Phagocytosis (from the Ancient Greek (phagein) ‘to eat’ and o, (kytos) ‘cell’) is the process by which a cell uses its plasma membrane to ingest a big particle (0.5 m), resulting in the formation of an internal compartment known as the phagosome. It’s a specific sort of endocytosis. A phagocyte is a cell that performs phagocytosis.

The act of a phagocyte absorbing a pathogen.
Phagocytosis is a major mechanism employed by a multicellular organism’s immune system to eliminate infections and cell debris. The phagosome then digests the ingested substance. Objects that can be phagocytized include bacteria, dead tissue cells, and microscopic mineral particles. Phagocytosis is a type of phagocytosis used by some protozoa.

Professional phagocytic cells

Light microscopic video sequence of a neutrophil from human blood phagocytosing a bacterium

Neutrophils, macrophages, monocytes, dendritic cells, osteoclasts and eosinophils can be classified as professional phagocytes. The first three have the greatest role in immune response to most infections.

The role of neutrophils is patrolling the bloodstream and rapid migration to the tissues in large numbers only in case of infection. There they have direct microbicidal effect by phagocytosis. After ingestion, neutrophils are efficient in intracellular killing of pathogens. Neutrophils phagocytose mainly via the Fcγ receptors and complement receptors 1 and 3. The microbicidal effect of neutrophils is due to a large repertoire of molecules present in pre-formed granules. Enzymes and other molecules prepared in these granules are proteases, such as collagenase, gelatinase or serine proteases, myeloperoxidase, lactoferrin and antibiotic proteins. Degranulation of these into the phagosome, accompanied by high reactive oxygen species production (oxidative burst) is highly microbicidal.

Monocytes, and the macrophages that mature from them, leave blood circulation to migrate through tissues. There they are resident cells and form a resting barrier.Macrophages initiate phagocytosis by mannose receptors, scavenger receptors, Fcγ receptors and complement receptors 1, 3 and 4. Macrophages are long-lived and can continue phagocytosis by forming new lysosomes.

Dendritic cells also reside in tissues and ingest pathogens by phagocytosis. Their role is not killing or clearance of microbes, but rather breaking them down for antigen presentation to the cells of the adaptive immune system.

Initiating receptors

Receptors for phagocytosis can be divided into two categories by recognised molecules. The first, opsonic receptors, are dependent on opsonins. Among these are receptors that recognise the Fc part of bound IgG antibodies, deposited complement or receptors, that recognise other opsonins of cell or plasma origin. Non-opsonic receptors include lectin-type receptors, Dectin receptor, or scavenger receptors. Some phagocytic pathways require a second signal from pattern recognition receptors (PRRs) activated by attachment to pathogen-associated molecular patterns (PAMPS), which leads to NF-κB activation.

Fcγ receptors

Fcγ receptors recognise IgG coated targets. The main recognised part is the Fc fragment. The molecule of the receptor contain an intracellular ITAM domain or associates with an ITAM-containing adaptor molecule. ITAM domains transduce the signal from the surface of the phagocyte to the nucleus. For example, activating receptors of human macrophages are FcγRI, FcγRIIA, and FcγRIII. Fcγ receptor mediated phagocytosis includes formation of protrusions of the cell called a ‘phagocytic cup’ and activates an oxidative burst in neutrophils.

Complement receptors

These receptors recognise targets coated in C3b, C4b and C3bi from plasma complement. The extracellular domain of the receptors contains a lectin-like complement-binding domain. Recognition by complement receptors is not enough to cause internalisation without additional signals. In macrophages, the CR1, CR3 and CR4 are responsible for recognition of targets. Complement coated targets are internalised by ‘sinking’ into the phagocyte membrane, without any protrusion

Apoptosis (from Ancient Greek ἀπόπτωσις, apóptōsis, “falling off”) is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between the ages of 8 and 14, approximately 20–30 billion cells die per day.

In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism’s life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic bodies that phagocytes are able to engulf and remove before the contents of the cell can spill out onto surrounding cells and cause damage to them.

Because apoptosis cannot stop once it has begun, it is a highly regulated process. Apoptosis can be initiated through one of two pathways. In the intrinsic pathway the cell kills itself because it senses cell stress, while in the extrinsic pathway the cell kills itself because of signals from other cells. Weak external signals may also activate the intrinsic pathway of apoptosis. Both pathways induce cell death by activating caspases, which are proteases, or enzymes that degrade proteins. The two pathways both activate initiator caspases, which then activate executioner caspases, which then kill the cell by degrading proteins indiscriminately.

In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in a wide variety of diseases. Excessive apoptosis causes atrophy, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer. Some factors like Fas receptors and caspases promote apoptosis, while some members of the Bcl-2 family of proteins inhibit apoptosis.

The initiation of apoptosis is tightly regulated by activation mechanisms, because once apoptosis has begun, it inevitably leads to the death of the cell. The two best-understood activation mechanisms are the intrinsic pathway (also called the mitochondrial pathway) and the extrinsic pathway. The intrinsic pathway is activated by intracellular signals generated when cells are stressed and depends on the release of proteins from the intermembrane space of mitochondria. The extrinsic pathway is activated by extracellular ligands binding to cell-surface death receptors, which leads to the formation of the death-inducing signaling complex (DISC).

