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| Biosolution |
| Biosolutions is a repository of Biological animations and lectures. The aim of site is create knowledge base among the students community |
| Language: English |
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| Total Unique Visitors: 1326102 |
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| Cell Signals lecture |
| 2008-05-10 22:50:00 |
Part 1Part 2Part 3Related Links:BioSolutions: Cell Signal AnimationBioSolutions: Signal TransductionBioSolutions: Lecture on Stem Cells and the End of Aging
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| Genetic Transfer |
| 2008-05-10 01:19:00 |
Genetic Transfer part1Genetic Transfer part2Genetic Transfer part 3Genetic Transfer part 4Related Links:BioSolutions: TranscriptionBioSolutions: MutationBioSolutions: Gene Therapy for Heart failureBioSolutions: Comparative GenomicsBioSolutions: mRna Spilicing
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| First Human Gene Therapy |
| 2008-05-08 21:30:00 |
On September 14, 1990 at the U.S. National Institutes of Health W. French Anderson, M.D., and his colleagues R. Michael Blaese, M.D., C. Bouzaid, M.D., and Kenneth Culver, M.D., performed the first approved gene therapy procedure on four-year old Ashanthi DeSilva. Born with a rare genetic disease called severe combined immunodeficiency (SCID), she lacked a healthy immune system, and was vulnerable to every passing germ or infection. Children with this illness usually develop overwhelming infections and rarely survive to adulthood; a common childhood illness like chickenpox is life-threatening. Ashanthi led a cloistered existence -- avoiding contact with people outside her family, remaining in the sterile environment of her ...
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| Chromosomes |
| 2008-05-07 21:30:00 |
Chromosomes are organized structures of DNA and proteins that are found in cells. A chromosome is a continuous piece of DNA, which contains many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being stained very strongly by some dyes.Chromosomes vary extensively between different organisms. The DNA molecule may be circular or linear, and can contain anything from tens of kilobase pairs to hundreds of megabase pairs. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller ci...
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| Conotoxin |
| 2008-05-06 07:48:00 |
Conotoxin is a neurotoxic peptides .It is isolated from the venom of marine cone snail,genus Conus,Its consist of 10 to 30 aminoacid residues,Typically have one or more dilsulfde bonds,Conotoxins have a variety of mechanisms of action like ion channels.Types and biological activities of conotoxinsThe number of conotoxins whose activities have been determined so far is five, and they are called the α(alpha)-, δ(delta)-, κ(kappa)-, μ(mu)-, and ω(omega)- types. Each of the five types of conotoxins attacks a different target * α-conotoxin inhibits acetylcholine receptors at nerves and muscles. * δ-conotoxin inhibits the inactivation of voltage-dependent sodium channels. * κ-conotoxin inhibits potassium channels. * μ-conotoxin inhibits voltage-dependent sodium channels in muscl...
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| Inflammatory Response |
| 2008-05-04 23:30:00 |
The inflammatory response must be actively terminated when no longer needed to prevent unnecessary "bystander" damage to tissues. Failure to do so results in chronic inflammation, cellular destruction, and attempts to heal the inflamed tissue. One intrinsic mechanism employed to terminate inflammation is the short half-life of inflammatory mediators in vivo. They have a limited time frame to affect their target before breaking down into non-functional components, therefore constant inflammatory stimulation is needed to propagate their effects.Ihe Inflammatory Response can be triggered by invasion of bacteria,Substances released by bacteiria by damaged cells accumulate in tissue small blood vessels become more premeable and plasma fluids and proteins leakout,plasma protein attack bacteria a...
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| Nanobots replacing neurons |
| 2008-05-04 00:30:00 |
Nanorobotics is the technology of creating machines or robots at or close to the microscopic scale of a nanometres (10-9 metres). More specifically, nanorobotics refers to the still largely hypothetical nanotechnology engineering discipline of designing and building nanorobots. Nanorobots (nanobots, nanoids or nanites) would be typically devices ranging in size from 0.1-10 micrometers and constructed of nanoscale or molecular components. As no artificial non-biological nanorobots have so far been created, they remain a hypothetical concept at this time.Another definition sometimes used is a robot which allows precision interactions with nanoscale objects, or can manipulate with nanoscale resolution. Following this definition even a large apparatus such as an atomic force microscope can be ...
