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Category:Developmental Biology

Category:Developmental biology

Developmental biology is the study of the process by which organisms grow and develop. Originally termed embryology, today developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis," which is the process that gives rise to tissues, organs and anatomy. The related field of evolutionary developmental biology was formed largely in the 1990s and is a synthesis of findings from molecular developmental biology and evolutionary biology which considers the diversity of organismal form in an evolutionary context. developmental biology ko:분류:발생생물학 ja:Category:発生生物学

Cell growth

The term cell growth is used in two different ways in biology. When used in the context of reproduction of living cells the phrase "cell growth" is shorthand for the idea of "growth in cell numbers by means of cell reproduction." During cell reproduction one cell (the "parental" cell) divides to produce daughter cells. In other contexts, "cell growth" refers to increases in cell size.

Cell size

Many cells never have a large increase in size after they are first formed from a parental cell. Typical stem cells reproduce, double in size, then reproduce again. Most Cytosolic contents such as the endomembrane system and the cytoplasm easily scale to larger sizes in larger cells. If a cell becomes too large, the normal cellular amount of DNA may not be adequate to keep the cell supplied with RNA. Large cells often replicate their chromosomes to an abnormally high copy number or become multinucleated. Large cells that are primarily for nutrient storage can have a smooth surface membrane, but metabolically active large cells often have some sort of folding of the cell surface membrane in order to increase the surface area available for transport functions.

Yeast cell size regulation

The relationship between cell size and cell division has been extensively studied in yeast. For some cells, there is a mechanism by which cell division is not initiated until a cell has reached a certain size. If the nutrient supply is restricted (after time t = 2 in the diagram, below) and the rate of increase in cell size is slowed, the time period between cell divisions is increased. Yeast cell size mutants were isolated that begin cell division before reaching the normal size (wee mutants). The Wee1 protein is a tyrosine kinase. It normally phosphorylates the Cdc2 cell cycle regulatory protein on a tyrosine residue. This covalent modification of the molecular structure of Cdc2 inhibits the enzymatic activity of Cdc2 and prevents cell division. In Wee1 mutants, there is less Wee1 activity and Cdc2 becomes active in smaller cells, causing cell division before the yeast cells reach their normal size. Cell division may be regulated in part by dilution of Wee1 protein in cells as they grow larger. Cell cycle and growth

Cell size regulation in mammals

The protein mTOR is a serine/threonine kinase that regulates translation and cell division. Nutrient availability influences mTOR so that when cells are not able to grow to normal size they will not undergo cell division. The details of the molecular mechanisms of mammalian cell size control are currently being investigated. The size of post-mitotic neurons depends on the size of the cell body, axon and dendrites. In vertebrates, neuron size is often a reflection of the number of synaptic contacts onto the neuron or from a neuron onto other cells. For example, the size of motoneurons usually reflects the size of the motor unit that is controlled by the motoneuron. Invertebrates often have giant neurons and axons that provide special functions such as rapid action potential propagation. Mammals also use this trick for increasing the speed of signals in the nervous system, but they can also use myelin to accomplish this, so most human neurons are releatively small.

Other experimental systems for the study of cell size regulation

One common means to produce very large cells is by cell fusion to form syncytia. For example, very long (several inches) skeletal muscle cells are formed by fusion of thousands of myocytes. Genetic studies of the fruit fly Drosophila have revealed several genes that are required for the formation of multinucleated muscle cells by fusion of myocyes. Some of the key proteins are important for cell adhesion between myocytes and some are involved in adhesion-dependent cell-to-cell signaling that allows for a cascade of cell fusion events. Oocytes can be unusually large cells in species for which embryonic development takes place away from the mother's body. Their large size can be achieved either by pumping in cytosolic components from adjacent cells through cytoplasmic bridges (Drosophila) or by internalization of nutrient storage granules (yolk granules) by endocytosis (frogs). Increases in the size of plant cells is complicated by the fact that almost all plant cells are inside of a solid cell wall. Under the influence of certain plant hormones the cell wall can be remodeled, allowing for increases in cell size that are important for the growth of some plant tissues. Most unicellular organisms are microscopic in size, but there are some giant bacteria and protozoa that are visible to the naked eye. See: [http://wikibooks.org/wiki/Biology_Cell_biology_Introduction_Cell_size Table of cell sizes] - [http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10205058 Dense populations of a giant sulfur bacterium in Namibian shelf sediments] - [http://www.bms.ed.ac.uk/research/others/smaciver/chaos.htm Large protists of the genus Chaos, closely related to the genus Amoeba]

Cell reproduction

The process of cell reproduction has three major parts. The first part of cell reproduction involves the replication of the parental cell's DNA. The second major issue is the separation of the duplicated DNA into two equally sized groups of chromosomess. The third major aspect of cell reproduction is the physical division of entire cells, usually called cytokinesis. Cell reproduction is more complex in eukaryotes than in other organisms. Non-eukaryotic cells such as bacterial cells reproduce by binary fission, a process that includes DNA replication, chromosome segregation, and cytokinesis. Eukaryotic cell reproduction either involves mitosis or a more complex process called meiosis. Mitosis and meiosis are sometimes called the two "nuclear division" processes. Binary fission is similar to eukaryotic cell reproduction that involves mitosis. Both lead to the production of two daughter cells with the same number of chromosomes as the parental cell. Meiosis is used for a special cell reproduction process of diploid organisms. It produces four special daughter cells (gametes) which have half the normal cellular amount of DNA. A male and a female gamete can then combine to produce a zygote, a cell which again has the normal amount of chromosomes. For details see the individual articles on DNA replication, binary fission, mitosis, meiosis, and cytokinesis. The rest of this article is a comparison of the main features of the three types of cell reproduction that either involve binary fission, mitosis, or meiosis. The diagram below depicts the similarities and differences of these three types of cell reproduction. cytokinesis

