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Cell (biology)

Cell (biology)
The cell (from Latin cella, meaning "small room"[1]) is the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology. The cell was discovered by Robert Hooke in 1665. Anatomy There are two types of cells, eukaryotes, which contain a nucleus, and prokaryotes, which do not. Prokaryotic cells A prokaryotic cell has three architectural regions: On the outside, flagella and pili project from the cell's surface. Eukaryotic cells Structure of a typical animal cell Plants, animals, fungi, slime moulds, protozoa, and algae are all eukaryotic. Subcellular components Illustration depicting major structures inside a eukaryotic animal cell Membrane Cytoskeleton A fluorescent image of an endothelial cell. Genetic material Organelles There are several types of organelles in a cell. Eukaryotic Related:  Cells...

- Research Group ANPRON Enquête 2014 sur Mozilla Firefox - Vendredi, 18 Avril 2014 Question : 1 sur 4 De quel sexe êtes-vous ? Question : 2 sur 4 À partir d'où utilisez-vous Mozilla Firefox ? Question : 3 sur 4 Combien de fois utilisez-vous Mozilla Firefox ? Question : 4 sur 4 Naviguez-vous sur Mozilla Firefox sur ​​votre téléphone mobile ? Envoi de réponses ... ©2014 All Rights Reserved. Your privacy is important to us. Anatomy Anatomy is the branch of biology concerned with the study of the structure of animals and their parts; it is also referred to as zootomy to separate it from human anatomy. In some of its facets, anatomy is related to embryology and comparative anatomy, which itself is closely related to evolutionary biology and phylogeny.[1] Human anatomy is one of the basic essential sciences of medicine. Definition[edit] Human compared to elephant frame Anatomical chart by Vesalius, Epitome, 1543 The discipline of anatomy can be subdivided into a number of branches including gross or macroscopic anatomy and microscopic anatomy.[4] Gross anatomy is the study of structures large enough to be seen with the naked eye, and also includes superficial anatomy or surface anatomy, the study by sight of the external body features. The term "anatomy" is commonly taken to refer to human anatomy. Animal tissues[edit] A diagram of an animal cell Unlike plant cells, animal cells have neither a cell wall nor chloroplasts.

Cell In biology, the cell is the basic structure of organisms. All cells are made by other cells. Kinds of cells[change | edit source] There are two basic kinds of cells: prokaryotic cells and eukaryotic cells. Eukaryotes are complex cells with many organelles and other structures in the cell. Kinds of prokaryotic organisms[change | edit source] The only kinds of prokaryotic organisms alive at present are bacteria and archaea. Kinds of eukaryotic organisms[change | edit source] Unicellular[change | edit source] A paramecium Unicellular organisms are made up of one cell. Unicellular organisms live without other cells to help them. eatmoverespire (use oxygen to make sugar into energy)sense its environment All organisms must: get rid of wastereproduce (make more of itself)grow Some may: get their energy from the sun (e.g., cyanobacteria)ferment (e.g., yeasts)use anaerobic respiration (e.g. Multicellular[change | edit source] Multicellular organisms are made from many cells.

Neuroscience Neuroscience is the scientific study of the nervous system.[1] Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics, medicine and allied disciplines, philosophy, physics, and psychology. It also exerts influence on other fields, such as neuroeducation[2] and neurolaw. Because of the increasing number of scientists who study the nervous system, several prominent neuroscience organizations have been formed to provide a forum to all neuroscientists and educators. History[edit] The study of the nervous system dates back to ancient Egypt. Early views on the function of the brain regarded it to be a "cranial stuffing" of sorts. The view that the heart was the source of consciousness was not challenged until the time of the Greek physician Hippocrates. Modern neuroscience[edit] Human nervous system

Cellule (biologie) Un article de Wikipédia, l'encyclopédie libre. Pour les articles homonymes, voir cellule. Cellules épithéliales en culture. La théorie cellulaire implique l'unité de tout le vivant : tous les êtres vivants sont composés de cellules dont la structure fondamentale est commune ainsi que l'homéostasie du milieu intérieur, milieu de composition physico-chimique régulé et propice au développement des cellules de l'espèce considérée. Dessin de « cellules » observées dans des coupes d'écorce d'arbre par Robert Hooke en 1665. Le nombre de cellules propres à un organisme humain adulte est de l'ordre de 1014. La cellule est l'unité constitutive des organismes vivants. Ici on se demande avant tout quelles sont les caractéristiques communes aux cellules, malgré leur diversité. Une petite section d'une membrane cellulaire. La cellule constitue une unité spatiale, délimitée par une membrane. La membrane plasmique crée donc un espace clos en constant échange avec l'environnement proche.

