Adonis Diaries

“A short history of nearly everything” by Bill Bryson, (part 2)

How living organisms were created?

 Earth had no oxygen in its environment when it was created.  Cyanobacteria or algae break down water by absorbing the hydrogen and released the oxygen waste which is actually a very toxic element to every anaerobic organism; our white blood cells actually use oxygen to kill invading bacteria.  This process of releasing oxygen is called photosynthesis, undoubtedly the most important single metabolic innovation in the history of life on the planet. 

It took two billion years for our environment to accumulate 20% of oxygen because oxygen was absorbed to oxidize every conceivable mineral on Earth and rust it and sink it in the bottom of oceans. 

Life started when special bacteria used oxygen to summon up enough energy to work and photosynthesize. Mitochondria manipulate oxygen in a way that liberates energy from foodstuffs and they are very hungry tiny organisms that a billion of them are packed in a grain of sand.  Mitochondria maintain their own DNA, RNA and ribosome and behave as if they think things might not work out between us.  They look like bacteria, divide like bacteria and sometimes respond to antibiotics in the same way bacteria do; they live in cells but do not speak the same genetic language.  

The truly nucleated cells are called eukaryotes and we ended up with two kinds of them: those that expel oxygen, like plants, and those that take in oxygen, like us.  Single-celled eukaryote contains 400 million bits of genetic information in its DNA, enough to fill 80 books of 500 pages.  It took a billion years for eukaryotes to learn to assemble into complex multi-cellular beings.

Microbes or bacteria form an intrinsic unit with our body and our survival.  They are in the trillions grazing on our fleshy plains and breaking down our foodstuff and our waste into useful elements for our survival; they synthesize vitamins in our guts, convert food into sugar and polysaccharides and go to war on alien microbes; they pluck nitrogen from the air and convert it into useful nucleotides and amino acids for us, a process that is extremely difficult to manufacture industrially. 

Microbes continue to regenerate the air that we breathe with oxygen.  Microbes are very prolific and can split and generate 280 billion offspring within a day; once every million divisions they produce a mutant with a slight characteristic that can resist antibodies.  The most troubling is that microbes are endowed with the ability to evolve rapidly and acquire the genes of the mutants and become a single invincible super-organism; any adaptive change that occurs in one area of the bacterial province can spread to any other. 

Microbes are generally harmless unless, by accident, they move from a specialized location in the body to another location such as the blood stream, for example, or are attacked by viruses, or our white blood cells go on a rampage.  Microbes can live almost anywhere; some were found in nuclear power generators feeding on uranium, some in the deep seas, some in sulfuric environment, some in extreme climate, and some can survive in enclosed bottles for hundred of years as long as there is anything to feed on.

Viruses or phages can infect bacteria. A virus are not alive, they are nucleic acid, inert and harmless in isolation and visible by the electron microscope; it barely have ten genes; even the smallest bacteria require several thousand genes..  But introduce them into a suitable host and they burst into life.

Viruses prosper by hijacking the genetic material of a living cell and reproduce in a fanatical manner.  About 5,000 types of virus are known and they afflict us with the flu, smallpox, rabies, yellow fever, Ebola, polio and AIDS.  Viruses burst upon the world in some new and startling form and then vanish as quickly as they came after killing millions of individuals in a short period.

There are billions of species and tropical rainforests that represent only 6% of the Earth surface harbor more than half of its animal life and two third of its flowering plants. A quarter of all prescribed medicines are derived from just 40 plants and 16% coming from microbes.  The discovery of new flowery plants might provide humanity with chemical compounds that have passed the “ultimate screening program” over billions of years of evolution.

The tenth of the weight of a six years pillow is made up of mites, living or dead, and mite dung; low temperature washing just get the lice cleaner!

 Water is everywhere. A potato is 80% water, a cow 74%, a bacterium 75%, a tomato at 95%, and human 65%.  Most liquid when chilled contract 10% but water only 1%, but just before freezing it expands.  When solid water is 10% more voluminous, an utterly bizarre property which allow ice to float, otherwise ice would sink and oceans would freeze from the bottom. 

Without surface ice to hold heat in, the water warmth would radiate away and thus creating more ice and soon oceans would freeze.  Water is defying the rules of chemistry and law of physics.  The hydrogen atoms cling fiercely to their oxygen host, but also make casual bonds with other water molecules, thus changing partners billions of times a second and thus, water molecules stick together and can be siphoned without breaking but not so tightly so that you may dive into a pool.  Surface water molecules are attracted more powerfully to the like molecule beneath and beside them than to the air molecule above so that it creates a sort of membrane that supports insects.

All but the smallest fraction of the water on Earth is poisonous to us because of the salts within it.  Uncannily, the proportions of the various salts in our body are similar to those in sea water; we cry sea water, and we sweat sea water but we cannot tolerate sea water as an input! Salt in the body provoke a crisis because from every cell, water molecules rush off to dilute and carry off the sudden intake of salt.  The oceans have achieved their present volume of 1.3 billion cubic kilometer of water and it is a closed system. 

The Pacific holds 52% of the 97% of all the water on Earth.  The remaining 3% of fresh water exist as ice sheet; Antarctica holds 90% of the planet’s ice, standing on over 2 miles of ice.  If Antarctica is to completely melt the ocean would rise about 70 meters.