Comparison of the three types of cell reproduction

The DNA content of a cell is duplicated at the start of the cell reproduction process. Prior to DNA replication, the DNA content of a cell can be represented as the amount Z (the cell has Z chromosomes). After the DNA replication process, the amount of DNA in the cell is 2Z (multiplication: 2 x Z = 2Z). During Binary fission and mitosis the duplicated DNA content of the reproducing parental cell is separated into two equal halves that are destined to end up in the two daughter cells. The final part of the cell reproduction process is cell division, when daughter cells physically split apart from a parental cell. During meiosis, there are two cell division steps that together produce the four daughter cells. After the completion of binary fission or cell reproduction involving mitosis, each daughter cell has the same amount of DNA (Z) as what the parental cell had before it replicated its DNA. These two types of cell reproduction produced two daughter cells that have the same number of chromosomes as the parental cell. After meiotic cell reproduction the four daughter cells have half the number of chromosomes that the parental cell originally had. This is the haploid amount of DNA, often symbolized as N. Meiosis is used by diploid organisms to produce haploid gametes. In a diploid organism such as the human organism, most cells of the body have the haploid amount of DNA, 2N. Using this notation for counting chromosomes we say that human somatic cells have 46 chromosomes (2N = 46) while human sperm and eggs have 23 chromosomes (N = 23). Humans have 23 distinct types of chromosomes, the 22 autosomes and the special category of sex chromosomes. There are two distinct sex chromosomes, the X chromosome and the Y chromosome. A diploid human cell has 23 chromosomes from that person's father and 23 from the mother. That is, your body has two copies of human chromosome number 2, one from each of your parents.

Chromosomes

Immediately after DNA replication a human cell will have 46 "double chromosomes". In each double chromosome there are two copies of that chromosome's DNA molecule. During mitosis the double chromosomes are split to produce 92 "single chromosomes", half of which go into each daughter cell. During meiosis, there are two chromosome separation steps which assure that each of the four daughter cells gets one copy of each of the 23 types of chromosome (see meiosis for details).

Why we have sex

Main article: Evolution of sex If the type of cell reproduction that uses mitosis can reproduce our cells, why do we bother with the more complicated process of meiosis? You may think you know why you have sex, but you probably do not know the real reason; the reason why meiosis confers a selective advantage. Notice that when meiosis starts, the two copies of chromosome number 2 are adjacent to each other. During this time, there can be genetic recombination events. Parts of the chromosome 2 DNA that you got from your mother (red) will swap over to the chromosome 2 DNA molecule that you got from your father (green). Notice that in mitosis the two copies of chromosome number 2 do not interact. It is these new combinations of parts of chromosomes that provide the major advantage for sexually reproducing organisms by allowing for new combinations of genes and more efficient evolution. However, in organisms with more than one set of chromosomes at the main life cycle stage, sex may also provide an advantage because, under random mating, it produces homozygotes and heterozygotes according to the Hardy-Weinberg ratio.

Morphogenesis

Morphogenesis (from the Greek morphê shape and genesis creation) is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation. Morphogenesis is concerned with the shapes of tissues, organs and entire organisms and the positions of the various specialized cell types. Cell growth and differentiation can take place in cell culture or inside of tumor cell masses without the normal morphogenesis that is seen in an intact organism. The study of morphogenesis involves an attempt to understand the processes that control the organized spatial distribution of cells that arises during the embryonic development of an organism and which give rise to the characteristic forms of tissues, organs and overall body anatomy. In the human embryo, the change from a cluster of nearly identical cells at the blastula stage to a post-gastrulation embryo with structured tissues and organs is controlled by the genetic "program" and can be modified by environmental factors. Some of the earliest ideas on how physical and mathematical processes and constraints affect biological growth were written by D'Arcy Wentworth Thompson and Alan Turing. These works postulated the presence of chemical signals and physico-chemical processes such as diffusion, activation and deactivation in cellular and organismic growth. The fuller understanding of the mechanisms involved in actual organisms required the discovery of DNA and the development of molecular biology and biochemistry. Several types of molecules are particularly important during morphogenesis. Morphogens are soluble molecules that can diffuse and carry signals that control cell differentiation decisions in a concentration-dependent fashion. Morphogens typically act through binding to specific protein receptors. An important class of molecules involved in morphogenesis are transcription factor proteins that determine the fate of cells by interacting with DNA. These can be coded for by master regulatory genes and either activate or deactivate the transcription of other genes and, in turn, these secondary gene products can regulate the expression of still other genes in a regulatory cascade. Another class of molecules involved in morphogenesis are molecules that control cell adhesion. For example, during gastrulation clumps of stem cells switch off their cell-to-cell adhesion, become migratory, and take up new positions with an embryo where they again activate specific cell adhesion proteins and form new tissues and organs. Several examples that illustrate the roles of morphogens, transcription factors and cell adhesion molecules in morphogenesis are discussed below.

Anterior-posterior axis patterning in Drosophila

Morphogenesis of the fruit fly Drosophila melanogaster starts with the construction of asymmetries within the oocyte and proceeds to pattern formation along the embryonic axes. The development of Drosophila is particularly well studied, and it is representative of one major class of insects. Other multicellular organisms sometimes use similar mechanisms for axis formation, although the relative importance of signal transfer between the earliest cells of many developing organisms is greater than in the example described here.

Maternal effect genes

oocyte A Drosophila oocyte is a polarized cell. The future anterior-posterior axis of the fly is established by mRNA molecules that are differentially localized within the oocyte. The genes that code for these differentially localized oocyte mRNAs are called maternal effect genes. They have profound effects on the development of a fertilized egg, but they are expressed by cells within the maternal ovary. Bicoid and hunchback are the maternal effect genes that are most important for patterning of anterior parts (head and thorax) of the Drosophila embryo. Nanos and Caudal are maternal effect genes that are important in the formation of more posterior abdominal segments of the Drosophila embryo. Cytoskeletal elements such as microtubules are polarized within the oocyte and can be used to allow the localization of mRNA molecules to specific parts of the cell. Maternally synthesized bicoid mRNAs attach to microtubules and are concentrated at the anterior ends of forming Drosophila eggs. Nanos mRNAs also attach to the egg cytoskeleton but they concentrate at the posterior ends of the eggs. Hunchback and caudal mRNAs lack special location control systems and are fairly evenly spread throughout the interior of egg cells. microtubule When the mRNAs from the maternal effect genes are translated into proteins a Bicoid protein gradient forms at the anterior end of the egg. Nanos protein forms a gradient at the posterior end. The Bicoid protein blocks translation of caudal mRNA so Caudal protein is made only in the posterior part the cell. Nanos protein binds to the hunchback mRNA and blocks its translation in the posterior end of Drosophila embryos. The Bicoid, Hunchback, and Caudal proteins are transcription factors. Bicoid has a DNA-binding homeodomain that binds both DNA and the nanos mRNA. Bicoid binds a specific RNA sequence in the 3' untranslated region of caudal mRNA and blocks translation. Hunchback protein levels in the early embryo are significantly augmented by new hunchback gene transcription and translation of the resulting zygotically produced mRNA. During early Drosophila embryogenesis there are nuclear divisions without cell division. The many nuclei that are produced distribute themselves around the periphery of the cell cytoplasm. Gene expression in these nuclei is regulated by the Bicoid, Hunchback, and Caudal proteins. For example, Bicoid acts as a transcriptional activator of hunchback gene transcription. zygotically zygotically