A cell initiates intracellular apoptotic signaling in response to a stress, which may bring about cell suicide. The binding of nuclear receptors by glucocorticoids, heat, radiation viral infection, hypoxia, increased intracellular concentration of free fatty acids and increased intracellular calcium concentration, for example, by damage to the membrane, can all trigger the release of intracellular apoptotic signals by a damaged cell. A number of cellular components, such as poly ADP ribose polymerase, may also help regulate apoptosis. Single cell fluctuations have been observed in experimental studies of stress induced apoptosis.

Before the actual process of cell death is precipitated by enzymes, apoptotic signals must cause regulatory proteins to initiate the apoptosis pathway. This step allows those signals to cause cell death, or the process to be stopped, should the cell no longer need to die. Several proteins are involved, but two main methods of regulation have been identified: the targeting of mitochondria functionality, or directly transducing the signal via adaptor proteins to the apoptotic mechanisms. An extrinsic pathway for initiation identified in several toxin studies is an increase in calcium concentration within a cell caused by drug activity, which also can cause apoptosis via a calcium binding protease calpain.

Cell culture is the process by which cells are grown under controlled conditions, generally outside their natural environment. After the cells of interest have been isolated from living tissue, they can subsequently be maintained under carefully controlled conditions. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (CO₂, O₂), and regulates the physio-chemical environment (pH buffer, osmotic pressure, temperature). Most cells require a surface or an artificial substrate (adherent or monolayer culture) whereas others can be grown free floating in culture medium (suspension culture). The lifespan of most cells is genetically determined, but some cell culturing cells have been “transformed” into immortal cells which will reproduce indefinitely if the optimal conditions are provided.

In practice, the term “cell culture” now refers to the culturing of cells derived from multicellular eukaryotes, especially animal cells, in contrast with other types of culture that also grow cells, such as plant tissue culture, fungal culture, and microbiological culture (of microbes). The historical development and methods of cell culture are closely interrelated to those of tissue culture and organ culture. Viral culture is also related, with cells as hosts for the viruses.

The laboratory technique of maintaining live cell lines (a population of cells descended from a single cell and containing the same genetic makeup) separated from their original tissue source became more robust in the middle 20th century.

Concepts in mammalian cell culture

Cells can be isolated from tissues for ex vivo culture in several ways. Cells can be easily purified from blood; however, only the white cells are capable of growth in culture. Cells can be isolated from solid tissues by digesting the extracellular matrix using enzymes such as collagenase, trypsin, or pronase, before agitating the tissue to release the cells into suspension.^[6][7] Alternatively, pieces of tissue can be placed in growth media, and the cells that grow out are available for culture. This method is known as explant culture.

Cells that are cultured directly from a subject are known as primary cells. With the exception of some derived from tumors, most primary cell cultures have limited lifespan.

An established or immortalized cell line has acquired the ability to proliferate indefinitely either through random mutation or deliberate modification, such as artificial expression of the telomerase gene. Numerous cell lines are well established as representative of particular cell types.

Maintaining cells in culture

For the majority of isolated primary cells, they undergo the process of senescence and stop dividing after a certain number of population doublings while generally retaining their viability (described as the Hayflick limit).A bottle of DMEM cell culture medium

Aside from temperature and gas mixture, the most commonly varied factor in culture systems is the cell growth medium. Recipes for growth media can vary in pH, glucose concentration, growth factors, and the presence of other nutrients. The growth factors used to supplement media are often derived from the serum of animal blood, such as fetal bovine serum (FBS), bovine calf serum, equine serum, and porcine serum. One complication of these blood-derived ingredients is the potential for contamination of the culture with viruses or prions, particularly in medical biotechnology applications. Current practice is to minimize or eliminate the use of these ingredients wherever possible and use human platelet lysate (hPL). This eliminates the worry of cross-species contamination when using FBS with human cells. hPL has emerged as a safe and reliable alternative as a direct replacement for FBS or other animal serum. In addition, chemically defined media can be used to eliminate any serum trace (human or animal), but this cannot always be accomplished with different cell types. Alternative strategies involve sourcing the animal blood from countries with minimum BSE/TSE risk, such as The United States, Australia and New Zealand, and using purified nutrient concentrates derived from serum in place of whole animal serum for cell culture.

Plating density (number of cells per volume of culture medium) plays a critical role for some cell types. For example, a lower plating density makes granulosa cells exhibit estrogen production, while a higher plating density makes them appear as progesterone-producing theca lutein cells.

