Monday, November 30, 2009

How Water Keeps Us Alive

It's uncanny how many essential functions water serves for life processes. But perhaps the most important function is the regulation of temperature. And the amazing thing is, water acts to regulate temperature simultaneously and independently on multiple levels. On a micro sub-cellular level, a human level, a regional level, and a global level.

Life survives in a narrow temperature range that just happens to correspond with the temperature at which water is a liquid. That's not a coincidence. Life and water are tightly coupled on Earth. All of life's metabolic processes – the things that make a living organism “alive” - happen in water.

The temperature at which water is a liquid is not necessarily the temperature that's ideal for many types of chemical reactions. In some cases heat needs to be added to get a reaction underway, or a chemical reaction can produce a lot of heat in an uncontrollable chain reaction. Either way, the reaction proceeds at a temperature much too hot for life.

All biochemical reactions are catalyzed (made easier) by large convoluted protein molecules called enzymes. The key to an enzyme's function as a catalyzer of chemical reactions is its complex shape. And the key to an enzyme's shape is how the molecule twists and folds in on itself in relation to the water molecules that surround it.

Water is also necessary because it facilitates the flow of dissolved molecules that form the raw materials and the products of enzyme mediated reactions. But that's another story.

The enzymes that catalyze most biological reactions work best within a narrow range of a few degrees centering around 37 Centigrade, normal body temperature. Hotter than this and the enzymes lose their shape and cease to function. Too cold and the chemical reactions slow down too much to sustain metabolic processes.

The human body has several independent systems that work to keep the body's temperature within the narrow range necessary for life. All of these systems involve water in a crucial way and yet each uses water in a unique way.

When we are cold our circulation system shunts blood away from the extremities, where it would be more likely to lose heat to the external environment. This keeps more of the body's water within the better insulated core where it protects the vital organs.

When we are too hot our circulation system shunts more water out to the extremities where heat can be transferred out of the body. Another independent system kicks in to cool the body by secreting water in the form of sweat on the body's outer surface. On a hot sunny day the sweat on our skin evaporates cooling us off.

When we are cold another independent system come into play. We “shiver”. This is a muscular reaction that produces heat to warm the body by increasing metabolic rates and shunting blood to the large muscles of the body. Muscle cells are controlled by nerve cells, and nerve cells cannot tell muscle cells what to do without the medium of water.

So here comes the analogy. Just as water plays the major role in keeping our bodies alive it also plays the major role in keeping life on Earth alive. For it is water in all it's forms that moderates temperature on Earth's surface.

Did I already mention in a previous column that water has the second highest heat capacity of any liquid? Water retains heat. That's why we use it for radiators. But that's also why it's warmer near the ocean in winter, and cooler in the summer. Large bodies of water moderate climate, because they absorb heat and are slow to give it up.

In places far inland it's colder in the winter and hotter in the summer because these places lack the moderating influence of a large body of water. Note that the majority of the world's population lives within 50 miles of the ocean.

Water also has a huge role to play in temperature regulation via an entirely different system – the weather. Here's how it works: The Sun's radiant energy heats the surface water of the oceans. When this happens some of the surface water evaporates. It changes from it's liquid form to water vapour – a gas. In doing so it absorbs heat and cools the surface water.

Not a big deal in terms of the proportion of water that ends up in the atmosphere .001 % of Earth's total, but it's still enough to make a huge difference to the Earth's surface temperature.

The water vapour rises up into the atmosphere where it gets blown far away by the winds. The higher the water molecules rise the colder the air. Eventually the the molecules condense back to liquid and form water droplets. When this happens the latent heat of evaporation is given off into the atmosphere.

But here's the deal - where the water molecule absorbed the heat and where it gives it back can be thousands of miles apart. Thus the sun's energy powers the transfer of heat over the Earth's surface through the medium of water.

But that's not all folks. There's another couple of systems involving water in a major role that effect the Earth's surface temperature independently of the one's I just mentioned. Water freezes into ice at 0 C. Ice reflects sunlight and cools the Earth's surface. That's why during an ice age the Earth's surface gets colder.