Gap genes

The other important function of the gradients of Bicoid, Hunchback, and Caudal proteins is in the transcriptional regulation of other zygotically expressed proteins. Many of these are the protein products derived from members of the "gap" family of developmental control genes. Hunchback, krüppel, giant, tailless and knirps are all gap genes. Their expression patterns in the early embryo are determined by the maternal effect gene products and shown in the diagrams on the left side of this page. The gap genes are part of a larger family called the segmentation genes. These genes establish the segmented body plan of the embryo along the anterior-posterior axis. The segmentation genes specify 14 "parasegments" that are closely related to the final anatomical segments. The gap genes are the first layer of a hierarchical cascade of the segmentation control genes. Proteins such as Bicoid can be described as morphogens that act within the syncytial blastoderm of the early Drosophila embryo. These intracellular morphogens enter the nuclei and act as transcription factors to control expression of the gap genes. In the blastoderm stage of Drosophila morphogenesis four types of nuclear specification can be distinguished:
- Anterior (head and thorax)
- Posterior (abdomen)
- Dorso-ventral
- Terminal (special structures at the unsegmented ends of the embryo)

Additional segmentation genes

ventral Two additional classes of segmentation genes are expressed after the gap gene products. The pair-rule genes are expressed in striped patterns of seven bands perpendicular to the anterior-posterior axis (see the example, even-skipped). These patterns of expression are established within the syncytial blastoderm. After these initial patterning events, cell membranes form around the nuclei of the syncytial blastoderm converting it to a cellular blastoderm. ventral The expression patterns of the final class of segmentation genes, the segment polarity genes, are then fine-tuned by interactions between the cells of adjacent parasegments (see the example, engrailed, to the right). The Engrailed protein is a transcription factor (yellow in figure to left) that is expressed in one row of cells at the edge of each parasegment. This expression pattern is initiated by the pair-rule genes (like even-skipped) that code for transcription factors that regulate the engrailed gene's transcription in the syncytial blastoderm. Cells that make Engrailed can make the cell-to-cell signaling protein Hedgehog (green in the figure to the left). Hedgehog is not free to move very far and activates a thin stripe of cells adjacent to the Engrailed-expressing cells. Only cells to one side of the Engrailed-expressing cells are competent to respond to Hedgehog because they express the receptor protein Patched (blue in figure to left). Cells with activated Patch receptor make the Wingless protein (red in the figure). Wingless protein acts as an extracelluar morphogen and patterns the adjacent rows of cells by activated its cell surface receptor, Frizzled in a concentration-dependent fashion. Wingless also acts on Engrailed-expressing cells to stabilize Engrailed expression after the cellular blastoderm forms. The reciprocal signaling by Hedgehog and Wingless stabilizes the boundary between each segment. The Wingless protein is called "wingless" because of the phenotype of some wingless mutants. Wingless also functioned during metamorphosis to coordinate wing formation. The transcription factors that are coded for by segmentation genes regulate yet another family of developmental control genes, the homeotic selector genes. These genes exist in two ordered groups on Drosophila chromosome 3. The order of the genes on the chromosome reflects the order that they are expressed along the anterior-posterior axis of the developing embryo. The Antennapedia group of homeotic selector genes includes labial, antennapedia, sex combs reduced, deformed, and proboscipedia. Labial and Deformed proteins are expressed in head segments where they activate the genes that define head features. Sex-combs-reduced and Antennapedia specify the properties of thoracic segments. The bithorax group of homeotic selector genes control the specializations of the third thoracic segment and the abdominal segments. In 1995, the Nobel Prize for Physiology or Medicine was awarded for studies concerning the genetic control of early embryonic development to Christiane Nüsslein-Volhard, Edward B. Lewis and Eric Wieschaus. Their researches on genetic screening for embryo patterning mutants revealed the role played in early embryologic development by Hox genes like bicoid. An example of a homeotic mutation is the so-called antennapedia mutation. In Drosophila, antennae and legs are created by the same basic "program", they only differ in a single transcription factor. If this transcription factor is damaged, the fly grows legs on its head instead of antennae. See images of this "antennapedia" mutant and others, at [http://flybase.bio.indiana.edu FlyBase]. The term morphogenesis can also be used to describe the development of unicellular life forms that do not have an embryonic stage in their life cycle, or to refer to the evolution of a body structure within a taxonomic group. Morphogenetic responses may be induced in organisms by hormones, or by environmental chemicals ranging from substances produced by other organisms to toxic chemicals or radionuclides released as pollutants.

Biological tissue

Biological tissue is a substance made up of cells that perform a similar function. The study of tissues is known as histology, or, in connection with disease, histopathology. The classical tools for studying the tissues are the wax block, the tissue stain, and the optical microscope, though developments in electron microscopy, immunofluorescence, and frozen sections have all added to the sum of knowledge in the last couple of decades. With these tools, the classical appearances of the tissues can be examined in health and disease, enabling considerable refinement of clinical diagnosis and prognosis.

Animal Tissues

There are four basic types of tissue in the body of all animals, including the human body and lowar multicellular organisms such as insects. These compose all the organs, structures and other contents.
- Epithelium - Tissues composed of layers of cells that cover organ surfaces such as surface of the skin and inner lining of digestive tract. The tissues serve for protection, secretion, and absorption.
- Connective tissue - As the name suggests, connective tissue holds everything together. Blood is considered a connective tissue.
- Muscle tissue - Muscle cells contain contractile filaments that move past each other and change the size of the cell.
- Nervous tissue - Cells forming the brain, spinal cord and peripheral nervous system.