Cells can be grown either in suspension or adherent cultures. Some cells naturally live in suspension, without being attached to a surface, such as cells that exist in the bloodstream. There are also cell lines that have been modified to be able to survive in suspension cultures so they can be grown to a higher density than adherent conditions would allow. Adherent cells require a surface, such as tissue culture plastic or microcarrier, which may be coated with extracellular matrix (such as collagen and laminin) components to increase adhesion properties and provide other signals needed for growth and differentiation. Most cells derived from solid tissues are adherent. Another type of adherent culture is organotypic culture, which involves growing cells in a three-dimensional (3-D) environment as opposed to two-dimensional culture dishes. This 3D culture system is biochemically and physiologically more similar to in vivo tissue, but is technically challenging to maintain because of many factors (e.g. diffusion).

A pipette (sometimes called pipet) is a laboratory tool used to transfer a measured volume of liquid, generally as a media dispenser, in chemistry, biology, and medicine. Pipettes are available in a variety of designs and levels of accuracy and precision, ranging from simple single-piece glass pipettes to more complex adjustable or electronic pipettes. Many pipettes work by drawing up and dispensing liquid by establishing a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum. The precision of measurements varies substantially depending on the equipment.

Air displacement micropipettes

Air displacement pipette Single-Channel Pipettes designed to handle 1–5ml and 100–1000µl with locking systemA 5,000 μl (5 ml) pipette, with the volume to be transferred indicated. 500 means that the amount transferred is 5,000 μl.A 1,000 μl (1 ml) pipette, with the volume to be transferred indicated.A variety of pipette tips

Air displacement micropipettes are a type of adjustable micropipette that deliver a measured volume of liquid; depending on size, it could be between about 0.1 µl to 1,000 µl (1 ml). These pipettes require disposable tips that come in contact with the fluid. The four standard sizes of micropipettes correspond to four different disposable tip colors

These pipettes operate by piston-driven air displacement. A vacuum is generated by the vertical travel of a metal or ceramic piston within an airtight sleeve. As the piston moves upward, driven by the depression of the plunger, a vacuum is created in the space left vacant by the piston. The liquid around the tip moves into this vacuum (along with the air in the tip) and can then be transported and released as necessary. These pipettes are capable of being very precise and accurate. However, since they rely on air displacement, they are subject to inaccuracies caused by the changing environment, particularly temperature and user technique. For these reasons, this equipment must be carefully maintained and calibrated, and users must be trained to exercise correct and consistent technique.

The micropipette was invented and patented in 1960 by Dr. Heinrich Schnitger in Marburg, Germany. Afterwards, the co-founder of the biotechnology company Eppendorf, Dr. Heinrich Netheler, inherited the rights and initiated the global and general use of micropipettes in labs. In 1972, the adjustable micropipette was invented at the University of Wisconsin-Madison by several people, primarily Warren Gilson and Henry Lardy.

Types of air displacement pipettes include:

• adjustable or fixed
• volume handled
• Single-channel, multi-channel or repeater
• conical tips or cylindrical tips
• standard or locking
• manual or electronic
• manufacturer

Irrespective of brand or expense of pipette, every micropipette manufacturer recommends checking the calibration at least every six months, if used regularly. Companies in the drug or food industries are required to calibrate their pipettes quarterly (every three months). Schools which are conducting chemistry classes can have this process annually. Those studying forensics and research where a great deal of testing is commonplace will perform monthly calibrations.

Electronic pipette

To minimize the possible development of musculoskeletal disorders due to repetitive pipetting, electronic pipettes commonly replace the mechanical version.

Positive displacement pipette

These are similar to air displacement pipettes, but are less commonly used and are used to avoid contamination and for volatile or viscous substances at small volumes, such as DNA. The major difference is that the disposable tip is a microsyringe (plastic), composed of a capillary and a piston (movable inner part) which directly displaces the liquid.

Clothing technology includes production, materials, and developed and implemented improvements. Major changes in the manufacture and distribution of clothing are included in the timeline of clothing and textiles technology.

The usage of technology has drastically altered clothes and fashion in the contemporary age, from clothing in the ancient world through modernity. The manufacturing of commodities changed as a result of industrialization. In many countries, handcrafted goods have been substantially displaced by factory-produced commodities purchased on assembly lines in a consumer culture. Man-made fabrics like polyester, nylon, and vinyl, as well as features like zippers and velcro, are among the innovations.

Gore-Tex

Gore-Tex is a waterproof, breathable fabric membrane and registered trademark of W. L. Gore & Associates. Invented in 1969, Gore-Tex can repel liquid water while allowing water vapor to pass through and is designed to be a lightweight, waterproof fabric for all-weather use. It is composed of stretched polytetrafluoroethylene (PTFE), which is more commonly known by the generic trademark Teflon. The material is formally known as the generic term expanded PTFE (ePTFE).

Gore-Tex materials are typically based on thermo-mechanically expanded PTFE and other fluoropolymer products. They are used in a wide variety of applications such as high-performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants. However, Gore-Tex fabric is best known for its use in protective, yet breathable, rainwear.

The simplest sort of rain wear is a two layer sandwich. The outer layer is typically woven nylon or polyester and provides strength. The inner one is polyurethane (abbreviated: PU), and provides water resistance, at the cost of breathability.

