What the Figures Show
Life comes in
many forms, shapes, and sizes. Today's species diversity is testimony to
the variability in form and function based on an otherwise close relationship
among organisms at the molecular level of the cell. This close relationship
makes best sense in the light of the Theory of Evolution.
As first proposed by Charles Darwin all life forms are descendants of a
common ancestor organism. All life forms use the same four nucleotide building
blocks (abbrev. A, C, G, T) for storing, replicating, and reading genetic
information. All life forms also depend on the activity of proteins which
are formed from twenty different amino acids in long chains and varying
All life depends on the activity of proteins. They are
made of amino acids arranged in a linear sequence. The information
for synthesizing the amino acid strings is found in DNA or genes.
The figure shows a part of a bacterial cell wall protein called porin.
It forms small pores across the outer part of the cell wall functioning
as a sieve protecting the cell against toxic proteins but allowing
the uptake of small nutrients. Some 12,000 plus protein
structures are known/ This number constitutes only a small fraction
of all possible protein structures of all living organisms combined.
Size of particle about 10 nanometers = 0.00000001 meter.
Bacteriophage T4 is a virus infecting
bacterial cells such as that of E.coli. The large head is a protein
coat protecting the viral genome (DNA) which will be injected into
the bacterium after the virus attaches to the bacterial cell wall
surface using its filamentous tentacles to recognize the specific
host bacterium. T4 is a member of phages with contractile tails
(long rod connecting head and fibrils). Size of organism 200 nanometers.
The separation of chromosomes during cell division.
This process is found in all eukaryotic organisms such as worms, flies,
plants, and animals. It is important for growth and development. The
picture shows the anaphase where each chromatid pair separates into
two identical chromosomes that are pulled to opposite ends of the
cell by the spindle fibers. Size of eukaryotic cell 10 micrometers.
Caenorhabditis elegans is a soil nematode found in temperate
regions and is used a model organism
by biologists since the 1960s. Its complete genome
has been published in 1999. Each worm is composed of exactly 1333
cells, including those used only during development but
die before the worm reaches its adult stage with 959 somatic cells.
Thus, a complete developmental history for each cell can be described in detail.
It has a primitive nervous system. Size of organism is 1 million nanometers
or 1,000 micrometer = 1 millimeter.
Insects like dragonflies are one of the most successful group of animals on earth. The body
plan of dragonflies appears to be several hundred million years old
and conserved in insects, with some genetic elements conserved in
higher animals, also body segmentation looks different. World wide
there are 29 families and over 5,000 species of dragonflies and damselflies
alone. Size is less than 10 centimeter. A genome representing insects is that for Drosophila melanogaster, a fruit fly. This is the first animal genome sequenced and its importance comes from the importance of Drosophila as an experimental system in genetics.
Plants are so called photoautotrophic organisms. This
means they can live from light energy and inorganic material alone
- carbon dioxide, water, and many minerals (containing phosphorus,
nitrogen, sulfur etc.). Plants produce most of the bio mass on earth
and the survival of animals including humans is completely dependent
on their existence underlining the importance of agriculture and a
clean environment. In 2000 the first complete genome of a plant model
organism - Arabidopsis
thaliana - has been published. Other plant species
have since been genetically sequenced including rice (Oryza sativa) and corn (Zea Mays), two major
give ourselves a special place in Nature that allows the development
of an artificial culture (environment) not found anywhere else in
Nature, but which affects all other organisms one way or another.
As a living organism man is closely related to all other life forms
and its evolutionary history of life has been well described. Humans
depend on food for their survival, food that only comes from other
organisms - vegetarian or animal based. The human
genome project (Homo sapiens) has been finished in April of 2003 and puts a astonishing
finishing mark to the success of the biological and medical sciences
of the 20th century. Sequencing is now pushed to include the diploid sequences of many individuals, as can be followed by the 1000 Genome Project at NCBI. In addition, both the genomes of Neanderthals as an extinct homo species and the chimpanzee (Pan troglodytes) genome as our closest relative in the animal kingdom help shed light on our evolutionary history as recorded in the genomes.
Copyright © 2000-2012 Lukas K. Buehler
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