I couldn't disagree more with Professor
Dawkin's statement. If the details of experiments 40 years ago elicit
nothing momentous (when they
have been regarded for years as a monumental triumph for the evolutionary
theory, and published in virtually every book about evolution), then what
about the observations (not even experiments) occurring over 100 years
ago that led Darwin in 1859 (The
Origin of Species) to the postulational
conclusions in his theory of evolution? And hey, Richard? Surely you're
not implying that detailed criticism
is a bad thing! And hey! Do you know what
Darwin thought of his own book?
think that the history of biological evolution is the result of highly
improbable events occurring without any noticeable direction. To believe
this requires great belief
At least Professor
Dawkins admits evolution isn't progressive. "A moth has no way to change
its color over the course of its lifetime, even if it could somehow figure
out that making the change would be advantageous.
And if the moth can't adjust its color, it obviously can't transmit any
adjustments to its descendants.
A moth's acquired-pigment-(due
to sooty pollution) is no more heritable
than a suntan."
formation of carbohydrates
in living plants from water and carbon
the action of Sunlight on the chlorophyll.
The chloroplast is the site
of photosynthesis. Plants and
convert solar energy into usable chemical energy by the process of photosynthesis.
When a photosynthesizing cell catches a photon
its potency causes a reaction in the cell that affects many adjacent-
use the process of photosynthesis to convert CO2
from the air as the material for making sugar molecules.
The process is complex involving biochemical
reactions which include electron transfer through pigment
molecules and amino acid residues,
along with splitting water releasing oxygen, itself a complex process.
This amazingly effective photosynthetic
apparatus is 'difficult' to improve upon by genetic manipulation (changing
amino acid residues or introducing or deleting genes), as it works at an
consistently. Always did, or life would not be here at all, or at least,
not the way we today undertand life to be.
"Making the sugars also requires energy and electrons,
with the energy coming from Sunlight
and the electrons coming ultimately from water. And in the process, the
water that loses its electrons is converted to oxygen. Plants assemble
the sugars into a variety of carbohydrates
that are either eaten as grains, fruits, and vegetables or burned as coal
and the derivatives of oil petroleum.
"The entire process is driven by Sunlight,
whose energy is absorbed by a variety of types of pigments,
especially the chlorophylls and carotenoids. This is why plants are green:
Chlorophylls absorb blue and red light, and carotenoids
absorb blue green light, leaving only the green and yellow light to be
reflected or transmitted by leaves.
"The units by which photosynthetic organisms
capture the energy of light are called photosystems. They are somewhat
like a satellite dish antenna, in that from 100 to 5,000 pigment molecules
(called collectively the "antenna") are clustered around a central receiving
unit, which is called the reaction center. The photosystems are pigment/protein
complexes located in specialized membranes called thylakoids. In plants
and algae, these thylakoids are located inside cells in photosynthetic
compartments called chloroplasts.
"The photosynthetic pigments are held in the appropriate orientation and
position by proteins. When light
energy is absorbed by an individual pigment molecule, the molecule reaches
an excited state, and the molecule's newly acquired excitation energy is
transferred from one pigment to the next until it reaches the reaction
center chlorophyll. Here is
where the real 'magic' of photosynthesis occurs: The excitation energy
is converted to chemical energy as it is used for charge separation, in
which an electron is transferred to a neighboring pigment. The reaction
center and antenna work well together to maintain a high rate of electron
transfer, even at lower light intensities.
"The initial transfer of an electron from the chlorophyll in the reaction
center leaves an 'electron hole' in the chlorophyll that is soon refilled.
The transferred electron, meanwhile, proceeds through a long series of
electron transfer reactions, being passed along a chain of cofactors (which
are molecules bound to specific proteins). A crucial aspect of the process
is that the flow of electrons from water to NADP
also produces a proton gradient
across the thylakoid membrane.
This proton gradient is used
for synthesizing the high energy molecule ATP-(adenosine
triphosphate), which works together with electrons
on NADP in
from the air into sugars. Because the ATP and
NADP are storage molecules, they can complete their task of fixing CO2
independent of the presence of light. The set of reactions that together
achieve CO2 fixation is referred to as
the Calvin Benson cycle.-...continues
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