Early Gore-Tex fabric replaced the inner layer of PU with a thin, porous fluoropolymer membrane (Teflon) coating that is bonded to a fabric. This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter). Each pore is approximately ¹⁄_20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the more volatile water vapour molecules to pass through.

The outer layer of Gore-Tex fabric is coated on the outside with a Durable Water Repellent (DWR) treatment. The DWR prevents the main outer layer from becoming wet, which would reduce the breathability of the whole fabric. However, the DWR is not responsible for the jacket being waterproof. Without the DWR, the outer layer would become soaked, there would be no breathability, and the wearer’s sweat being produced on the inside would fail to evaporate, leading to dampness there. This might give the appearance that the fabric is leaking, but it is not. Wear and cleaning will reduce the performance of Gore-Tex fabric by wearing away this Durable Water Repellent (DWR) treatment. The DWR can be reinvigorated by tumble drying the garment or ironing on a low setting.

Gore requires that all garments made from their material have taping over the seams, to eliminate leaks. Gore’s sister product, is similar to Gore-Tex in being windproof and breathable and it can stretch but it is not waterproof. The Gore naming system does not imply specific technology or material but instead specific set of performance characteristics.

Wearable technology, wearables, fashion technology, smartwear, tech togs, streetwear tech, skin electronics or fashion electronics are smart electronic devices (electronic device with micro-controllers) that are worn close to and/or on the surface of the skin, where they detect, analyze, and transmit information concerning e.g. body signals such as vital signs, and/or ambient data and which allow in some cases immediate biofeedback to the wearer

Wearable technology has a wide range of applications, which is growing as the area matures. With the popularity of the wristwatch and activity tracker, it has become a key feature in consumer electronics. The Apple Watch is a popular smartwatch on the market. Wearable technology is being used in navigation systems, sophisticated fabrics, and healthcare, in addition to commercial applications. Wearable technology must be validated for its dependability and security qualities before it can be used in critical applications.

Epidermal electronics is an emerging field of wearable technology, termed for their properties and behaviors comparable to those of the epidermis, or outermost layer of the skin.These wearables are mounted directly onto the skin to continuously monitor physiological and metabolic processes, both dermal and subdermal. Wireless capability is typically achieved through battery, Bluetooth or NFC, making these devices convenient and portable as a type of wearable technology. Currently, epidermal electronics are being developed in the fields of fitness and medical monitoring.

Current usage of epidermal technology is limited by existing fabrication processes. Its current application relies on various sophisticated fabrication techniques such as by lithography or by directly printing on a carrier substrate before attaching directly to the body. Research into printing epidermal electronics directly on the skin is currently available as a sole study source.

The significance of epidermal electronics involves their mechanical properties, which resemble those of skin. The skin can be modeled as bilayer, composed of an epidermis having Young’s Modulus (E) of 2-80 kPa and thickness of 0.3–3 mm and a dermis having E of 140-600 kPa and thickness of 0.05-1.5 mm. Together this bilayer responds plastically to tensile strains ≥ 30%, below which the skin’s surface stretches and wrinkles without deforming. Properties of epidermal electronics mirror those of skin to allow them to perform in this same way. Like skin, epidermal electronics are ultrathin (h < 100 μm), low-modulus (E ~ 70 kPa), and lightweight (<10 mg/cm²), enabling them to conform to the skin without applying strain. Conformal contact and proper adhesion enable the device to bend and stretch without delaminating, deforming or failing, thereby eliminating the challenges with conventional, bulky wearables, including measurement artifacts, hysteresis, and motion-induced irritation to the skin. With this inherent ability to take the shape of skin, epidermal electronics can accurately acquire data without altering the natural motion or behavior of skin. The thin, soft, flexible design of epidermal electronics resembles that of temporary tattoos laminated on the skin. Essentially, these devices are “mechanically invisible” to the wearer.

Epidermal electronics devices may adhere to the skin via van der Waals forces or elastomeric substrates. With only van der Waals forces, an epidermal device has the same thermal mass per unit area (150 mJ cm⁻² K⁻¹) as skin, when the skin’s thickness is <500 nm. Along with van der Waals forces, the low values of E and thickness are effective in maximizing adhesion because they prevent deformation-induced detachment due to tension or compression. Introducing an elastomeric substrate can improve adhesion but will raise the thermal mass per unit area slightly. Several materials have been studied to produce these skin-like properties, including photolithography patterned serpentine gold nanofilm and patterned doping of silicon nanomembranes.^[