Plant Tissues

Examples of tissue in other multicellular organisms are vascular tissue in plants, such as xylem and phloem. Plant tissues are categorized broadly into three tissue systems: the epidermis, the ground tissue, and the vascular tissue.
- Epidermis - Cells forming the outer surface of the leaves and of the young plant body.
- Vascular tissue - The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally.
- Ground tissue - Ground tissue is less differentiated than other tissues. Ground tissue manufactures nutrients by photosynthesis and stores reserve nutrients.

References

- Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (1986). Biology of Plants (4th ed.). New York: Worth Publishers. ISBN 0-87901-315-X. Category:Anatomy Category:Tissues ms:Tisu biologi ja:組織 (生物学) simple:Tissue (biological)

Anatomy

Anatomy (from the Greek anatomia, from anatemnein, to cut up, cut open), is the branch of biology that deals with the structure and organization of living things. It can be divided into animal anatomy (zootomy) and plant anatomy (phytonomy). Major branches of anatomy include comparative anatomy, histology, and human anatomy. Animal anatomy may include the study of the structure of different animals, when it is called comparative anatomy or animal morphology, or it may be limited to one animal only, in which case it is spoken of as special anatomy. From a utilitarian point of view the study of humans is the most important division of special anatomy, and this human anatomy may be approached from different points of view. From that of Medicine it consists of a knowledge of the exact form, position, size and relationship of the various structures of the healthy human body, and to this study the term descriptive or topographical human anatomy is given, though it is often, less happily, spoken of as anthropotomy. So intricate is the human body that only a small number of professional human anatomists, after years of patient observation, are complete masters of all its details; most of them specialize on certain parts, such as the brain or viscera, contenting themselves with a good working knowledge of the rest. Topographical anatomy must be learned by repeated dissection and inspection of dead human bodies. It is no more a science than a pilot's knowledge is, and, like that knowledge, must be exact and available in moments of emergency. From the morphological point of view, however, human anatomy is a scientific and fascinating study, having for its object the discovery of the causes which have brought about the existing structure of humans, and needing a knowledge of the allied sciences of embryology or developmental biology, phylogeny, and histology. Pathological anatomy (or morbid anatomy) is the study of diseased organs, while sections of normal anatomy, applied to various purposes, receive special names such as medical, surgical, gynaecological, artistic and superficial anatomy. The comparison of the anatomy of different races of humans is part of the science of physical anthropology or anthropological anatomy. In the present edition of this work the subject of anatomy is treated systematically rather than topographically. Each anatomical article contains first a description of the structures of an organ or system (such as nerves, arteries, heart, and so forth), as it is found in humans; this is followed by an account of the development (embryology) and comparative anatomy (morphology), as far as vertebrate animals are concerned; but only those parts of the lower animals which are of interest in explaining human body structure are here dealt with. The articles have a twofold purpose; first, to give enough details of structure to make the articles on physiology, surgery, medicine and pathology intelligible; and, secondly, to give the non-expert inquirer, or the worker in some other branch of science, the chief theories on which the modern scientific groundwork of anatomy is built.
- Major body systems:
- Integumentary system
- Muscular system
- Nervous system
- Reproductive system
- Respiratory system
- Excretory system
- Circulatory system
- Lymphatic system
- Skeletal system (Human skeleton)
- Endocrine system
- Digestive system
- Immune system
- Organs:
- Anus
- Appendix
- Brain
- Breast
- Colon or large intestine
- Diaphragm
- Ear
- Eye
- Heart
- Kidney
- Labia
- Larynx
- Liver
- Lung
- Nose
- Ovary
- Pharynx
- Pancreas
- Penis
- Placenta
- Rectum
- Skin
- Small intestine
- Spleen
- Stomach
- Tongue
- Uterus
- Bones in the human skeleton:
- Collar bone (clavicle)
- Thigh bone (femur)
- Humerus
- Mandible
- Patella
- Radius
- Skull
- Tibia
- Ulna
- Rib
- Vertebrae
- Pelvis
- Sternum
- Glands:
- Ductless gland
- Mammary gland
- Salivary gland
- Thyroid gland
- Parathyroid gland
- Adrenal gland
- Pituitary gland
- Pineal gland
- Tissues:
- Connective tissue
- Endothelial tissue
- Epithelial tissue
- Glandular tissue
- Lymphoid tissue
- Externally visible parts of the human body:
- Abdomen
- Arm
- Back
- Buttock
- Chest
- Ear
- Eye
- Face
- Genitals
- Head
- Joint
- Leg
- Mouth
- Neck
- Scalp
- Skin
- Teeth
- Tongue
- Other anatomic terms (not classified):
- Artery
- Coelom
- Diaphragm
- Gastrointestinal tract
- Hair
- Exoskeleton
- Lip
- Nerve
- Peritoneum
- Serous membrane
- Skeleton
- Skull
- Spinal cord
- Vein

External links

- [http://brainmaps.org High-Resolution Cytoarchitectural Primate Brain Atlases]
- [http://www.innerbody.com/htm/body.html Free online anatomy atlas]
- [http://www.npac.syr.edu/projects/vishuman/VisibleHuman.html The NPAC Visible Human Viewer]
- [http://cancerweb.ncl.ac.uk/omd/index.html On-Line Medical Dictionary]
- [http://www.bartleby.com/107/ Anatomy of the Human Body by Henry Gray]
- [http://www.rtstudents.com/ Online Radiology Anatomy Resources]
- [http://www.wikimd.org/index.php?title=Gray%27s_Anatomy Gray's Anatomy wiki]
- http://immunity-info.net Category:Anatomy ko:해부학 ja:解剖学 simple:Anatomy th:กายวิภาคศาสตร์

1990s

The 1990s refers to the years 1990 to 1999; the last decade of the 20th Century. The 90s were marked with rapid progression of globalization and global capitalism following the collapse of the Soviet Union and the end of the Cold War. Key forces shaping the decade were the Gulf War; popularization of Personal Computer and Internet leading to the dot.com boom.

