Each eukaryotic nucleus encloses a fixed number of chromosomes which contain the nuclear DNA. During most of a cell’s life, its chromosomes exist in a highly extended linear form. Prior to cell division, however, they condense into much more compact bodies which can be examined microscopically after staining. The duplication …
Read More »Genome Structure in Viruses & Prokaryotes
The genomes of viruses and prokaryotes are very simple structures, although those of viruses show remarkable diversity (for a review see Dimmock et al. 2001). Most viruses have a single linear or circular genome but a few, such as reoviruses, bacteriophage φ6 and some plant viruses, have segmented RNA genomes. …
Read More »DNA Reassociation Kinetics & Sequence Complexity
When double-stranded DNA in solution is heated, it denatures (‘melts’) releasing the complementary single strands. If the solution is cooled quickly the DNA remains in a single-stranded state. However, if the solution is cooled slowly reassociation/reannealing i. e. spontaneous realignment of two single DNA strands to re-form a DNA double …
Read More »Halophytes: Salient Features, Adaptations & Classification
Plants which grow and complete their life cycle in habitats with a high salt content are called salt plants or halophytes. Usually that term is reserved only for plants which appear in salty habitats constantly and specifically. Plants occupying only local nonsalty ecological niches in an overall saline environment, or …
Read More »Salinity: Sources, Cycles & Classification
Over four-fifths of the surface of our planet is covered with a salt solution (oceans & seas) containing, among many other constituents, approximately 0.5M NaCl. Still, only very few groups of higher plants can withstand such conditions. Most terrestrial species are unable to tolerate even one-tenth of the salt concentration …
Read More »Classification of Bacteria
We all agree that classification and taxonomy of organisms are desirable and necessary in cases of biological work. But, there is much disagreement as to the best method of classifying and naming living things. The zoologists and the botanists have arranged matters in their fields fairly satisfactorily, largely on the …
Read More »Marine Phytoplankton: Productivity, Food Chain & Factors
Pasturage of the Sea The vast ocean water is about 99%, of which usually up to 200 m depth or beyond (up to 300 m, depending on the latitudes, seasons, and water transparency) phytoplankton grow constituting “pasturage of the sea”. Their photosynthetic activity contributes about 80% oxygen in the atmosphere …
Read More »Introduction to Marine Botany: Plankton
The word ‘plankton’ has been derived from a Gr. word ‘planktos’ means drifting. So, plankton is those microscopic aquatic organisms or drifters whose movement is mainly driven by water currents, waves, tides, etc. Plankton can be two types- zooplankton, and phytoplankton. Although, some of them might possess some kinds of …
Read More »Marine Botany: Oceans, Seas & Bay of Bengal
Marine Botany is the study of aquatic plants and algae that live in oceans, seas, intertidal zones and even in brackish water (more saline than freshwater but less saline than true marine environments) of estuarine zones. It is a combined branch of marine biology and botany. According to Wikipedia, Marine …
Read More »Nori Cultivation
The cultivation of nori started about 300 yrs ago around the coast of Tokyo Bay and developed gradually in many localities Bundles of twigs of trees such as oaks, cherry, etc. were set in rows on the ground as the collectors, to which nori spores attach themselves and grow. In …
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