Molecular Anatomy Reveals Evolutionary Relatio

The naturalist Carolus Linnaeus of the XVIII Gin of different types from a common ancestor. Biochemical research in the 20th century revealed the molecular anatomy of cells of different species, the sequences of monomeric subunits, and the three-dimensional structures of individual nucleic acids and proteins. Biochemists today have an enormously rich and growing body of evidence with which to analyze evolutionary relationships and refine the theory of evolution. The sequence of the genome (the complete genetic makeup of an organism) is completely determined for many eubacteria and for some archaebacteria; for the eukaryotic microorganisms Saccharomyces cere visiae and Plasmodium sp .; for Arabidopsis thaliana and rice plants; and for the multicellular animals Caenorhabditis elegans (a roundworm), Drosophila melanogaster (the fruit fly), mice, rats and Homo sapi ens (Sie). This list is periodically expanded to include additional sequences. With such sequences in hand, detailed and quantitative comparisons among species can provide deep insight into the evolutionary process. Thus far, the molecular phylogeny derived from gene sequences is consistent with, but in many cases more precise than, the classical phylogeny based on macroscopic structures. Although organisms have continuously diverged at the level of gross anatomy, at the molecular level the basic unity of life is readily apparent; molecular structures and mechanisms are remarkably similar from the simplest to the most complex organisms. These similarities are most easily seen at the level of sequences, either the DNA se quences that encode proteins or the protein sequences themselves.

When two genes share readily detectable sequence similarities (nucleotide sequence in DNA or amino acid sequence in the proteins they encode), their sequences

are said to be homologous and the proteins they encode are homologs. If two homologous genes occur in the same species, they are said to be paralogous and their protein products are paralogs. Paralogous genes are presumed to have been derived by gene duplication fol lowed by gradual changes in the sequences of both copies. Typically, paralogous proteins are similar not only in sequence but also in three-dimensional structure, although they commonly have acquired different func tions during their evolution.

Two homologous genes (or proteins) found in dif ferent species are said to be orthologous, and their pro tein products are orthologs. Orthologs are commonly found to have the same function in both organisms, and when a newly sequenced gene in one species is found to be strongly orthologous with a gene in another, this gene is presumed to encode a protein with the same function in both species. By this means, the function of gene products can be deduced from the genomic se quence, without any biochemical characterization of the gene product. An annotated genome includes, in ad dition to the DNA sequence itself, a description of the likely function of each gene product, deduced from com parisons with other genomic sequences and established protein functions. In principle, by identifying the path ways (sets of enzymes) encoded in a genome, we can deduce from the genomic sequence alone the organism’s

All living organisms fall into one of the three great groups (kingdoms or domains) that define three branches of evolution from a common ancestor (Fig. 14). For biochemical reasons, two large groups of prokaryotes can be distinguished: archaebacteria (from the Greek arche, “ori gin”) and eubacteria (again from the Greek eu, “true”). Eubacteria inhabit soil, surface water, and the tissue of other living or decaying organisms. Most of the well-studied bacteria, including Escherichia coli) are Eu bacteria. The newly discovered archaebacteria are less biochemically characterized; most live in extreme environments, salty lakes, hot springs, highly acidic moors, and the depths of the ocean. Available evidence suggests that archaebacteria and eubacteria diverged early in evolution, forming two separate domains, sometimes referred to as archaea and bacteria. All the eukaryotic organisms that make up the third domain, eukarya, evolved from the same branch from which the archaea arose; Therefore, archaebacteria are more closely related to eukaryotes.

Within the domains of Archaea and Bacteria are sub groups distinguished by the habitats in which they live. In aerobic habitats with a plentiful supply of oxygen, some resident organisms derive energy from the trans fer of electrons from fuel molecules to oxygen. Other environments are anaerobic, virtually devoid of oxy gen, and microorganisms adapted to these environments. obtain energy by transferring electrons to nitrate (form ing N₂), sulfate (forming H₂S), or CO₂ (forming CH₂). Many organisms that have evolved in anaerobic envi ronments are obligate anaerobes: they die when ex posed to oxygen.

We can classify organisms according to how they obtain the energy and carbon they need for synthesiz ing cellular material. There are two broad categories based on energy sources: pho totrophs (Greek trophe, “nourishment”) trap and use sunlight, and chemotrophs derive their energy from oxidation of a fuel. All chemotrophs require a source of organic nutrients; ey cannot fix CO₂ into organic com pounds. The phototrophs can be further divided into those that can obtain all needed carbon from CO₂ (au totrophs) and those that require organic nutrients (heterotrophs). No chemotroph can get its carbon atoms exclusively from CO₂ (that is, no chemotrophs are autotrophs), but the chemotrophs may be further classified according to a different criterion: whether the fuels they oxidize are inorganic (lithotrophs) or or ganic (organotrophs).

Biochemistry describes in molecular terms the struc tures, mechanisms, and chemical processes shared by all organisms and provides organizing principles that underlie life in all its diverse forms, principles we refer to collectively as the molecular logic of life. Although biochemistry provides important insights and practical applications in medicine, agriculture, nutrition, and industry, its ultimate concern is with the wonder of life itself.

Most known organisms fall within one of these four broad categories-autotrophs or heterotrophs among the photosynthesizers, lithotrophs or organotrophs among the chemical oxidizers. The prokaryotes have several gen eral modes of obtaining carbon and energy. Escherichia coli, for example, is a chemoorganoheterotroph; it re quires organic compounds from its environment as fuel and as a source of carbon. Cyanobacteria are photo lithoautotrophs; they use sunlight as an energy source and convert CO₂ into biomolecules. We humans, like E. coli, are chemoorganoheterotrophs.