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| Nephron Animation |
| 2008-05-02 22:48:00 |
A nephron (from Greek νεφρός (nephros) meaning "kidney") is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates blood volume and pressure, controls levels of electrolytes and metabolites, and regulates blood pH. Its functions are vital to life and are regulated by the endocrine system by hormones such as antidiuretic hormone, aldosterone, and parathyroid hormone.Types of nephronsTwo general classes of nephrons are cortical nephrons and juxtamedullary nephrons, both of which are classified according to the location of their associated renal corpu...
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| Steroid Hormone Animation |
| 2008-05-01 22:30:00 |
Steroid hormones are steroids which act as hormones. Mammalian steroid hormones can be grouped into five groups by the receptors to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestagens. Vitamin D derivatives are a sixth closely related hormone system with homologous receptors, though technically sterols rather than steroids.The natural steroid hormones are generally synthesized from cholesterol in the gonads and adrenal glands. These forms of hormones are lipids. They can enter the cell membrane quite easily and enter right into the nuclei. Steroid hormones are generally carried in the blood bound to specific carrier proteins such as sex hormone binding globulin or corticosteroid binding globulin. Further conversion...
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| p53 Cellular tumor antigen p53 |
| 2008-04-30 23:30:00 |
p53, also known as protein 53 (TP53), is a transcription factor that regulates the cell cycle and hence functions as a tumor suppressor. It is important in multicellular organisms as it helps to suppress cancer. p53 has been described as "the guardian of the genome," "the guardian angel gene," or the "master watchman," referring to its role in conserving stability by preventing genome mutation.The name p53 is in reference to its apparent molecular mass: it runs as a 53-kilodalton (kDa) protein on SDS-PAGE. But different ways of measuring molecular mass can produce different results. Based on calculations from its amino acid residues, p53's mass is actually only 43.7 kilodaltons. This difference is due to the high number of amino-acid proline residues in the p53 protein which slow p53's mig...
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| Transurethral Resection of Prostate (TURP) |
| 2008-04-30 07:42:00 |
Transurethral resection of the prostate (also known as TURP, plural TURPs and as a transurethral prostatic resection TUPR) is a urological operation. It is used to treat benign prostatic hyperplasia (BPH). As the name indicates, it is performed by visualising the prostate through the urethra and removing tissue by electrocautery or sharp dissection. This is considered the most effective treatment for BPH. This procedure is done with spinal or general anesthetic. A large triple lumen catheter is inserted through the urethra to irrigate and drain the bladder after the surgical procedure is complete. Outcome is considered excellent for 80-90% of BPH patients. As with all invasive procedures, the patient should first discuss medications they are taking with their doctor, most especially blood ...
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| Gold Nanoparticles In Cancer Cell Detection |
| 2008-04-30 01:19:00 |
Binding gold nanoparticles to a specific antibody for cancer cells could make cancer detection much easier, suggests research at the Georgia Institute of Technology and the University of California at San Francisco (UCSF). The report is published in the May 11, 2005 edition of the journal Nano Letters.“Gold nanoparticles are very good at scattering and absorbing light,” said Mostafa El-Sayed, director of the Laser Dyanamics Laboratory and chemistry professor at Georgia Tech. “We wanted to see if we could harness that scattering property in a living cell to make cancer detection easier. So far, the results are extremely promising.”Many cancer cells have a protein, known as Epidermal Gro...
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| NER pathway |
| 2008-04-28 09:51:00 |
Nucleotide excision repair is a DNA repair mechanism. DNA constantly requires repair due to damage that can occur to bases from a vast variety of sources including chemicals but also ultraviolet (UV) light from the sun. Nucleotide excision repair (NER) is a particularly important mechanism by which the cell can prevent unwanted mutations by removing the vast majority of UV-induced DNA damage (mostly in the form of thymine dimers and 6-4-photoproducts). The importance of this repair mechanism is evidenced by the severe human diseases that result from in-born genetic mutations of NER proteins including Xeroderma pigmentosum and Cockayne's syndrome. While the base excision repair machinery can recognize specific lesions in the DNA and can correct only damaged bases that can be removed by a sp...
