Biological World

  1. Introduction Ribosomes are ribonucleoprotein particles that translate the genetic information carried by messenger RNA into the amino-acid sequence of proteins. In bacteria, the functional ribosome is designated 70S and is formed by the association of a small 30S subunit with a large 50S subunit. The symbol S refers to the Svedberg sedimentation coefficient, which depends on mass, shape and density; it is therefore not an additive numerical unit. Consequently, the association of 30S and 50S particles gives a 70S ribosome rather than an 80S particle. The bacterial ribosome is not a simple spherical body. It has a distinctly asymmetric three-dimensional architecture composed of recognizable projections, depressions and intersubunit surfaces that are closely related to its role in protein synthesis. A major step in understanding this architecture was provided by James A. Lake, who used electron microscopy to analyse Escherichia coli small subunits, large subunits and intact monom...

 Stöffler–Wittmann Model of Ribosome The Stöffler–Wittmann model is one of the earliest structural models proposed to explain the organization of the ribosome. It was developed by Gerhard Stöffler and Hans G. Wittmann during the early 1970s through biochemical, immunological, and electron microscopic studies. Before high-resolution techniques such as X-ray crystallography and Cryo-EM, this model provided the first detailed description of the spatial arrangement of ribosomal proteins. Scientists recognized that ribosomes are composed of ribosomal RNA (rRNA) and proteins, but their exact organization was unknown. Stöffler and Wittmann used immunoelectron microscopy, protein-specific antibodies, chemical cross-linking, and biochemical mapping to determine the positions of individual ribosomal proteins in the 70S ribosome of Escherichia coli. The model proposes that ribosomal RNA forms the central structural framework, while ribosomal proteins are arranged at specific positions on the ...

  Comparison Between In-Situ and Ex-Situ Conservation Feature In-Situ Conservation Ex-Situ Conservation Meaning Conservation within the natural habitat Conservation outside the natural habitat Main focus Species, habitats and ecosystems Selected species or genetic material Ecological interactions Largely maintained Only partially maintained Natural selection Continues under natural conditions May be altered under managed conditions Examples National parks, sanctuaries, biosphere reserves, sacred groves Zoos, botanical gardens, seed banks, gene banks, cryopreservation Genetic diversity Potentially high if wild populations are large and connected May be limited by the number of founders Management Habitat- and ecosyste...

EX-SITU AND IN-SITU CONSERVATION Biodiversity refers to the variety and variability of life at genetic, species and ecosystem levels. It provides food, medicine, fibre, fuel, ecosystem stability, pollination, soil formation, nutrient cycling, climate regulation and numerous cultural benefits. Despite its importance, biodiversity is increasingly threatened by habitat destruction, fragmentation, overexploitation, pollution, invasive alien species, climate change, disease and other human-induced pressures. Conservation biology therefore seeks to maintain biological diversity, ecological processes and evolutionary potential over the long term. Two major approaches are used for the conservation of biodiversity: in-situ conservation and ex-situ conservation. In-situ conservation protects species within their natural habitats and ecological communities, whereas ex-situ conservation protects organisms or their genetic material outside the natural habitat under controlled or managed conditio...

  Medicinal Botany: Medicinal Botany is the branch of botany concerned with the scientific study of plants used for medicinal purposes. It deals with their identification, nomenclature, classification, morphology, anatomy, cultivation, collection, preservation, chemical constituents, and therapeutic uses. Medicinal botany provides the botanical foundation for subjects such as pharmacognosy, phytochemistry, ethnobotany, pharmacology, and herbal drug technology.   Scope of Medicinal Botany The major areas covered under medicinal botany include: 1. Taxonomy and identification Accurate identification and classification of medicinal plants based on morphological, anatomical, and molecular characters. 2. Morphology and anatomy Study of roots, stems, leaves, flowers, fruits, and seeds, along with their internal anatomical features, which are important for authentication of crude drugs. 3. Cultivation and propagation Study of suitable soil, climate, irrigation, prop...

 

  Pleomorphism of Lysosomes Lysosomes show pleomorphism, which means they occur in many different forms according to their functional state. They are not always identical in shape, size, or contents. Their appearance changes depending on whether they are newly formed, involved in digestion, or storing undigested waste materials.  Lysosomes are membrane-bound organelles containing hydrolytic enzymes. These enzymes digest proteins, lipids, carbohydrates, nucleic acids, and other cellular materials. Since lysosomes perform different digestive functions inside the cell, they appear in different structural forms. This property is called pleomorphism.  The main pleomorphic forms of lysosomes are primary lysosomes, secondary lysosomes, autophagic vacuoles, and residual bodies. Primary lysosomes are newly formed lysosomes produced by the Golgi apparatus. They contain inactive hydrolytic enzymes and have not yet taken part in digestion. They are small, spherical vesicles surround...