But there's more. In the atmosphere water vapour molecules have a stronger greenhouse warming effect than carbon dioxide. This is counterbalanced both by the cooling effect of evaporation, and the fact that water molecules do not stay long in the atmosphere before gravity takes over and pulls the water down to the earth in the form of rain.

OK but there's still more. Because water, unlike most other liquids expands when it freezes, ice forms on top of liquid water and because of that ice insulates water and keeps most of it from freezing in the winter.

Used for warming and cooling, multiple independent systems involved, tightly coupled with life itself -That's Water.

Monday, November 23, 2009

Water, The Restless Creator

The cells of our body are bathed in water. It circulates throughout our bodies in our blood vessels. Water is intimately involved in all aspects of life. No other substance is as important for life.

Water is constantly moving, circulating over the Earth's surface in ocean currents, or drawn downhill to the sea by Earth's gravity, or up into the atmosphere.

Water is drawn up into the atmosphere by solar powered evaporation, it forms into clouds and falls again to Earth as rain, sometimes in the sea and sometimes on land.

When it falls on land some of it ends up as groundwater, some in lakes. But all is drawn to the sea by Earth's gravity. It is the triple actions of the Sun's radiation, the Earth's gravity, and its centrifugal motion that creates the water cycle on Earth's surface

As if to mirror what goes on on the face of the Earth, water in the form of blood is pumped and circulated throughout our bodies by our hearts. This coordinated internal flow of water provides us with food in the form of dissolved carbohydrates , dissolved oxygen, and electrolytes; It gets rid of wastes; It carries immune cells that protect us from disease, white blood cells and platelets that help to repair the body and hormones and chemical transmitters that communicate information from one organ to another.

Water is not just water. It is the universal solvent. It can hold an unbelievable amount of different molecules in solution. Water is constantly in motion, carrying things, carrying chemicals in solution, carbonic acid, which eats away at minerals and carrying sulphates, phosphates, carbonates, and oxides to the sea.

Streams and rivers carry aluminum and magnesium silicates in suspension, and carry rocks and boulders down stream , depositing sediments on the edge of the continental shelves. Over vast scales of time water recycles all the major elements of life except nitrogen.

No-one can survive without water. Not only do we have to drink it every day, but we wash in it, cook with it, clean with it, use it in manufacturing, use it in transportation, and in recreation.

Without water we wouldn't be able to make cement and even our houses would lack a foundation. It's indespensible in religion, where it signifies holiness, purity, and rebirth

Water is the mother of life. The very first living cell was born in water, All of us were conceived and gestated in water. When we are born, we are born from out of our mother's water.

We find ourselves drawn to water, and feel it's calmness, it's churning, it's raging, and it's bubbling. Houses with a water view are worth more money because of the positive psychological effect of seeing water.

But water by itself is not sufficient for life. Without the Earth in it's special relationship with the Sun, and the Earth's size and shape to hold and channel the water, life could not have existed.

What do I mean by Earth's special relationship with the Sun? We know that the Earth, unlike the rest of the planets is just the right distance away from the sun to keep most of the water on Earth in a liquid state. Not to cold to freeze everything and not too hot to boil it all away.

Water is necessary for life, but it's got to be largely in liquid form for life to have originated and for life to continue. That's because life's metabolic processes, the ways that living things get energy, all happen in liquid water.

When, cells photosynthesize it happens in water; When cells do respiration it happens in water; When cells divide it happens in water. All the molecular reactions that are necessary for life work in water and never outside it.

That doesn't mean that water isn't important to life in it's non-liquid phases. Right now 2.9 % of Earth's water is locked away in glacial ice. Over millions of years the glaciers ebb and flow creating ice ages and lowering sea levels then mysteriously stopping their advance over the Continents, retreating towards the poles and making the oceans rise during warmer times.

Water vapour is a more powerful greenhouse gas than carbon dioxide but the reason it does not play as important a role as carbon dioxide in global warming is because a water molecule only stays in the atmosphere for a matter of days, whereas a molecule of carbon dioxide can stay in the atmosphere for hundreds of years.