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| Mast cell Animation |
| 2008-04-28 00:10:00 |
A mast cell (or mastocyte) is a resident cell of several types of tissues and contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens.Mast cells were first described by Paul Ehrlich in his 1878 doctoral thesis on the basis of their unique staining characteristics and large granules. These granules also led him to the mistaken belief that they existed to nourish the surrounding tissue, and he named them "mastzellen," a German term, meaning "feeding-cells." Nowadays, they are considered part of the immune system. Mast cells are very similar to basophil granulocytes (a class o...
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| Pulmonary Embolism |
| 2008-04-24 23:00:00 |
Pulmonary embolism (PE) is a blockage of the pulmonary artery (or one of its branches), usually when a venous thrombus (blood clot from a vein), becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. This process is termed thromboembolism.Symptoms may include difficulty breathing, pain in the chest during breathing, and in more severe cases collapse, circulatory instability and sudden death. Treatment, usually, is with anticoagulant medication, such as heparin and warfarin, and rarely (in severe cases) with thrombolysis or surgery. In other, rarer forms of pulmonary embolism, material other than a blood clot is responsible; this may include fat or bone (usually in association with significant trauma), air (often when diving), clumped tu...
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| DNA chips and Microarrays |
| 2008-04-23 21:04:00 |
A DNA microarray is an arrayed series of microscopic spots of DNA oligonucleotides, called features, where each feature contains picomoles of a specific unique sequence, such as a stretch of a gene sequence, which is used to measure the relative abundance of a sequence between samples, either differentially labelled or on different microarrays.These molecules are the used as probes to which only the correct target sequence will hybridise under high-stringency conditions; where the target is the labelled mix of either RNA or DNA to be analysed, in the majority of cases with a fluorophore-based detection system.In "traditional" microarrays the probes are bound to a solid surface by covalent attachment to a chemical matrix. The solid surface can either be glass ...
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| Beta cells (Insulin Production) |
| 2008-04-21 20:45:00 |
Beta cells (beta-cells, β-cells) are a type of cell in the pancreas in areas called the islets of Langerhans. They make up 65-80% of the cells in the islets.In mammals, insulin is synthesized in the pancreas within the beta cells (β-cells) of the islets of Langerhans. One to three million islets of Langerhans (pancreatic islets) form the endocrine part of the pancreas, which is primarily an exocrine gland. The endocrine portion only accounts for 2% of the total mass of the pancreas. Within the islets of Langerhans, beta cells constitute 60–80% of all the cells.In beta cells, insulin is synthesized from the proinsulin precursor molecule by the action of proteolytic enzymes, known as prohormone convertases (PC1 and PC2), as well as the exoprotease carboxy...
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| Total Hip Replacement Surgery |
| 2008-04-20 22:00:00 |
Hip replacement, also hip arthroplasty, is a surgical procedure in which the hip joint is replaced by a prosthetic implant. Such joint replacement orthopaedic surgery generally is conducted to relieve arthritis pain or fix severe physical joint damage as part of the hip fracture treatment.There are several different incisions, defined by their relation to the gluteus medius. The approaches are posterior (Moore), lateral (Hardinge or Liverpool), antero-lateral (Watson-Jones), anterior (Smith-Petersen) and greater trochanter osteotomy. There is no compelling evidence in the literature for any particular approach, but consensus of professional opinion favours either modified anterio-lateral (Hardinge) or posterior a...
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| T helper cell lymphocyte |
| 2008-04-18 09:00:00 |
T helper cells (also known as effector T cells or Th cells) are a sub-group of lymphocytes (a type of white blood cell or leukocyte) that plays an important role in establishing and maximizing the capabilities of the immune system. These cells are unusual in that they have no cytotoxic or phagocytic activity; they cannot kill infected host (also known as somatic) cells or pathogens, and without other immune cells they would usually be considered useless against an infection. Th cells are involved in activating and directing other immune cells, and are particularly important in the immune system. They are essential in determining B cell antibody class switching, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phag...
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| Circulatory System |
| 2008-04-17 09:02:00 |
The circulatory system is an organ system that moves nutrients, gases, and wastes to and from cells, helps fight diseases and helps stabilize body temperature and pH to maintain homeostasis. This system may be seen strictly as a blood distribution network, but some consider the circulatory system as composed of the cardiovascular system, which distributes blood, and the lymphatic system, which distributes lymph. While humans, as well as other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The most primitive animal phyla lack circulatory systems. The lymphatic system, on the other hand, is an open system.The ma...