Events and trends

While optimism and hopes were high following the collapse of Communism, the backlash of the Cold War's effect was only beginning, precipitating the continuation of terrorism in Third World regions that were once the frontlines for American and Soviet foreign politics, particularly in Asia. However, during the 1990s many First World economies such as the United States, Canada, Ireland, Australia, and South Korea experienced steady economic growth for nearly the entire decade. The United Kingdom, after the recession of 1991-92 and Black Wednesday, experienced a run of 51 consecutive quarters of economic growth that stretched into the new millenium. Even less affluent nations such as Malaysia saw tremendous improvements in economic prosperity and quality of life during the 1990s. Many countries, institutions, companies, and organizations also viewed the 90s decade as "a prosperous time", meaning that almost all of them rebounded after many years of failure. Some examples include Apple Computer's revival of power after being at the edge of bankruptcy, breakthroughs in many fields of technology that includes the Internet, virtual reality. Oil and Gas was discovered in many countries and Pope John Paul II's papacy reached its peak. Nevertheless, the 1990s brought tragic conflicts as well, like the Balkan Wars, the Rwandan genocide, the Battle of Mogadishu in Somalia and the first Gulf War.

Criticism/Backlash of the Decade

Despite denials from various sociologists and media pundits, some feel that the 90s were an era of increasing materialism and growing hypocrisy continued from the 1980s. In general it could still be said that the mindset of the 1980s and 1990s were more or less the same. The 1990s are also widely critized for their controversial pop culture obsessed with gore, sex, violence, and language, along with the 2000s to a somewhat lesser extent. The 1990s nonetheless have a very positive receiving into the 2000s and are still considered quite "modern" even as of 2006, with many genres of media from the decade still being quite cool among youth during the 2000s as no great revolutions in pop culture have occurred for some time and only moderate backlash of the decade itself has yet occurred. Also, while not a criticism of the decade per se, some people see the 1990s as the beginning of the 21st Century rather than the end of the 20th Century in an abstract sense based on the fact that the Cold War, a definitive phoenomenon of the 20th Century, was over by about 1991 and the tech boom began to take off a couple years after, and very 21st Century events such as the rise of the Internet and other information technologies and the expansion of Islamic terrorism began to become prominent in the 1990s.

Technology

Internet]
- The Pentium processor is developed by Intel.
- Microsoft introduces Windows 95 to the market, which gained immediate popularity.
- Explosive growth of the Internet, decrease in the cost of computers and other technology.
- Advancements with computer modems, ISDN, cable modems and DSL lead to faster connection to the Internet.
- The development of web browsers such as Netscape and Internet Explorer makes surfing the World Wide Web easier and more user friendly.
- The Java programming language is developed by Sun Microsystems.
- Businesses begin E-commerce websites; companies such as Amazon.com, eBay, AOL, and Yahoo! grew rapidly on the Internet.
- Cell phones burst in popularity and decrease in size, becoming a necessity for modern life.
- Pagers and PDAs become popular communication tools.
- E-mail becomes popular; as a result Microsoft acquires the popular Hotmail.com.
- Year 2000 problem (commonly known as Y2K).
- Microsoft Windows operating system becomes virtually ubiquitous on IBM PCs.
- Development of free operating system Linux is started.
- Breakthrough of compact disc technology, introduced in the 1980s, later branching into DVD.

Science

DVD]
- Detection of extrasolar planets orbiting stars other than the sun.
- The cloning of Dolly the sheep is achieved.
- Human Genome Project begun.
- DNA identification of individuals finds wide application in criminal law.
- Hubble Space Telescope launched in 1990; revolutionizes astronomy.
- Protease inhibitors introduced allowing HAART therapy against HIV; drastically reduces AIDS mortality.
- NASA's spacecraft Pathfinder lands on Mars and deploys a small roving vehicle, Sojourner, that analyzes the planet's geology and atmosphere.
- The Hale-Bopp comet swings past the sun for the first time in 4,200 years.
- Development of biodegradable products, replacing products made from styrofoam; advanced methods for recycling of waste products (such as paper, glass, aluminum) are developed.
- Genetically engineered crops are developed for commercial use.
- Discovery of dark matter, dark energy, and brown dwarves, and first confirmation of black holes.
- The Galileo probe orbits Jupiter, studying the planet and its moons extensively.

War, peace, and politics

Jupiter] Jupiter]
- Reunification of Germany on October 3 1990.
- End of apartheid in South Africa (1990) and election of ANC government of Nelson Mandela.
- Gulf War (resulting from Iraq's invasion of Kuwait) and United Nations embargo on Iraq in 1991.
- North Yemen and South Yemen merge to form Yemen (1991).
- Break up of the Soviet Union in 1991 - the end of the Cold War, United States as sole world superpower.
- The bombing of the World Trade Center in 1993 by an explosive-filled van leads to awareness of international terrorism as a rising threat.
- Eritrea gains independence from Ethiopia (1993).
- European Union is declared in 1992.
- Military actions in Somalia in 1993 lead to questions of the United States' role as a policing officer of the world. (see also, Black Hawk Down).
- Rwandan genocide kills one million people, in 1994.
- The birth of the "Second Republic" in Italy, with the Mani Pulite investigations of 1994.
- Peace process begins in Northern Ireland in 1995
- Balkan war in former Yugoslavia in 1995.
- A decade of women presidents in the Republic of Ireland.
- The United Kingdom hands sovereignty of Hong Kong to the People's Republic of China on July 1, 1997.
- U.S. Congressman Newt Gingrich crafts his manifesto "Contract with America", leading his Republican Party to become the controlling majority in the U.S. House of Representatives.
- U.S. president Bill Clinton's sex scandal with Monica Lewinsky and his impeachment trial in 1998, which lasts the entire year.
- Anti-globalization protests.
- The Second Congo War start in 1998 in central Africa and includes 5 different cultures and 7 different nations. It goes on until 2002.
- In May 1999, Pakistan sends troops covertly to occupy strategic peaks in Kashmir. A month later the Kargil War with India results in a political fiasco for Nawaz Sharif, followed by a military withdrawal to the Line of Control. The incident leads to a military coup in October in which the Prime Minister Nawaz Sharif is ousted by Army Chief Pervez Musharraf.
- Portugal hands sovereignty of Macau to the People's Republic of China on December 20, 1999.

