Cells & Life - Convergence


Life:

spermwhalepodsleeping

A pod of sperm whales sleeping.  Click for full size image in a new window. OR Link to National Geographic article


This is some of the excellent work by Frank Gregorio on Vimeo.com.

CELLS - Molecular Mechanisms: With the power of molecular factories, Nature builds ever more complex molecules - in vast quantities. This is the powerhouse of evolution - as in DNA - Deoxyribonucleic acid - diagrammed below:

DNAanimated

People often say evolution is 1 - random and 2 - insufficient to generate something as complex as ourselves. Nothing could be further from the truth.

1 - When most people say random, they mean without direction. While these mechanisms are blind explorations of every possible niche of structure in our universe, some atoms, like some horses, are faster than others.  Thus a few efficient processes rapidly converge even through random selections of enormous numbers - trillions of trillions in every speck of matter - every second for billions of years.

Carbon is the fastest race horse and the basis of our bodies.

2 - This universe is not only sufficient to generate many beings like ourselves, it has barely scratched the surface of possibilities so far. If you really grasp the scale of this place and how vast it is, then you realize that nature has only explored a few trillions of trillions of possible arrangements here in the first 14 billion years and most still remains to be explored.  I quote the syrupy musical phrase - 

"We've only just begun.” 



To cook up many recipes:

Our Recipe for life on Earth: We have a collection of optimum conditions: 
 - temperature about 300ºK [80ºF or 27ºC],
 - a working medium of water and air, 
 - a protective atmosphere and magnetic field,
 - a set of continents floating and moving around on the magma below,
 - all stirred gently by a sizeable moon. 

Spice this up with carbon, nitrogen, oxygen, iron, etc.
- and maybe seed a few beginning amino acids from comets
- then simmer in a quiet place for a few quiet billion years. 

You have cooked up the most amazing thing - the cell. 

Cells we see today are mainly of two types:
1 - prokaryotes, related to archaeia, earlier smaller simpler cells that came first and
2 -  eukaryotes, larger modern complex cells 
that came later and led to multicell organisms. 

Celltypes

Reearching this history is very difficult because cells are soft and leave vary little fossil evidence. One thing they do leave is their effect on our environment - the air we breathe. This diagram is a little off. Prokaryotes are the size of components in eukaryotes. It seems that some prokaryotes were incorporated into eukaryotes later as what we call organelles today. Here is everybody’s favorite biology class cell - the paramecium:

Paramecium

From Nikon’s Small World competition: Paramecium showing macronucleus, water expulsion vacuolas and mouth. 

Cells also change the planet itself. The oxygen you breathe in with your air now was not there originally. It is the waste product of prokaryotes and actually poisonous to them.  But there so many of them that they inverted our atmosphere and left the air we and many other eukaryotes breathe today.

We animals are completely dependent on plants. Plants can live off air, water, minerals and sunshine - we can't. Not only do we need the oxygen that they generate as a waste product. They also make sugars, which we need. We also need some of their other products such as basic more complex molecules that we can't make ourselves.

How do we get from atoms to complex organic molecules that make cells? Well, three of the most impressive parts of cell machinery are DNA, ATP and ribosomes

DNA: Most of us now have heard of DNA, the double helix molecule shown above and in the video. DNA is a data file and stores encoded information about how to build not only cells but multicell structures. It is stored in the nucleus of the cell and during reproduction, splits down its middle to duplicate. Although the cell is microscopic, the DNA file in each cell is about 6 feet or 2 meters long. DNA may have been preceded in development by RNA which is used heavily by ribosomes to make proteins [see below].

Powering the cell: Mitochondria make ATP. ATP, second only to DNA in importance, provides the energy fuel of the body. Every day, your body manufactures many kg or pounds of ATP and burns it. Mitochondria, little organelles inside your cells, make ATP. They may have been independent prokaryotes originally that became incorporated inside eukaryotic cells.


Ribosomes are tiny organelles inside your cells, molecular factories producing proteins [long amino acid chains] for your body. There are thousands in every cell/ They pump out trillions of proteins every second.

______________________________________________

Consider this: 

Instead of life originating on Earth, life spreading across the universe - Panspermia:


______________________________________________

Finally, a primordial creature from 460 million years ago - the Horseshoe Crab 

I used to walk the beach on Tybee Island in the full moon and watch them spawn:

horseshoecrab

Click for larger image in separate window

horseshoecrabspawnfullmoon

Horseshoe Crabs Spawing on the Beach in the Full Moon, for 460 Million years.
Click for larger image in separate window

______________________________

Next >>> Humans - Emergence

______________________________

For a more detailed general explanation see: The Evolution of the Eukaryotes 

and for a technical explanation see: The Evolution of the Earliest Cells

A really good introduction to the mechanism of genetics is Dawkins' River Out of Eden.

… more ? ...

© Gareth Harris 2016       --------        Contact email: garethharris@mac.com        --------         see also: GarethHarris.com