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| SDS-Polyacrylamide Gel Electrophoresis |
| 2008-04-16 07:39:00 |
SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis, is a technique used in biochemistry, genetics and molecular biology to separate proteins according to their electrophoretic mobility (a function of length of polypeptide chain or molecular weight as well as higher order protein folding, posttranslational modifications and other factors).ProcedureThe solution of proteins to be analyzed is first mixed with SDS, an anionic detergent which denatures secondary and non–disulfide–linked tertiary structures, and applies a negative charge to each protein in proportion to its mass. Without SDS, different proteins with similar molecular weights would migrate differently due to differences in mass charge ratio, as each protein has an isoelectric point and molecular weight particu...
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| Central dogma Lecture |
| 2008-04-15 08:19:00 |
The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970:The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.The dogma is a framework for understanding the transfer of sequence information between sequential information-carrying biopolymers, in the most common or general case, in living organisms. There are 3 major classes of such biopolymers: DNA and RNA (both nucleic acids), and protein. There are 3×3 = 9 conceivable direct transfers of information that can occur between these. The dogma classes these into ...
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| Schizophrenia |
| 2008-04-15 05:45:00 |
Schizophrenia is a chronic, severe, and disabling brain disorder that has been recognized throughout recorded history. It affects about 1 percent of Americans.People with schizophrenia may hear voices other people don't hear or they may believe that others are reading their minds, controlling their thoughts, or plotting to harm them. These experiences are terrifying and can cause fearfulness, withdrawal, or extreme agitation. People with schizophrenia may not make sense when they talk, may sit for hours without moving or talking much, or may seem perfectly fine until they talk about what they are really thinking. Because many people with schizophrenia have difficulty holding a job or caring for themselves, the burden on their families and society is significant as well.Available treatments...
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| Plasmid Cloning animation |
| 2008-04-14 05:30:00 |
Process by which a plasmid is used to import recombinant DNA into a host cell for cloning.Many diseases are caused by gene alterations. Our understanding of genetic diseases was greatly increased by information gained from DNA cloning. In DNA cloning, a DNA fragment that contains a gene of interest is inserted into a cloning vector or plasmid.The plasmid carrying genes for antibiotic resistance, and a DNA strand, which contains the gene of interest, are both cut with the same restriction endonuclease. The plasmid is opened up and the gene is freed from its parent DNA strand. They have complementary "sticky ends." The opened plasmid and the freed gene are mixed with DNA ligase, which reforms the two pieces as recombinant DNA.This recombinant DNA stew is allowed to transform a bacterial cult...
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| Vascular Access Port |
| 2008-04-13 12:20:00 |
A vascular access procedure involves the insertion of a catheter into a blood vessel to provide a painless way of drawing blood or delivering drugs and nutrients into a patient's bloodstream over a period of weeks, months or even years.A simple intravenous (IV) line is effective for short-term use, but may lose its function long-term. When an IV line is necessary for a longer period of time and/or a more secure venous access is necessary, a special catheter, called a central access catheter, or a similar device is placed inside a major blood vessel either temporarily (days) or long-term (weeks to years) so that it can be easily and repeatedly accessed over a desired period of time.In a vascular access procedure, a special catheter is inserted inside a major vein (generally in one of the la...
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| Single Nucleotide Polymorphism (SNP) Animation |
| 2008-04-12 01:26:00 |
A single nucleotide polymorphism (SNP, pronounced snip), is a DNA sequence variation occurring when a single nucleotide - A, T, C, or G - in the genome (or other shared sequence) differs between members of a species (or between paired chromosomes in an individual). For example, two sequenced DNA fragments from different individuals, AAGCCTA to AAGCTTA, contain a difference in a single nucleotide. In this case we say that there are two alleles : C and T. Almost all common SNPs have only two alleles. For a variation to be considered a SNP, it must occur in at least 1% of the population.Within a population, SNPs can be assigned a minor allele frequency - the lowest allele frequency at a locus that is observed in a particular population. This is simply the les...