Economics

- Development of GATT, the World Trade Organization and other global economic institutions.
- The North American Free Trade Agreement (NAFTA), which phases out trade barriers between the United States, Mexico and Canada is signed into law by U.S. President Bill Clinton.
- After 1992 the booming of the US stock market, in reference to which Alan Greenspan coined the memorable phrase "irrational exuberance", which eventually stretched into the dot-com boom / dot-com bubble.
- Financial crisis hits East and Southeast Asia in 1997 and 1998 after a long period of phenomenal economic development. See East Asian Tigers.

Culture

Trends/Various

- The Gay 1990s The 1990s saw an increase in gay visibility. Tv shows like thirtysomething,My So called Life and Ellen featured gay characters, Movies like The Birdcage,In and Out and Kiss Me Guido saw mainstream sucess, and celebrities like K.D Lang and George Michael coming out of the closet. Even President Bill Clinton generally held a pro gay rights viewpoint.
- Douglas Coupland publishes the novel Generation X: Tales for an Accelerated Culture, popularizing the term Generation X as the name of the generation born in the late 1960s and early 1970s (then college-age).
- Reality television explodes on MTV with the popularity of The Real World (1992-); along with Road Rules (1995-), Real World/Road Rules Challenge (1998), and Real World reunions, these shows remained popular throughout the 1990s.
- Video games become more advanced, but still a far cry from the systems of the 2000s. The more influential game systems of the Nineties include the Super Nintendo Entertainment System, the Sony Playstation, and the Sega Dreamcast.
- Extreme sports reached a new height in popularity, and by 1995, were given their own annual tournament on US cable network ESPN, the X-Games.
- Black becomes a dominant color in fashion, among several dark colors (see Goth, The Matrix, and Regis Philbin).
- Dogma 95 becomes the leading European artistic film movement by the end of the decade.
- Professional wrestling became extremely popular. After scandals and near bankruptcy due to competition from World Championship Wrestling (WCW), the World Wrestling Federation was repackaged more edgier and realistic. Superstars such as Stone Cold Steve Austin, The Rock, Mick Foley, Steve Borden (Sting), Bill Goldberg, Raven, Sabu and others became household names. At the same time, Extreme Championship Wrestling (ECW) led wrestling's entry into edgier angles.
- Recreational sports such as rock climbing, mountain biking, sky diving, snowboarding, mountain climbing, bungee jumping, in-line skating, kayaking and rowing become hugely popular.
- Extended alcohol sales are implemented to reduce alcohol abuse.
- The 1990s remains a somewhat "cool" decade into the 2000s as many aspects of the 90s continue to be important into the next decade, see New Nineties.

Music

- Grunge music, popularized by Nirvana, big from the fall of 1991 through 1994 but influential to rock up to 2005 (see Post-Grunge), Grunge movement followed by the Britpop movement of about 1995 to 1997 which was in turn followed by numetal.
- Teen pop held over from the late 1980s popular into 1990, returns with Backstreet Boys and Spice Girls in latter third of the decade
- Radiohead comes to be one of the most critically and commercially loved bands since The Beatles. Two of their albums, The Bends and Ok Computer top lists at the end of the decade.
- Rap music gains widespread mainstream acceptance throughout the decade, starting with the success of MC Hammer, Public Enemy and Vanilla Ice around 1989-91 and ending with hip-hop inspired by Puff Daddy, Dr. Dre and Eminem c. 1997-99. By 1999 hip hop had definitely passed rock and roll in popularity.
- Music festivals such as Lollapalooza became popular; a fusing of genres from alternative rock, rap, punk rock and garage bands.
- Rock music begins to be referred to as "alternative" as it is originated in 1980s underground rock and 1970s punk and begins to lose popularity to hip hop.
- Trance, techno and electronica music becomes widely popular at rave parties in Europe/USA and in pop culture, particularly later in the decade. The drug Ecstasy, (aka MDMA or 'X') is popularized by rave culture.
- 1980s backlash, beginning in about 1991 and lasting into the 2000s. During most of the 1990s anything "Eighties" was considered to be ultimately uncool.
- Music becomes more profane, by end of decade a Parental Advisory sticker becomes acceptable rather than controversial.
- In America, country music becomes more mainstream with popular chart topping artist such as Garth Brooks, Shania Twain, LeAnn Rimes, Faith Hill, and Tim McGraw. The trend decreases somewhat in the 2000s.

Television

- Japanimation becomes popular in the United States in the late 1990s with shows Pokemon, Dragonball Z, and Cowboy Bebop.
- Mighty Morphin' Power Rangers gains popularity with kids in the mid 90s; leading to entire Power Rangers series. Barney and Teenage Mutant Ninja Turtles also popular
- MTV moves away from music videos and into original television shows such as The Real World, which is cited as the inspiration for the Reality TV boom of the 2000s.
- Cartoons aimed at an adult audience become popular. Among the most successful are The Simpsons (1989-), Ren & Stimpy (1991-1995), Beavis and Butt-head (1993-1997), South Park (1997-), King of the Hill (1997-), and Family Guy (1999-2002, 2005-).
- Television networks increase programs aimed at twenty- and thirty-somethings. Some of the popular are Beverly Hills 90210 (1990-2000), Melrose Place (1992-1999), Party of Five (1994-2000), Ally McBeal (1997-2002), Friends (1994-2004), and Seinfeld (1989-1998).
- Notable television sitcoms aimed at the teen/preteen market include Boy Meets World (1993-2000), Full House (1987-1995), Family Matters (1989-1998), and Third Rock From The Sun (1996-2001), among many others.
- Major 1990s slang words/phrases, mostly related to hip hop include "homie", "phat", "da bomb", "Audi 5000", "tight", "word to your mother", "Talk to the hand", "You go girl!", and "Wasssuppp!"