97% of Earth's water lies in the great oceans. Because water has one of the highest heat capacities of any substance, second only to ammonia, the Earth's oceans play an important role in moderating and regulating climate and temperature. Tune in next week when I talk about the effect of water on global temperature regulation.

Saturday, November 14, 2009

Science vs Religion

Religion and Science are two very different activities, but they are both quintessentially human endeavors.

Science is really a way of asking questions and getting answers. Scientists asks how things happen and look at antacedant causes to find the answers. But answers in science are provisional – never final. For instance, Issac Newton's Theory of Gravity was supplanted two hundred years later by Einstein's Theory of Relativity.

That's why scientific knowledge is made up of theories, not immutable decrees. Scientific knowledge is ever growing and never completed. This is different from religion where if someone adds new revelations to established scripture, it often becomes a separate religion with separate adherents, like Mormonism.

Religion, is also a way of asking questions and getting answers but it asks the question “Why?” rather than “How?” because it is really about meaning and purpose in our lives.

We are the only religious species because we don't do well if we don't have a sense of meaning and purpose in our lives. Science can also give one a sense of meaning and purpose but, because science is provisional – it doesn't give the same sense of security that religion does.

One of the reasons that science and religion conflict is because they are both about life, and life, as we have discovered, is about maintaining itself. Life is intrinsically purposive. Living creatures try to keep on living for as long as possible; They try and begat progeny; They behave purposefully.

Science has subtle problems with this because it doesn't like asking questions about purpose – that's too subjective. It would rather ask questions about physical causes.

One of the main reasons a lot of people are uneasy with scientific descriptions of life is that they sound too mechanistic and meaningless. You can get the impression from strict Darwinists, like Richard Dawkins, that life just happened to evolve purely by chance.

This offends our religious sensibilities – it certainly offends mine. Since everything about life is purposeful, I don't see how the evolution of life could all be due to chance.

But that's a religious approach, not a scientific approach. The questions: “Why does life exist?” and “Why am I here?” - that sort of thing.

I like to think that I'm here for a purpose, that the universe begat life for a purpose, that there is a meaning to life. These are concerns about my subjective experience, about my participation in life.

Science is trying to be objective, trying to approach the ideal of objectivity - which it never quite reaches, because it is provisional and never final. Science is largely uncomfortable getting mixed up in “subjective experience” But that's OK because we've got religion and our religious propensities to deal with the subjective.

We can be uneasy about mechanistic explanations of evolution and human behaviour, but some people go to the extreme of denying the existence of evolution and global warming.
When people deny that life evolved they are taking Martin Luther's extreme position that the holy scriptures trumps every other human authority, including and especially Science.

The people who wrote the Bible were not scientists, they were not really interested in the question of causes and evidence for causes. They were interested in religious questions about who we are, why we are here, why do bad things happen to us, and what happens after we die.

The people who wrote the Bible were fundamentally people. Therefore they had axes to grind, they had personal and political reasons for writing the things that they did. No living person is immune from this, especially not people who claim to be inspired by God, as recent events testify over and over again.

Whoever wrote the book of Genesis was not writing a scientific description of how life originated. He or she, was trying to get people to observe the Sabbath.

God created the world in six days and rested on the seventh. So we should observe one day in the seven day week as a holy day. That's what that story is all about. This writer had ulterior motives as do all other writers.

When scientists ask questions such as: “How old is the human species?” and “Where and how did humans originate?” , the answer from Genesis, that God created the world in six days, just doesn't cut it. It's just a way of telling people to shut up and stop asking inconvenient questions.

The evidence is all around us that life is constantly changing, that life is incredibly old, that the Earth is incredibly old, and that we, as the human race, are not all that old. We should have respect for our elders.

Monday, November 9, 2009

Eukaryotic Cells: A Symbiotic Journey

Symbiosis, is everywhere around us if we know what to look for. Lichens, those scraggly little things that grow on rocks, are half algae half fungi. Fungi and Algae are two very distant families The algae provides the ability to photosynthesize and the fungi provides the physical structure and the ability to gather nourishment from rocks. Neither of the two species that makes up the lichen can exist anymore without the other.