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| DNA Replication Lecture |
| 2008-04-10 22:22:00 |
DNA replication is the process of copying a double-stranded DNA molecule to form two double-stranded molecules.[1][2] The process of DNA replication is a fundamental process used by all living organisms as it is the basis for biological inheritance. As each DNA strand holds the same genetic information, both strands can serve as templates for the reproduction of the opposite strand. The template strand is preserved in its entirety and the new strand is assembled from nucleotides — this process is called "semiconservative replication". The resulting double-stranded DNA molecules are identical; proofreading and error-checking mechanisms exist to ensure near perfect fidelity.DNA Replication DNA Replication 2 Dna replication 3 In a cell, DNA replication must ha...
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| DNA Repair |
| 2008-04-09 22:04:00 |
DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day.Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. Consequently, the DNA repair process is constantly active as it responds to damage in t...
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| Trinucleotide Repeat Disorders |
| 2008-04-08 21:11:00 |
Trinucleotide repeat disorders (also known as trinucleotide repeat expansion disorders, triplet repeat expansion disorders or codon reiteration disorders) are a set of genetic disorders caused by trinucleotide repeats in certain genes exceeding the normal, stable, threshold, which differs per gene. The mutation is a subset of unstable microsatellite repeats that occur throughout all genomic sequences. If the repeat is present in a healthy gene, a dynamic mutation may increase the repeat count and result in a defective gene.Trinucleotide repeat disorders are classified as a type of Non-Mendelian inheritanceTri Nucleotide RepeatSince the early 90’s, a new class of molecular disease has been characterized based upon the presence of unstable and abnormal ...
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| Chromosomal Crossing Over |
| 2008-04-07 22:12:00 |
Chromosomal crossover (or crossing over) is the process by which two chromosomes pair up and exchange sections of their DNA. This often occurs during prophase 1 of meiosis in a process called synapsis. Synapsis begins before the synaptonemal complex develops, and is not completed until near the end of prophase 1. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome. The result of this process is an exchange of genes, called genetic recombination. Chromosomal crossovers also occur in asexual organisms and in somatic cells, since they are important in some forms of DNA repair. A double crossing overRecombination involves the breakage and rejoining of parental chromosomesCrossing over was first described, in theory, by Thomas ...
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| Urinary Tract Infections (UTI) |
| 2008-04-07 09:00:00 |
A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract. Although urine contains a variety of fluids, salts, and waste products, it usually does not have bacteria in it. When bacteria get into the bladder or kidney and multiply in the urine, they cause a UTI. The most common type of UTI is a bladder infection which is also often called cystitis. Another kind of UTI is a kidney infection, known as pyelonephritis, and is much more serious. Although they cause discomfort, urinary tract infections can usually be quickly and easily treated when the patient sees a doctor promptly. Symptoms & signsFor bladder infectionsFrequent urination along with the feeling of having to urinate even though there may be very little urine to pass.Nocturia: Need to ...
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| Blood Vascular System |
| 2008-04-04 05:51:00 |
The blood and lymphatic vascular systems are classified as specialized connective tissue.The main functions of the blood are to transport oxygen, nutrients and hormones to the tissues and to collect the waste products (carbon dioxide and waste metabolites) for removal from the body via the excretory system. The cardiovascular system consists of the:Heart (muscular pump)Pulmonary circulation (system of blood vessels to and from the lungs)Systemic circulation (system of blood vessels bringing blood to and from all the other organs of the body).Arteries are classified into two main groups:Conducting (Elastic Arteries).These are large arteries closest to the heart (aorta, renal artery) with very high blood pressure and flow (32...
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| MacroPhage in Immune system |
| 2008-04-03 09:22:00 |
Macrophages are cells within the tissues that originate from specific white blood cells called monocytes. Monocytes and macrophages are phagocytes, acting in both non-specific defense (or innate immunity) as well as specific defence (or cell-mediated immunity) of vertebrate animals. Their role is to phagocytose (engulf and then digest) cellular debris and pathogens either as stationary or mobile cells, and to stimulate lymphocytes and other immune cells to respond to the pathogen.Macrophages are versatile cells that play many roles. As scavengers, they rid the body of worn-out cells and other debris. They are foremost among the cells that "present" antigen; a crucial role in initiating an immune response. As secretory cells, monocytes and macrophages are ...