The unity and diversity of organisms become apparent even at the cellular level. The smallest organisms consist of single cells and are microscopic. Larger, multicellular organisms contain many different types of cells, which vary in size, shape, and specialized function. Despite these obvious differences, all cells of the simplest and most complex organisms share certain fundamental properties, which can be seen at the biochemical level. Cells Are the Structural and Functional Units of All Living Organisms Cells of all kinds share certain structural features. The plasma membrane defines the periphery of the cell and separates its contents from the environment. It is made up of lipid and protein molecules that form a thin, tough, flexible hydrophobic barrier around the cell. The membrane is a barrier to the free passage of inorganic ions and most other charged or polar compounds. Transport proteins in the plasma membrane allow the passage of certain ions and molecules; Receptor proteins transmit signals into the cell; and membrane enzymes participate in several pathways. Since individual plasma membrane lipids and proteins are not covalently bound, the entire structure is remarkably flexible and allows for changes in cell size and shape. As a cell grows, newly formed lipid and protein molecules insert into its plasma membrane; Cell division creates two cells, each with its own membrane. This cell growth and division occurs without loss of membrane integrity.

The internal volume bounded by the plasma mem brane, the cytoplasm, is composed of an aqueous solution, the cytosol, and a variety of sus pended particles with specific functions. The cytosol is a highly concentrated solution containing enzymes and the RNA molecules that encode them; the components (amino acids and nucleotides) from which these macro molecules are assembled; hundreds of small organic molecules called metabolites, intermediates in biosyn thetic and degradative pathways; coenzymes, com pounds essential to many enzyme-catalyzed reactions; inorganic ions; and ribosomes, small particles (com posed of protein and RNA molecules) that are the sites of protein synthesis.

All cells have, for at least some part of their life, ei ther a nucleus or a nucleoid, in which the genomehe complete set of genes, composed of DNA-is stored and replicated. The nucleoid, in bacteria, is not sepa rated from the cytoplasm by a membrane; the nucleus, in higher organisms, consists of nuclear material en closed within a double membrane, the nuclear envelope. Cells with nuclear envelopes are called eukaryotes (Greek eu, “true,” and karyon, “nucleus”); those with out nuclear envelopes-bacterial cells are prokary otes (Greek pro, “before”).

Cellular Dimensions Are Limited by Oxygen Diffusion

Most cells are microscopic, invisible to the unaided eye. Animal and plant cells are typically 5 to 100 um in di ameter, and many bacteria are only 1 to 2 um long (see the inside back cover for information on units and their abbreviations). What limits the dimensions of a cell? The lower limit is probably set by the minimum number of each type of biomolecule required by the cell. The smallest cells, certain bacteria known as mycoplasmas, are 300 nm in diameter and have a volume of about 10-14 mL. A single bacterial ribosome is about 20 nm in its longest dimension, so a few ribosomes take up a sub stantial fraction of the volume in a mycoplasmal cell.

X-ray diffraction The spacing of atoms in a crystal lattice can be determined by measuring the locations and intensities of points created on photographic film by an X-ray beam of a particular wavelength after the beam has been diffracted. by the electrons of the atoms. For example, X-ray analysis of sodium chloride crystals shows that the Na and Cl ions are arranged in a simple cubic lattice. The distances between different types of atoms in complex organic molecules, including very large ones such as proteins, can also be analyzed using X-ray diffraction methods. However, the technique for analyzing crystals of complex molecules is much more complex than that of simple salt crystals. If the repeating pattern of the crystal is a protein-sized molecule, for example, the numerous atoms in the molecule result in thousands of diffraction points that need to be analyzed by computer. The process can be understood at an elementary level by considering how images are created in an optical microscope. Light from a point source is focused on an object. Light waves are scattered by the object and these scattered waves are recombined by a series of lenses to create a magnified image of the object. The smallest object whose structure can be determined with such a system, i.e. H. the resolution of the microscope is determined by the computer.

Wavelengths in the range of 400 to 700 nm Objects that are less than half the wavelength of the incident light cannot be resolved. To solve objects as small as proteins, we need to use X-rays with wavelengths in the range of 0.7 to 1.5 Å (0.07 to 0.15 nm). However, there are no lenses that can recombine X-rays into an image; instead, the pattern of the diffracted X-rays is collected directly and an image is reconstructed using mathematical techniques. The information content of X-ray crystallography depends on the degree of structural order of the sample. Some important structural parameters were obtained from the first studies of the diffraction patterns of fiber proteins, which are arranged in fairly regular arrangements in hair and wool. However, the ordered bundles made up of fiber proteins are not crystals, the molecules are lined up side by side, but not all are lined up in the same direction. The most detailed three-dimensional structural information of proteins requires a highly ordered protein crystal. Protein crystallization is an empirical science and the structures of many important proteins are not yet known simply because they have proven difficult to crystallize. Practitioners have compared making protein crystals to holding a stack of bowling balls together with cellophane tape. X-ray structure analysis is performed surgically in several steps. Once a crystal is obtained, it is placed in an X-ray beam between the X-ray source and a detector and a regular array of spots called reflection is generated. The spots are created by the diffracted x-ray beam, and each atom in a molecule makes a contribution to each spot. An electron-density map of the protein is reconstructed from the overall diffraction pattern of spots by using a mathematical technique called a Fourier transform. In effect, the computer acts as a “computational lens.” A model for the structure is then built that is consistent with the electron-density map.

