CHAPTER
ONE
INTRODUCTION
CHLOROPHYLL (also
chlorophyI) is a green pigment found in cyanobacteria and the chloroplast of
algae and plants. Its name is derived from the Greek words chloros (Green) and
phyllon (leaf). chlorophyIl is an extremely important bimolecular, critical in
photosynthesis, which allows plants to absorbed energy from light. chlorophyIl
absorb light most strongly in the blue portion of the electromagnetic spectrum,
followed by the red portion. However, it is a poor absorber of green and
near-green portion of the spectrum hence the green colour of chlorophylI containing
tissues. CholorophyIl was first isolated by Joseph Bienaime, Caventou and
Pierre, Joseph Pelletier in 1817.
ChlorphylI gives
leaves their green colour and absorbed light that is also used in
photosynthesis.
Chlorophyll is
found in high concentrations in chloroplasts of plant cells. ChlorophyIl is
vital for photosynthesis, which allows plants to absorb energy from light.
The two
currently accepted photosynthesis units are photosystem II and photosystem I,
which have their own distinct reaction center chlorophyIls, named p680 and
p700, respectively. These pigments are named after the wavelength (in
nanometers) of their red-peak absorption maximum. The identity function and
spectral properties of the types of chlorophylI in each photosystem are
distinct and determined by each other and the protein structure surrounding them.
Once extracted from the protein into a solvent (such as acetone or methanol),
(4) (5) (6) these chlorophyII pigments can be separated in a sample paper
chromatography experiment and, based on the number of polar group between
chlorophyII a and chlorophyII b, will
chemically separate out on the paper.
The function of
the reaction center cholorophyII is to use the energy absorbed by and
transferred to it from the other chlorophyII pigments in the photosystem to
undergo a change separation, a specific redox reaction in which the chlorophyII
donates an electron into a series of molecular intermediate called an electron
transport chain. The charge reaction center chlorophyII (P680+) is then reduced
back to its ground state by accepting an electron. In photosystem II, the
electron that reduces P680+ ultimately comes from the oxidation of water into O2
and H+ through several intermediate. This reaction is how
photosynthetic organism such as plants produce O2 gas, and is the
source for practically all the O2 in earth’s atmosphere. Photosystem
I typically work in series with photosystem II, thus the P700+ of photosystem I
is usually reduced, via many intermediates in the thylakoid membrane, by
electron ultimately from photosystem II. Electron transfer reactions in the
thylakoid membrane are complex, however, and the source of electrons used to reduce
P700+ can vary.
The electron
flow produce by the reaction center chlorophyII pigments is used to shuttle H+
ions across the thylakoid membrane, setting up a chemiosmotic potential used
mainly to produce ATP chemical energy’s and those electrons ultimately reduce
NADP+ to NADPH, a universal reductant used to reduce CO2 into sugars
as well as for other biosynthetic reduction.
Reaction center
chlorophyII – protein complexes are capable of directly absorbing light and performing
charge separation events without other chlorophyII pigments, but the absorption
cross section (the likelihood of absorbing a photon under a given light
intensity) is small. Thus, the remaining chlorophyII in the photosystem and
antenna pigment protein complexes associated with the photosystem all
cooperatively absorb and funnel light energy to the reaction center. Beside
chlorophyII a, there are other pigment, called accessory pigments, which occur
in these pigment- protein antenna complexes.
A green sea
slug, elysia chlorotica, has been found to use the chlorophyII it has eaten to
perform photosynthesis for itself. This process in known as kleptoplasty, and
no other animal has been found to have this ability.
LEGUMES
A
legumes is a plant in the family fabaceae (or leguminosea), or the fruit or
seed of such a plant. Legumes are grown agriculturally, primarily for their
food grain seed (e.g beans and lentils or general pulse), for livestock forage
and silage, and as soil enhancing green manure. Legumes are notable in that
most of them have symbiotic nitrogen –fixing bacteria in structures called root
nodules. Well known legumes include alfalfa, clover, peas, beans, lentils,
lupins, mesquite, carob soyabeans, peanuts and the woody climbing vine wisteria.
Legumes trees like the locust trees (aleditsia, Robinia) or the Kentucky coffee
tree (cymnocladus dioicus) can be used in permaculture food forests.
A
legume fruit is a simple drug fruit that develops from a simple carpel and
usually dehisces (open along a seam) on two sides. A common name for this type
of fruit is a pod, although the term “Pod” is also applied to a few other fruit
types such as vanilla and radish.
USES
BY HUMANS
Farmed
legumes can belong to many agricultural classes including forage, grain,
blooms, pharmaceutical/industrial, fallow/green manual, and timber species.
Most commercially farmed species fill two or more role simultaneously,
depending upon their degree of maturity when harvested.
Forage
legumes are of two broad types. Some, like alfalfa, clover, vetch (vicia),
stylo (stylosanthes) or Arachis are sown in pasture and grazed by livestock.
Other forage legumes such as leucaena or Albizia are woody shrub or tree
species that are either broken down by livestock or regularly cut by human to
provide livestock feed.
Grain
legumes are cultivated for their seeds, and are also called pulses. The seeds
are used for human and animal consumption or for the production of oils for
industrial uses. A grain legume includes beans, lentils lupins, peas and
peanuts.
Legume
species grown for their flowers include lupins, which are formed commercially
for their blooms as well as being popular in garden worldwide. Industrially
farmed legumes include Indigofera and
acacia specie, which are cultivated for dye and natural gum production. Various
legume species are formed for timber production worldwide.