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| Benign Fibroadenoma Tumors |
| 2008-04-03 05:20:00 |
Definition Fibroadenoma of the breast is a benign (noncancerous) tumor.Causes, incidence, and risk factors Fibroadenoma is the most common benign tumor of the breast and the most common breast tumor in women less than 30 years of age. Fibroadenomas are usually found as solitary lumps, but about 10-15% of women have multiple lumps that may affect both breasts.Black women tend to develop fibroadenomas more frequently and at an earlier age than white women. The cause of fibroadenoma is not known.Symptoms Lumps may be moveable, painless, firm, or rubbery, with well-defined bordersMay grow in size, especially during pregnancyOften get smaller after menopause (if not taking hormones)Signs and tests The following may be performed to gain information about a breast lump:Physical examination...
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| Brain |
| 2008-04-02 04:30:00 |
Brainstem - The lower extension of the brain where it connects to the spinal cord. Neurological functions located in the brainstem include those necessary for survival (breathing, digestion, heart rate, blood pressure) and for arousal (being awake and alert).Most of the cranial nerves come from the brainstem. The brainstem is the pathway for all fiber tracts passing up and down from peripheral nerves and spinal cord to the highest parts of the brain.Cerebellum - The portion of the brain (located at the back) which helps coordinate movement (balance and muscle coordination). Damage may result in ataxia which is a problem of muscle coordination. This can interfere with a person's ability to walk, talk, eat, and to perform other self care tasks.Frontal Lobe - ...
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| Photosynthesis |
| 2008-04-01 03:30:00 |
Photosynthesis is the conversion of light energy into chemical energy by living organisms. The raw materials are carbon dioxide and water; the energy source is sunlight; and the end-products are oxygen and (energy rich) carbohydrates, for example sucrose, glucose and starch. This process is arguably the most important biochemical pathway,[1] since nearly all life either directly or indirectly depends on it. It is a complex process occurring in higher plants, phytoplankton, algae, as well as bacteria such as cyanobacteria. Photosynthetic organisms are also referred to as photoautotrophs.Photosynthesis uses light energy and carbon dioxide to make triose phospates (G3P). G3P is generally considered the prime end-product of photosynthesis. It can be used as an immediate food nutrient, or combi...
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| T cell lymphocyte |
| 2008-03-31 00:42:00 |
T cells belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and NK cells by the presence of a special receptor on their cell surface called the T cell receptor (TCR). The abbreviation T, in T cell, stands for thymus, since it is the principal organ in the T cell's development.Several different subsets of T cells have been described, each with a distinct function.Helper T cells (TH cells) are the "middlemen" of the adaptive immune system. Once activated, they divide rapidly and secrete small proteins called cytokines that regulate or "help" the immune response. Depending on the cytokine signals received, these cells differentiate ...
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| DNA sequencing |
| 2008-03-28 21:44:00 |
DNA sequencing encompasses biochemical methods for determining the order of the nucleotide bases, adenine, guanine, cytosine, and thymine, in a DNA oligonucleotide. The sequence of DNA constitutes the heritable genetic information in nuclei, plasmids, mitochondria, and chloroplasts that forms the basis for the developmental programs of all living organisms. Determining the DNA sequence is therefore useful in basic research studying fundamental biological processes, as well as in applied fields such as diagnostic or forensic research. The advent of DNA sequencing has significantly accelerated biological research and discovery. The rapid speed of sequencing attainable with modern DNA sequencing technology has been instrumental in the large-scale sequencing of t...
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| Chromosomal Inversion |
| 2008-03-27 20:47:00 |
An inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end. An inversion occurs when a single chromosome undergoes breakage and rearrangement within itself. Inversions are of two types: paracentric and pericentric.Paracentric inversions do not include the centromere and both breaks occur in one arm of the chromosome. Pericentric inversions include the centromere and there is a break point in each arm.Cytogenetic techniques may be able to detect inversions, or inversions may be inferred from genetic analysis. Nevertheless, in most species small inversions go undetected. In insects with polytene chromosomes, for example Drosophila, preparations of larval salivary gland chromosomes allow inversions to be seen when they are heterozygous. This useful ch...
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| Gene mutation |
| 2008-03-26 20:37:00 |
Mutations are changes to the nucleotide sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can occur deliberately under cellular control during processes such as hypermutation. In multicellular organisms, mutations can be subdivided into germ line mutations, which can be passed on to descendants, and somatic mutations, which are not transmitted to descendants in animals. Plants sometimes can transmit somatic mutations to their descendants asexually or sexually (in case when flower buds develop in somatically mutated part of plant). A new mutation that was ...
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