Other significant events

Talk to the hand]
- The massive global human impact on the environment, which first garnered attention in the 60s, was widely acknowledged.
- Divorce and scandal rocked the British Royal House of Windsor.
- The assassination of Selena Quintanilla.
- Sex and violence in the media increase, especially in the late part of the decade. Profanity in music reaches peak in the late 90s.
- O.J. Simpson's trial, described in the media as the "trial of the century".
- You go, girl! becomes a popular phrase in the media as feminism is more widely accepted and publicised in the media with The Spice Girls, the WNBA, women's boxing, Sex and the City and others showcasing modern femininity.
- The Vieques controversy.
- The Oklahoma City Bombing, the bombing of a federal building in Oklahoma City, Oklahoma, killing 168.
- The Waco massacre prompts a nationwide debate in the U.S. about the freedom of association right of the Michigan Militia, Montana Militia and other radical groups.
- Crime levels in the U.S. peak in 1991, begin to fall afterwards to the lowest levels since the late 1960s at end of decade.
- Drug use in the U.S. reaches an all-time low in 1992 before increasing, reaching its peak in 1997 before declining again.
- Princess Diana dies in a car accident in 1997. Debates of accident vs assassination rage.
- Mother Teresa, the Roman Catholic nun who won the Nobel Peace Prize, dies at age 87.
- 21-year-old Golfer Tiger Woods wins the Masters Tournament by a record 12 strokes; becoming the youngest and first African-American to win the Masters.
- The Omagh bombing in Omagh, County Tyrone, Ireland which kills 29 civilians (including a woman pregnant with twins) and injures hundreds more.
- John F. Kennedy, Jr., his wife Carolyn Bessette and sister-in-law Lauren Bessette are killed when Kennedy's private plane crashes off the coast of Martha's Vineyard.
- American cyclist Lance Armstrong wins his first Tour de France in 1999, less than two years after battling testicular cancer.
- Beer keg registration becomes popular public policy in U.S.

People

World leaders

- Prime Minister Bob Hawke (Australia)
- Prime Minister Paul Keating (Australia)
- Prime Minister John Howard (Australia)
- President Fernando Affonso Collor de Mello (Brazil)
- President Itamar Franco (Brazil)
- President Fernando Henrique Cardoso (Brazil)
- Prime Minister Brian Mulroney (Canada)
- Prime Minister Kim Campbell (Canada)
- Prime Minister Jean Chrétien (Canada)
- "Paramount Leader" Deng Xiaoping (People's Republic of China)
- President Jiang Zemin (People's Republic of China)
- President Lee Teng-hui (Republic of China on Taiwan)
- President Franjo Tuđman (Croatia)
- Prime Minister Poul Nyrup Rasmussen (Denmark)
- President Hosni Mubarak (Egypt)
- President François Mitterrand (France)
- President Jacques Chirac (France)
- Chancellor Helmut Kohl (Germany)
- Chancellor Gerhard Schröder (Germany)
- Governor David Clive Wilson (Hong Kong (under British rule))
- Governor Christopher Francis Patten (Hong Kong (under British rule))
- Chief Executive Tung Chee Hwa (Hong Kong, People's Republic of China)
- Prime Minister Atal Bihari Vajpayee (India)
- President Mohammad Khatami (Iran)
- President Saddam Hussein (Iraq)
- Prime Minister Yitzhak Rabin (Israel)
- Prime Minister Benjamin Netanyahu (Israel)
- Emperor Akihito (Japan)
- Governor Vasco Joaquim Rocha Vieira (Macau (under Portuguese rule))
- Chief Executive Edmund Ho (Macau, People's Republic of China)
- President Yasser Arafat (Palestinian Authority)
- Pope Pope John Paul II
- President Corazon Aquino (Philippines)
- President Fidel Ramos (Philippines)
- President Joseph Estrada (Philippines)
- Prime Minister Mike Moore (New Zealand)
- Prime Minister Jim Bolger (New Zealand)
- Prime Minister Jenny Shipley (New Zealand)
- Prime Minister Helen Clark (New Zealand)
- President Ion Iliescu (Romania)
- President Emil Constantinescu (Romania)
- President Boris Yeltsin (Russia)
- Taoiseach Charles Haughey (Republic of Ireland)
- Taoiseach Albert Reynolds (Republic of Ireland)
- Taoiseach John Bruton (Republic of Ireland)
- Taoiseach Bertie Ahern (Republic of Ireland)
- President Boris Yeltsin (Russia)
- President Wee Kim Wee (Singapore)
- President Ong Teng Cheong (Singapore)
- President Sellapan Ramanathan (Singapore)
- President Frederik Willem de Klerk (South Africa)
- President Nelson Mandela (South Africa)
- President Kim Dae-jung (South Korea)
- President Mikhail Gorbachev (Soviet Union)
- King Juan Carlos I (Spain)
- President Felipe González (Spain)
- President José María Aznar (Spain)
- Queen Elizabeth II (United Kingdom et al.)
- Prime Minister John Major (United Kingdom)
- Prime Minister Tony Blair (United Kingdom)
- President George H.W. Bush (United States)
- President Bill Clinton (United States)
- President Slobodan Milošević (Federal Republic of Yugoslavia)