Coral is a creature that forms all the coral reefs in the warm waters of the oceans. Coral is both an animal and an algae. The algae is what gives coral it's colour the greens, reds, and yellows. The animal, called a polyp, is what secretes the calcium carbonate or rock hard body of the coral. If the water stays too warm for too long it kills the algae. If the algae die, the coral dies, because the animal part cannot survive without the energy it gets from the photosynthesizing algae.

The largest structure made from living creatures is the Great Barrier Reef in Australia. This is a series of coral reefs 2600 kilometers long and 344,000 square kilometers. This huge living structure is bleaching out and dying because the algae part of the coral organism cannot tolerate the warmer waters.

Trees are in symbiotic relationships with soil fungi that live on their root tips. The fungi extract minerals and chemicals from the soil and feed them to the tree and the tree is able to feed the fungi with sugars manufactured through photosynthesis in it's leaves.

Termites, which can eat wood, digest the wood with the help of specialized bacteria in their stomachs. Cows and other grass eating herbivores are able to digest the cellulose in grass because of bacteria in their stomachs. Without the bacteria, the cow would not be able to digest the grass. Without the cow, the bacteria wouldn't have access to so much fresh grass,

There are bacteria in our intestines that help us process our waste, making it easier for our intestines to absorb Vitamins B12 and K. Without these vitamins we get blood disorders. When both creatures benefit this is called symbiosis.

There is, in every cell in our body a thing called a mitochondria. Much smaller than a cell, the are about the size of a bacterial cell. The mitochondria take oxygen and sugars and join them to phosphorus creating molecules that store energy. They're like little generators inside your cell. And there can be anywhere from one to a thousand or more of these little mitochondria in each cell, especially in cells that do a lot of work like muscle cells.

In fact, mitochondria are in every type of eukaryotic cell, the type of cell that makes up just about every living thing we know about . But they do not exist in any prokaryotic cells, which is what bacteria are. That means that mitochondria originated when eukaryotic cells originated, two billion years ago, after the proportion of oxygen had increased in the atmosphere. Bacteria could live without oxygen, but eukaryotic single celled creatures with their bigger size and more complex structures couldn't have done without the extra energy that oxygen provided.

One of the most interesting things about mitochondria is that they have their own DNA. Not only that, they appear to be one of the few organelles like plastids in plants and algae, that divides by itself.

Microbiologist Lynn Margulis was not the first scientist to suggest that mitochondria and plastids were actually forms of ancient bacteria, but her version was the first to gain acceptance in the biological community. This was largely because when it became technically feasible to analyze the DNA of mitochondria and plastids separately from the cell's nucleus, scientists discovered that the DNA of these organelles was more closely related to the DNA of ancient bacteria then to the DNA in the cell's nucleus.

Something happened two billion years ago. An oxygen breathing bacteria got swallowed by or invaded a non-oxygen breathing bacteria. Instead of harming each other they benefitted each other. The new cell couldn't survive without the oxygen breathing bacteria so they too were passed on whenever the cell divided. Over time the oxygen breathing bacteria lost some of it's independence, until it too could not survive outside the cell.

All algae, all plants, all animals, all fungi, all single-celled eukaryotes came from this symbiotic combination of bacteria two billion years ago. And the evidence for this caper is in every one of our cells.

One of the reasons it took so long to accept this theory of cell symbiosis is because this didn't quite fit the Darwinian picture. Natural selection was supposed to be imperceptively gradual and stepwise. But here we have the biggest revolutionary change in biology next to the origin of life, the evolution of eukaryotic cells from procaryotic cells, occurring through the fusion of two or more types of ancient bacteria.

This wasn't a gradual series of changes in the cells' characteristics. This was a relatively sudden jump in the structure and functioning of a cell due to the joining together of two or more distinct species. It was not the slow gradual time frame that Darwin had suggested.

The evolution of dinosaurs and human beings was child's play compared to the evolution of the eukaryotic cell. And it couldn't have happened without symbiosis.