During this cycle 3 molecules of CO2 are fixed by
3molecules of RuBP which produces 6 molecules of 3 carbon compounds i.e.
triose. From these 6 molecules 5 are required to regenerate RuBP (5 x C3
3 x C5). Therefore only one
molecule of 3C is produced generally called triose phosphate which can re-enter
the cycle or used to produce starch within the chloroplast or translocated for
+ 3ATP 3RuBP + 3ADP + 2P
In this step
the regeneration of Rubisco occurs by some Glycerate3phosphate at the expense
of ATP molecules.
+ 6ATP + 6NADPH 6GA3P + 6ADP + 6NADP + 6Pi
In this step ATP
and NADPH are used to reduce G3P into 1, 3 biphosphate and the to triose
phosphate (3 Phosphoglyceraldehyde and Dihydroxyacetone phosphate).
3CO2 + 3RuBP G3P
is the first and key reaction of Calvin cycle in which Ribulose 1, 5
bisphosphate combines with a molecule of carbon dioxide producing a six-carbon
molecule which readily breaks into two 3 carbon molecules i.e.
Glycerate3phosphate (G3P). This reaction is catalyzed by an enzyme called Rubisco
which can function as both either carboxylase or oxygenase.
molecules or for metabolism.
In this step reduced carbon is utilized either to regenerate the carbon
of phosphoglyceraldehyde by reduction of organic molecules.
is fixed into organic molecules.
There are three steps in
which this cycle completes namely,
Calvin Cycle is the second phase of
photosynthesis in which the fixation of atmospheric carbon dioxide into sugar
phosphates occurs. It is a light independent reaction hence called dark
reaction. These reactions which require chemical energy in the form of NADPH2
and ATP are collectively known as Calvin Benson Cycle.
TOPIC: CALVIN CYCLE
In the last step of citric
acid cycle malate is oxidized forming oxaloacetate. The reduction of NAD+
NADH also occurs.
In this step by hydration fumarate is
converted into malate.
In this step succinate is oxidized to
form fumarate. In this reaction two hydrogens are transferred to FAD to form
In this step the CoA is replaced by a
phosphate group which is transferred to ADP forming ATP. In some cells the
phosphate group in attached to GDP forming GTP. The four carbon molecule formed
is called Succinate.
In this step ?-ketoglutarate is
oxidized reducing NAD+ to NADH which results in the release of a
molecule of CO2. The remaining four carbon molecule combines with
CoA forming Succinyl CoA.
In this step isocitrate is oxidized hence it releases a carbon
dioxide molecule. The reduction of NAD+ to NADH also occurs.
In this step a molecule of
water is removed and then added which results in the conversion of citrate into
its isomer isocitrate.
In the first step acetyl CoA joins with oxaloacetate and releases
its CoA group forming citrate.
The Krebs cycle is also known as
‘Tricarboxylic Acid (TCA) Cycle’ and ‘Citric Acid Cycle’. It is the
intermediate process of aerobic respiration which is actually a series of
chemical reactions used by all aerobic organisms to release stored energy
through the oxidation of Acetyl Co-A derived from carbohydrates, fats, proteins
into Carbon dioxide and the currency of energy i.e. Adenosine Triphosphate.
This cycle consists of eight (8) steps (reactions) catalyzed by enzymatic
activity. In Krebs cycle the first four steps cause reduction while the last
four exhibit oxidation.
TOPIC: KREBS CYCLE
rotting fungi destroy not only living trees but also structural timber.
Bracket/shelf fungi cause a lot of damage to stored cut timber as well as
stands of timber of living trees.
cause incalculable damage to wood, fiber and leather by decomposing them.
DESTRUCTION OF TIMBER:
cause tremendous amount of spoilage of food stuff by many of the saprophytic
also cause a variety of diseases in animals such as ring worm and athletes foot
that are superficial fungal infections. Other examples of fungal infection are
aspergillosis, histolplasmolysis, etc.
cause a number of diseases in human beings like aspergillosis (ear and lung
diseases), moniliasis (skin, mouth and gums diseases). Many imperfect fungi
cause various skin diseases in human beings.
causes many diseases in plants such as late blight of potato, occurring of
black spots on apple and other members of the fruit family, loose smut of
wheat, downy and powdery mildews, etc.
DISADVANTAGES OF FUNGI
are involved in the production of various foods such as cheese.
species of fungi are edible most commonly mushrooms. They are considered to be
the delicacies of food.
ROLE OF FUNGI AS FOOD AND FOOD PRODUCERS:
They are also responsible for the synthesis of
fats from carbohydrates.
many fungi are involved in the production of many essential nutrients like
vitamins and proteins.
are involved in the refining of cheese and are responsible for the texture and
flavor of cheese.
important organic acids such as oxalic acid, fumaric acid, etc. are produced
industrially due to the biochemical activities of certain fungi especially
products of high enzymatic activity have been introduced in the market on the
basis of intensive study of enzymes produced in certain fungi.
producers of Carbon dioxide which is considered a useful product in the baking
and brewing industry they are given great importance.
is involved in the process of alcoholic fermentation i.e. fermentation of sugar
ROLE OF FUNGI IN INDUSTRIAL SECTOR:
fungal strains prevent or control certain diseases caused by some other fungi.
help in the control of insect pests.
fungi produce associations with the roots of plants and helps them in taking up
of nutrients. This association is called Mycorrhizal Association.
to their property of decomposition they convert various complex compounds into
simple compounds by secretion of certain types of enzymes. Some of these simple
compounds are then absorbed by soil which results in the formation of humus.
commercial agriculture a type of fungi i.e. saprophytic fungi cause decay and
decomposition in various bodies of dead animals and plants.
ROLE OF FUNGI IN AGRICULTURE:
than that, some antibiotics that are derived from fungi are mixed in the feed
of slaughter animals which ensures the rapid growth and enhances the quality of
the field of medicine fungi have played an important role as they are producers
of some antibiotics that can kill pathogenic organisms and cure diseases and
also inhibit the growth of some bacteria. Many different types of antibiotics
such as Penicillin, Streptomycin, etc.
ROLE OF FUNGI IN THE FIELD OF MEDICINE:
ADVANTAGES OF FUNGI
Let us first study the advantages of fungi.
In this universe
each and everything has its own economic advantages and disadvantages.
Fungi are multicellular, eukaryotic,
non-chlorophyllous, living organisms which feed heterotrophically by absorption
and have a cell wall made up of fungal cellulose and have a body made up of
hyphae called mycelium.
Before we discuss the economic importance of fungi let us have a
brief study about what fungi really are.
TOPIC: ECONOMIC IMPORTANCE OF FUNGI