PLANTS CONTAIN SEVERAL ALTERNATIVE ELECTRON TRANSPORT PATHWAYS
The electron transport chain described above is shared in essentially the same form by virtually all organisms plants, animals and microorganisms. Plant mitochondria contain, in addition, several other redox enzymes, atleast two of which are unique to plants. These enzymes have been discovered largely by virtue of their insensitivity to certain classic inhibitors of electron […]
Electron Transport Chain
We noted earlier that one of the principal functions of the respiration is to retrieve, in useful form, some of the energy initially stored in assimilates. Our traditional measure of useful energy in most processes is the number of ATP molecules gained or consumed. By this measure alone, the yield from both glycolysis and the […]
Krebs cycle/ Citric Acid cycle
The second stage of respiration is the complete oxidation of pyruvate to CO2 and water through a series of reactions known as the citric acid cycle (CAC). The citric acid cycle is also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle, in honor of Hans Krebs, whose research in the 1930s was […]
Glycolysis
The first stage of respiratory carbon metabolism is a group of reactions by which hexose sugars undergo a partial oxidation to the three-carbon acid pyruvic acid or pyruvate. Occurrence: These reactions, collectively known as glycolysis, are catalyzed by enzymes located in the cytosol of the cell. Parallel reactions occur independently in plastids, in particular amyloplasts […]
RESPIRATION
AN OVERVIEW OF PLANT RESPIRATION Aerobic (oxygen-requiring) respiration is common to nearly all eukaryotic organisms, and in its broad outlines, the respiratory process in plants is similar to that found in animals and lower eukaryotes. However, some specific aspects of plant respiration distinguish it from its animal counterpart. Aerobic respiration is the biological process by […]
Cassulacean Acid Metabolism
A third mechanism for concentrating CO2 at the site of rubisco is found in crassulacean acid metabolism (CAM). Despite its name, CAM is not restricted to the family Crassulaceae (Crassula, Kalanchoe, Sedum); it is found in numerous angiosperm families. Cacti and euphorbias are CAM plants, as well as pineapple, vanilla, and agave. Comparison of CAM […]
C-4 Cycle
All plants do not follow the same Calvin cycle (C-3 pathway) in which first stable product of carbon fixation is PGA (3-C compound). In some plants the first stable product of carbon fixation is four carbon compound (malate). These plants are called C4 plants. C3 cycle and C4 cycles are running at a time but […]
Photorespiration and C-2 Cycle
Ihotorespiration (PR) is process that involves the reoxidation of products just previously assimilated in photosynthesis. The photorespiratory pathway involves the activities of at least three different cellular organelles (the chloroplast, the peroxisome, and the mitochondrion) and, because CO2 is evolved, results in a net loss of carbon from the cell. RUBISCO CATALYZES THE FIXATION OF […]
Calvin Cycle
It is light independent reaction because light is not directly required for processes but only the products of light reaction (ATP & NADPH2). During these processes carbon dioxide is converted into carbohydrates. It takes place in stroma of chloroplast and involves many reactions, each catalyzed by a different enzyme. Discovery To identify the first […]
INHIBITORS OF PHOTOSYNTHETIC ELECTRON TRANSPORT ARE EFFECTIVE HERBICIDES
Since the dawn of agriculture,man has waged war against weeds. Weeds compete with crop species for water, nutrients, and light and ultimately reduce crop yields. Traditionalmethodsofweedcontrol,suchascroprotation, manual hoeing, or tractor-drawn cultivators were largely replaced in the 1940s by labor-saving chemical weed control. Modern agriculture is almost completely dependent upon the intensive use of herbicides. A […]