It is a revolutionary method developed by Kary Mullis in the 1980s. PCR is based on the use of the ability of DNA polymerase to synthesize a new DNA strand that is complementary to the offered template strand. Since DNA polymerase can only add one nucleotide to an already existing 3`OH group, it needs a primer to which it can add the first nucleotide. This requirement allows the delineation of a specific region of the template sequence that the investigator wishes to amplify. At the end of the PCR reaction, the specific sequence accumulates in billions of copies (amplicons).

Components of PCR

DNA template: the DNA sample that contains the target sequence. At the beginning of the reaction, the original double-stranded DNA molecule is exposed to a high temperature to separate the strands from each other. DNA polymerase is a type of enzyme that synthesizes new DNA strands that are complementary to the target sequence. The first and most widely used of these enzymes is TaqDNA polymerase (from Thermis aquaticus), while PfuDNA polymerase (from Pyrococcus furiosus) is widely used due to its greater precision in DNA copying. Although these enzymes differ slightly, they both have two capabilities that make them suitable for PCR: 1) they can generate new DNA strands using a DNA template and primers, and 2) they are heat resistant, priming short single-stranded pieces. DNAs that are complementary to the target sequence. The polymerase begins at the end of the primer with the synthesis of new DNA. Nucleotides (dNTPs or deoxynucleotide triphosphates) individual units of the bases A, T, G and C, which are essentially “building blocks” for new DNA strands. Reverse transcription PCR) is a PCR that converts the RNA sample into cDNA using the enzyme.

Limitations of PCR and RTPCR The PCR reaction begins to make exponential copies of the target sequence. Back extrapolation to the initial amount of the target sequence contained in the sample is only possible during the exponential phase of the PCR reaction. Over time, due to inhibitors of the polymerase reaction found in the sample, limitation of the reagent, accumulation of pyrophosphate molecules, and self-adhesion of the accumulated product, the PCR reaction stops amplifying the target sequence to an exponential speed and a “plateau” occurs. Effect “on, making end point quantification of PCR products unreliable. This is the attribute of PCR that makes quantitative real-time RTPCR so necessary.

Application

PCR allows the isolation of DNA fragments from genomic DNA by selective amplification of a specific DNA region. This use of PCR expands many pathways, such as the generation of hybridization probes for Southern or Northern hybridization and DNA cloning, that require larger amounts of DNA representing a specific region of DNA. PCR provides these techniques with large amounts of pure DNA and allows DNA samples to be analyzed even from very small amounts of starting material. Other uses of PCR include DNA sequencing to determine unknown PCR amplified sequences in which one of the amplification primers can be used in Sanger sequencing, isolation of a DNA sequence to accelerate recombinant DNA technologies that allow the insertion of a DNA sequence into a plasmid, phage or cosmid (depending on size) or the genetic material of another organism. Bacterial colonies (such as E. coli) can be quickly screened for correct DNA vector constructs by PCR. [20] PCR can also be used for genetic fingerprinting; forensic technique used to identify a person or organism by comparing experimental DNA using various PCR-based methods. Electrophoresis of PCR amplified DNA fragments: Father Child Mother The child has inherited some, but not all, of the fingerprints of each of her parents, giving them a new and unique fingerprint. Some PCR fingerprinting methods are highly discriminatory and can be used to identify genetic relationships between individuals, such as parents and children or between siblings, and are used in paternity

Pesticides are the gathering of synthetics or substance plans utilized in horticulture for shielding yields or crop items from the danger of nuisances, creepy crawlies, spices, weeds and organism etc. A significant number of these agrochemicals are accounted for to be cancer-causing in lab creatures. Epidemiological confirmations of cancer-causing impacts of a portion of the pesticides in creatures are additionally known. The pesticides are ordered into four gatherings viz., organochlorines, organophosphates, carbamates and various sort.

About forty five organochlorine, eight organophosphorus and similar number of cabamate pesticides have been reported to be carcinogenic experimental animals. The important organochlorines with sufficient or limited evidence for carcinogenicity to experimental animal as per the Intentional Agency for Research on Cancer (IARC) evaluations are captan, carbon tetrachloride, chlorobenzilate, chlardane, chlordecone (kepone), chloroform, chlorothalonil, diallate (Avadox), 1,2-dibromo-3-chloro-propane, 1,2-dichloroethane, (edicofol), heptachlor and heptachlor epoxide, hexachlorobenzene, hexachlorobutadine, hexachloro cyclohexane, hexachloroethane, mirex, 1,2,2-tetrachloroethane, tetrachlorvinphos and toxaphene.

