Lichens

Lichens are complex organisms that show a mutualistic relationship between fungi and algae by possessing characteristics of both. They show polymorphism by existing in diversified forms (sometimes plant-like) with different colours, sizes, and textures. Lichens represent the close association or symbiotic association of fungi with few algae and cyanobacteria. Lichens are not plants, but at …

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T Cell

T cell or thymus cell lymphocyte is one of the immune cells, which grows in the thymus gland. It performs a significant role in stimulating an adaptive immune response. T lymphocytes are different from the other immune cells in having T-cell receptors or TCRs on their cell surface. TCRs exist as a heterodimer protein complex …

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Difference Between Photosystem I and Photosystem II

The difference between photosystem I and photosystem II is primarily due to the difference in active reaction centre and photon absorption. P700 is the active reaction centre of PS-I, while P680 is the active reaction centre of PS-II. PS-I absorbs light of a longer wavelength (between 725-1035 nm), while PS-II absorbs light of a shorter …

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Difference Between Cyclic and Noncyclic Photophosphorylation

The difference between cyclic and noncyclic photophosphorylation is mainly due to the following factors: Type of photosynthesis: Cyclic photophosphorylation occurs during anoxygenic photosynthesis, while noncyclic photophosphorylation occurs in oxygenic photosynthesis. ATP synthesis: ATP synthesis during the cyclic electron flow of anoxygenic photosynthesis is known as cyclic photophosphorylation. ATP production during the noncyclic electron flow of …

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Reaction Centre

Reaction centre refers to the site of photosynthetic reactions. Chlorophyll and pheophytin are the pigments found in a reaction centre. It comprises protein pigments that mediates light absorption and excitation of an electron to the higher energy state. Photosynthetic organisms like green plants, many bacteria and algae have membrane-bound protein complexes or reaction centres that …

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Nitrification

Nitrification is one of the crucial steps in the nitrogen cycle that occurs in soil. It is an aerobic process that involves two successive oxidation reactions, in which the ammonia first oxidizes into nitrites, and then nitrites get oxidized into nitrates. It occurs in the soil and includes members of autotrophic bacteria and archaea. The …

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Prions

Prions are the sub-viral agents, which function as proteinaceous infectious particles without a genomic RNA or DNA. They are the mysterious pathogens whose accumulation within neurons cause severe fatal and transmissible neurodegenerative diseases in humans and animals. Prions solely possess PrP proteins. The term prion was coined by a scientist named Stanley Prusiner. Prion diseases …

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Viroids

Viroids are sub-viral agents, which exist as small infectious particles. They are somewhat similar to viruses but possesses some unique properties in their evolutionary origin, morphology and functions. In 1917, Diener was the first scientist who discovered and termed the non-bacterial infectious plant pathogens as “Viroids”. Potato spindle tuber viroids (PSTV) was the first viroid …

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