Electron Transport in Photosynthesis

Photosynthesis of prokaryotic cyanobacteria as well as that of eukaryotic algae and higher plants produces oxygen and the basic process is similar in them all. A form of the Hill and Bendall ‘Z’ scheme of the sequence of processes and electron transport leading from water-splitting through NADP+ reduction is explained below. Photon capture by the …

Internal structure of Chloroplast

Electron microscopy shows the chloroplast to consist of an envelope enclosing a complex of membranes, the thylakoid system often joined or stacked into grana; the lipid membranes, contrast with the background when stained with lipophilic electron dense osmium. The space between the envelope and thylakoid membranes is the chloroplast stroma. The envelope is composed of …

Plant Cells

The entire genomic DNA cannot express at a time. In this process only particular type of gene is expressed at a time, specifically leading to the production of a particular gene product which is in turn specific for a plant organ or tissue. These specific genes are responsible for the special characteristics like smell, taste, …

Photosystems

The Concept of two photosystems originated in the work of Emerson & Lewis in 1943. Working on the action spectrum  for the pigments of Chlorella (a green alga), they found that at 440-520 nm, there was very little evolution of oxygen. This is quite understandable because those wavelengths of light are absorbed by carotenoids and …

Herbicide Resistance in Plants

A weed in a general sense a plant that is considered as unwanted plants in farm fields, gardens, parks etc., and generally the term is often used to describe the plants that grow & reproduce aggressively. They are one of the major problems in crop management as they compete with crops for water and nutrients …

Light trap in photosynthesis

Of the  several photosynthetic pigments, only chlorophyll-a can convert light into chemical energy. However this does not mean that light absorbed by the other pigments is waste. On the other hand, the light absorbed by the other pigments is transferred to chlorophyll-a . This transfer may be direct or as it happens more usually, some …

Light Harvesting Complexes

Sun is the source of an incessant flow of energy which forms a range of electromagnetic spectrum, of a portion of which is perceived by us as a light. A small portion of this light between the wavelength 39-700 nm is absorbed by the chlorophylls and other photosynthetic pigments and becomes available for photosynthesis, as …

Mechanism of Photosynthesis

Mechanism of Photosynthesis Plant Physiology Plant physiology deals with the studies of life processes that are similar in many organisms. Thousands of chemical reactions are underway in every living cell transferring water, mineral salts and gases from the environment into organized plant tissue. Plants are also endowed with the property of photosynthesizing, a unique feature …