The non-judicious use of pesticides (improper selection, repeated application, substandard product, excessive dosage etc.) has been responsible for various ills. Most of these problems can be overcome through a proper pesticide selection. application, post-application care and monitoring to identify undesirable effects, corrective measures to overcome the defects, etc., the aspects which constitute the term pesticide management. During the Year 1994-1995, the global pesticide.

market stood at 27.8 million U.S. Dollars. It showed an increase of 10.1 per cent over the previous years. Pesticide sales across Western Europe revealed a rise of 12 per cent being the largest in France, Italy, Germany, and UK. The ever increasing use of different types of pesticides the world over has been associated with serious environmental problems. Still the fact remains that pesticides are basically poisonous it is also to be acknowledged that the global poverty and illiteracy levels are not likey to improve in the near future, thus ruling out the possibility of a judicious pesticide usage in the forseable future. The harmful effects of pesticides may thus be investable.

Harmful effects of pesticides: The salient harmful effects of pesticides include the contamination of the environment and food, feed and fibre, disruption of non-target organisms, pest resistance, pest resurgence, and so on. These defects have to be overcome while planning pesticide management strategies. Insecticide resistance occurs as a result of inappropriate and large scale use of pesticides particularly at sub-lethal doses, repeated application of the same pesticide or similar group of pesticides over a period of time as well as under dosing due to substandard pesticidal formulations. The situations, besides bringing drastic changes in the pest complex and crop environment, has culminated in outbreaks of several secondary pests. Even some minor ones have assumed the status of major pests.

A statistically significant increase in the pest population as a consequence of pesticide use, in spite of a good initial kill at the time of treatment, was called as “resurgence” or flare back. Evidences were also forthcoming that insecticide residues in host plants and insecticides applied at sub lethal doses simulated the reproduction and survival of phytophagous insects and mites, leading to pest resurgence.

In Asia the resurgence of brown plant hopper following insecticide application was reported in rice. In cotton, the use of synthetic pyrethroides to control boll worm enhanced the population of white fly, Bemisia tabaci. The key examples of pest resurgence in India are listed in Table 1. When insecticides or other pesticides are employed, the poison not only destroys the pest, but also has a serious impact on its natural enemies. In some cases, the destroyed natural enemies are important in controlling certain other pests also. When these natural enemies are eliminated; it may result in outbreak of pests that were previously not a problem in the target crop.

science is an attitude. or a way of looking at things, which arose out of man’s intellectual curiosity. The first humanoid creature that stood on a seashore and observed that the water level rose and fell with the regularity and asked himself what caused this was exhibiting a basic mark of a scientist. As he further noted the changing phases of the moon and correlated tidal and lunar cycles, his scientific expression became more refined, for he was systematizing his data and recognizing relationship even though he could not, at that time, know the casual aspects of the phenomena. throughout the history curiosity and the desire to know have been more intuitive and more sharply developed in some individual than others. some are gifted with the power to question. whereas, some are behind the logical reasoning of everything.

To us, Then, science may be defined as ordered knowledge of natural phenomena and the rational study of the relationship between the concept in which those phenomena are expressed

Wikipedia contributors. (2020, December 12). William Cecil Dampier. In Wikipedia, The Free Encyclopedia. Retrieved 18:05, September 24, 2021, from https://en.wikipedia.org/w/index.php?title=William_Cecil_Dampier&oldid=993745527

There are plethora of faces of science but as for a basic human it is a study of all three states of matter and it products. Science is, in basic sense, a search of truth and its meaning an has a foundation in the belief that this is a worth-while human endeavor.

Our search for understanding of the universe, or science, is based of three assumption, each rather simple but nonetheless broad in its influence on views of nature. the first assumption is that natural phenomena are amenable to understanding using scientific methods. the second is that there is orderliness in nature, that a natural process operate according to general principle, so that when the general principles are understood, precautions can be made about natural events such as tidal cycle. finally, the third assumption is that there exists a cause foe each observable effect.

From over many centuries humankind has always been fascinated and devastated by events of nature. Humankind lives in a big blue planet that is mostly water. The one in billions of planet which support life. Therefore it our basic right and necessity to understand how the universe works, how it effects our daily life. There are some people within the billions that have the power and desire to seek the knowledge of everything around them, thus ” scientist”.

For one to become a scientist the basic requirement is being able to question and resolve them. Asking the question to self and have a thirst to find answers. If you live near a university or a research center and shop in nearby markets, you probably cannot distinguish a scientist from any other man. The typical scientist is not the white-coated, long hair, evil-looking or absent minded which is basically shown in movies or cartoons. They are likely to be father or mother with whom you have met randomly. Intellectually, the scientist is neither more nor less genius than any other intelligent man seeking to inquire onto the nature of things. He possesses a high degree of intellectual curiosity about his world and desire to share his finding through publication of results in magazines and journals. Like the mountain climber who wants to scale a peak “just because its there”, the scientist studies a mold, a new chemical, a cell, plant, animals and other mysteries just because they are unknown. Scientist may be said to be pursuing Pure science.