore, to get the deepest possible dives, you must put the minimum amount of oxygen possible in a tank.

The amazing thing is that at deeper pressures you can survive off less and less oxygen. 

This is where the chemistry comes into play.

When you are under a regular amount of pressure the percentage of oxygen in the air is exactly the amount your body will breath in

Eg 21% oxygen in the air at 1 ATM means it’s like breathing in 21% oxygen

However, if you are under pressure the affect is to make it seem like you are increasing the amount of oxygen in the air.

Eg 21% oxygen in the air at 2 ATM means it’s like breathing in 42% oxygen

Using this remarkable chemistry known as ‘Partial Pressure’, SCUBA divers have gotten the oxygen level down to an amazing minimum oxygen air percentage of around 16%!!

So, for the truly deepest of the deep dives, you need to take several canisters of specially made gas, each designed for change over at your decompression stop, so you can go to the deepest depth possible without going crazy on the way down from getting high off the air alone. 

 

This being said… 66m deep is the depth at which compressed air results in what is described as ‘unacceptable risk’ of oxygen toxicity.

The world record for the deepest SCUBA drive is set at 330m

In 2005 the Guinness world records book stopped publishing the record to stop the ridiculously high death rate of those who attempted the record.

These people are crazy…

CLOUDS… HOW DO THEY STAY UP THERE?

26/02/2013

CHEMISTRY

CLOUDS… HOW DO THEY STAY UP THERE?

Solids, Liquids and Gasses are three very different forms of matter. Yet all three states of matter of the same substance can exist in the same environment. 

In the photo you can see H2O as a solid, liquid and a gas existing naturally in the same location

This happens because of the forces that occur between individual atoms and molecules. 

Say in the arctic, with an iceberg at sea, the H₂O molecules are fused together in a crystalline mesh. The water around the iceberg however, keeps them in a semi interacting liquid state thanks to the movement of the molecules. While water vapour in the air, is the result of escaping molecules with high kinetic energy.

(Interestingly enough the Polar Regions have a high relative humidity. As humidity is a measurement of the % total amount of humidity the air can take. As it is so cold, there is almost no water vapour in the air, yet humidity rates can still be high)

This is basic chemistry that we are all reasonably familiar with from high school.

But an interesting question was asked by the lecturer as to why do clouds stay in the air?

Clouds are not made up of water vapour.

They are made up of tiny water droplets and crystals of ice suspended in the air… How do they stay up there?

The answer is just as the tiny bits of dust you see dancing in a beam of light coming into your room in the morning are kept airborne, so too are the tiny droplets and crystals of water. 

These droplets and crystals are so tiny that their density (and therefore gravitational pull) is not enough to overcome the rising heat from the planet below. This rising hot air pushes with pressure upwards. As the temperature of the air cools and this pressure decreases, the droplets will hang lower and lower in the sky. Also, as the temperature of the cloud itself cools, the molecules will clump together in larger and larger droplets until gravity overcomes the upwards pressure and they fall as rain.

It also explains why clouds that are very high and very cool are wispy cirrus formations and clouds hanging low to the earth near the heat source are your large dark cumulus clouds.

THE GASTRIC BROODING FROG

25/02/2013

ECOLOGY

THE GASTRIC BROODING FROG

This story begins in the Australian sub-tropical rainforests of the Sunshine Coast Hinterland. In an area scientists consider to be one of the most pristine in the country.

It’s an area that’s characterised by rolling hills and clear running rivers. Great cattle country where the land is cleared and amazing deep green gullies full of ferns and waterfalls.

 

Large sections have been reserved as National Parks and tourists come from all over the world to marvel at the rugged beauty of the Australian bush.

 

The area is a hotspot of biodiversity and a breeding ground of amazing wildlife. Especially interesting is a type of Frog, called the Gastric-Brooding Frog. This imaginatively named amphibian is unique in the way in which is rears its young. After spawning, the female would eat the eggs!

The eggs themselves (with a large yoke for food supply and a covering of a special lipid protein that switches off the digestion process), would remain in the stomach of the mother frog until not only the tadpoles had hatched, but also until the point that the frogs were fully developed and they were ‘given birth’ out of the mouth.

This amazing biological wonder in such a beautiful part of Australia was last witnessed in the early 1980’s. 

The species in now extinct and this wonder will never again be seen in this world.

The cause of extinction is unknown. Possibly to blame would be the introduction of weeds and feral pigs, the logging of the upper estuaries where the frog was common, perhaps the spread of deadly and exotic fungus species…

The truth is these are guesses and we will never know.

Australia, a nation proud of its amazing wildlife, has a terrible history of extinction.

We have the worst rate of mammal extinction in the world and over 20% of our remaining mammals are considered threatened. Australia also has the highest rate of threatened reptile species in the world and over 15% of our birdlife are in danger. With more than 500 plants listed as endangered or vulnerable, it’s a problem of huge magnitude.

When a species as amazing and beautiful as the Gastric Brooding Frog can vanish with no explanation, we know that we need to change our paradigm.

Half the battle to save these species is understanding what is causing the decline and as young scientists we are the holders of the keys to unlock the knowledge that can save them. We must be inspired!!

As Campbell Biology’s (9^th Edition, Australian Version), Mr Noel Meyers writes 

“There are two ways to consider the challenges to the biosphere: as a depressing indictment of human activity about which we can do little except watch as passive observers, or; as an unprecedented challenge and opportunity worthy of the investment of your energy, passion and commitment. We ask you not to believe us, not in our ability to affect change. We ask you to believe in yours…”(Reece, Meyers, Urry, Cain, Wasserman, Minorsky, Jackson, Cooke, 2013)