Entertainers

Federal Republic of Yugoslavia] Federal Republic of Yugoslavia]] Federal Republic of Yugoslavia
- 2pac
- Ace of Base
- Adam Sandler
- Aaliyah
- Alice in Chains
- Alanis Morrissette (Jagged Little Pill)
- Annie Lennox
- Anthony Hopkins (The Silence of the Lambs, Titus)
- Ashley Judd
- Beavis and Butt-Head
- Ben Affleck (Good Will Hunting)
- Bill Hicks
- Billy Bob Thornton
- Boyz II Men
- Bret Hart
- Britney Spears
- Bruce Willis (the Die Hard series, Pulp Fiction)
- Mariah Carey
- Dana Carvey (Wayne's World)
- Dean Cain
- Carmen Electra
- Christina Aguilera
- Cuba Gooding Jr (Boyz N the Hood, Jerry Maguire)
- Amy Grant
- Dave Matthews Band
- Demi Moore (Ghost, Striptease, A Few Good Men)
- Denzel Washington ( Malcolm X, Mo' Better Blues, Philadelphia)
- Destiny's Child (Destiny's Child, The Writing's On The Wall)
- Ellen DeGeneres (Ellen)
- Elizabeth Berkley (Saved by the Bell, Showgirls)
- Eurythmics
- Friends
- Courtney Cox
- Jennifer Aniston
- Lisa Kudrow
- Matt LeBlanc
- Matthew Perry
- David Schwimmer
- The Fugees
- Green Day (Dookie, Nimrod)
- Gwyneth Paltrow (Shakespeare in Love, The Talented Mr. Ripley, Se7en)
- Liam Gallagher of Oasis
- Noel Gallagher of Oasis
- Teri Hatcher
- Whitney Houston (The Bodyguard, Waiting to Exhale)
- Halle Berry (Introducing Dorothy Dandridge,Bullworth)
- Hanson
- Harrison Ford
- Helen Hunt (Mad About You, Twister, As Good as It Gets)
- Hootie & The Blowfish
- Jack Nicholson
- Jerry Seinfeld (Seinfeld)
- Jerry Springer
- Jim Carrey (Ace Ventura: Pet Detective, The Mask)
- Julia Roberts (Pretty Woman, Notting Hill)
- Kate Winslet (Titanic)
- Keanu Reeves (The Matrix)
- Kurt Cobain
- Leonardo DiCaprio (Titanic)
- Liam Neeson
- Macaulay Culkin (Home Alone)
- The Undertaker
- Martin Lawrence (House Party, Martin, Bad Boys)
- Mary J Blige (What's the 411?)
- Matt Damon (Good Will Hunting)
- Meg Ryan
- Mel Gibson (Braveheart)
- Michael Jackson
- Michael Keaton
- Michelle Pfeiffer (The Age of Innocence, Batman Returns)
- Mike Myers (Wayne's World, Saturday Night Live, Austin Powers)
- Mira Sorvino
- Nicole Kidman (My Life, Eyes Wide Shut)
- Notorious B.I.G.
- Nirvana
- Oasis
- Phil Collins
- Pamela Anderson (Baywatch)
- Pearl Jam
- "Image:Princesymbol.png" The artist formerly known as Prince
- Queen Latifah (Living Single, Set It Off)
- Quentin Tarantino (Pulp Fiction)
- Ralph Fiennes (Schindler's List, The English Patient)
- Jeri Ryan (Star Trek: Voyager)
- Samuel L. Jackson (Goodfellas, Pulp Fiction)
- Sandra Bullock (Speed, A Time to Kill)
- Shawn Michaels
- Spice Girls
- Stone Cold Steve Austin
- Tim Burton (Edward Scissorhands, Batman Returns)
- Tiffani-Amber Thiessen (Saved by the Bell, Beverly Hills 90210 )
- TLC (Lisa "Left-Eye" Lopes, T-Boz, Rozonda "Chilli" Thomas)
- Tom Hanks (Forrest Gump, Saving Private Ryan, Philadelphia, Toy Story, The Green Mile)
- Toni Braxton ( Toni Braxton (album) )
- U2 (Achtung Baby)
- Uma Thurman (Pulp Fiction)
- Whoopi Goldberg (Sister Act, Ghost, Ghosts of Mississippi, Hollywood Squares)
- Will Smith (The Fresh Prince of Bel Air, Men In Black)

Films

See also: 1990s in film

Books & Literature

Sports figures

Synthesis

:: This is an article about the philosophical concept. For information regarding the magazine, see Synthesis (Magazine) Synthesis (from the Greek words syn = plus and thesis = position) is commonly understood to be an integration of two or more pre-existing elements which results in a new creation.

Philosophical synthesis

The term is broad in meaning and can apply to physical, ideological, and/or phenomenological entities. In dialectics, synthesis is the final result of attempts to reconcile the inherent contradiction between thesis and antithesis. Along with the similar concept of integration, synthesis is generally considered to be an important element of modern philosophy, particularly in the various emerging ideas often considered to be holistic (as opposed to reductionistic).

Chemical synthesis

In chemistry, chemical synthesis is the process of forming a particular molecule from chemical precursors.

Synthesis in electronics and acoustics

In electronic musical instruments, sound synthesis is the method of sound generation a piece of hardware or software may employ, E.g. "Musically, "My lovely Access Virus B" mainly uses subtractive synthesis but it's got a bit of FM synthesis too." Modern electronic keyboard instruments are based around digital sound synthesizers that create audio waveforms that sound like they came from a violin or koto, without an actual violin or koto, because the sound is synthesized. A Video Synthesizer electronically creates TV signals without necessarily requiring the use of a TV camera. Moving abstract patterns, text subtitles, colorized or processed camera images can all be in the output of a video synthesizer. Analog video synthesizers included the Sandin Image Processor, the Rutt-Etra, Steve Beck's "Beck Direct" Synthesizer, Bill Hearn's colorizer, and the seminal work of Nam Jun Paik. Early digital synthesizers included Stephen Beck's Video Weavings, the 2901 bit slice processor from Steina and Woody Vasulka with Schier and Dosch, Sandin's Digital Image Colorizer, Etra's "Kangaroo Giant Box" , and the Fluidigeo Synthesizer. Documentation on the history of video synthesizers can also be found at http://www.experimentaltvcenter.org/history/index.html. In the world of electronic design automation, synthesis is the process of converting a digital design written in a hardware description language (HDL) into a low-level implementation consisting of primitive logic gates. Most large integrated circuits designed today are written in an HDL and "compiled" using a synthesis product. The first (and still most popular) synthesis tool was written by Synopsys.

External links

- [http://www.swemorph.com/pdf/anaeng-r.pdf Analysis and Synthesis: On Scientific Method based on a study by Bernhard Riemann] From the Swedish Morphological Society.

Category:Biology

Biology is the science of life. It is concerned with the characteristics and behaviors of organisms; how individuals come into existence, and how species evolve; and the interactions they have with each other and with their environment. Biology encompasses a broad spectrum of academic fields that are often considered independent disciplines many of which are listed below as subcategories. Category:Life Category:Science Category:Environmental science Category:Academic disciplines ko:분류:생물학 ms:Category:Biologi ja:Category:生物学 simple:Category:Biology

Adam Poniński

Znanych jest kilka osób o nazwisku Adam Poniński:
- Adam Poniński (zm. 1798)
- Adam Poniński (zm. 1816)

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