Zoology Zoology (/zoʊˈɒlədʒi/, zoh AHL uh jee) or animal biology, is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct. The term is derived from Ancient Greek ζῷον, zōon, i.e. "animal" and λόγος, logos, i.e. "knowledge, study".[1] History[edit] Ancient history to Darwin[edit] The history of zoology traces the study of the animal kingdom from ancient to modern times. Over the 18th and 19th centuries, zoology became an increasingly professional scientific discipline. Post-Darwin[edit] These developments, as well as the results from embryology and paleontology, were synthesized in Charles Darwin's theory of evolution by natural selection. Research[edit] Structural[edit] Physiological[edit] Animal anatomical engraving from Handbuch der Anatomie der Tiere für Künstler. Evolutionary[edit] Systematics[edit] Many scientists now consider the five-kingdom system outdated.

Cell biology Understanding cells in terms of their molecular components. Knowing the components of cells and how cells work is fundamental to all biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology as well as to biomedical fields such as cancer research and developmental biology. These fundamental similarities and differences provide a unifying theme, sometimes allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Processes[edit] Movement of proteins[edit] Endothelial cells under the microscope. Each type of protein is usually sent to a particular part of the cell. Extracellular and cell surface proteins destined to be degraded can move back into intracellular compartments upon being incorporated into endocytosed vesicles, some of which fuse with lysosomes where the proteins are broken down to their individual amino acids. See also[edit]

Why this crab's blood could save your life Nearly 50 years ago, scientists discovered the horseshoe crab's clotting-response to bacterial toxins. Now, its blood is harvested in huge quantities, to be used in a test to ensure medical products are not contaminated. Charles River Laboratories manufactures the tests, and is working to raise awareness about the importance of this prehistoric species and the need to protect them. The company helped pass landmark legislation to protect the horseshoe crab in South Carolina, a key spawning ground where it collects crabs. Limulus amebocyte lysate (LAL), a reagent which is extracted from the horseshoe crab's blue blood, can detect just one picogram of harmful bacterial endotoxin per milliliter -- equivalent to one grain of sand in an Olympic-size pool. More than 600,000 crabs are captured each year to "donate" around 30% of their blood. Once part of their blood has been collected the crabs are returned to the sea. Life-saving crab Prehistoric species Blue blood Harvesting crabs by hand

Category:Cell biology Science/Nature | Geological time gets a new period Geologists have added a new period to their official calendar of Earth's history - the first in 120 years. The Ediacaran Period covers some 50 million years of ancient time on our planet from 600 million years ago to about 542 million years ago. It officially becomes part of the Neoproterozoic, when multi-celled life forms started to take hold on Earth. However, Russian geologists are unhappy their own title - the Vendian - which was coined in 1952, was not chosen. The decision was taken after a fifteen-year long period of consideration by expert geologists. "There's always been a recognition that the last part of the Precambrian is a special time before the first shelled animals, when there are these weird, mesh-like creatures of uncertain affinity," Professor Jim Ogg, secretary-general of the International Commission on Stratigraphy (ICS), told BBC News Online. "Now it's an official part of the timescale." 'Snowball' Earth

4. The Cell: Down to Basics [Beyond Books - Life Science: Part 1] What do a two-foot-long neuron, a two pound ostrich egg, and .2-micrometer-long bacteria all have in common? Each is a single cell. Cells are the basic unit of structure and function in living things, the smallest things that can perform all of the functions of life. Aside from the occasional ostrich egg or nerve cell, most cells are very small and can't be seen without magnification. As a result, our knowledge of cells has grown as technology has allowed us to see them. Robert Hooke, an English scientist, first described cells in 1665. In 1675, a Dutch lens maker named Antonie van Leeuenhoek described the first living cells. In 1838, Dutch botanist Matthias Schleiden concluded that all plants are composed of cells. All living things are made of cells. The cell is the smallest living thing that can perform all the functions of life. All cells must come from preexisting cells. All life on Earth can be divided into two categories: eukaryotes and prokaryotes.

Neurons in human skin perform advanced calculations - Faculty of Medicine - Umeå University, Sweden [2014-09-01] Neurons in human skin perform advanced calculations, previously believed that only the brain could perform. This is according to a study from Umeå University in Sweden published in the journal Nature Neuroscience. A fundamental characteristic of neurons that extend into the skin and record touch, so-called first-order neurons in the tactile system, is that they branch in the skin so that each neuron reports touch from many highly-sensitive zones on the skin. According to researchers at the Department of Integrative Medical Biology, IMB, Umeå University, this branching allows first-order tactile neurons not only to send signals to the brain that something has touched the skin, but also process geometric data about the object touching the skin. The study also shows that the sensitivity of individual neurons to the shape of an object depends on the layout of the neuron’s highly-sensitive zones in the skin. Read the study in Nature Neuroscience Editor: Mattias Grundström Mitz