Endochondral and intramembranous are two mechanisms of?
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bone formation\nendochondral ossification (long bones)\nmembraneous ossification (flat bones (skull))
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It would depend on several factors. Small, uncharged molecules can pass through the cell membrane through diffusion. When it is water, it is called osmosis. Diffusion can only occur into the cell when the concentration of the substance is greater outside the cell than within it, and likewise only out of the cell when the concetration is greater inside the cell than outside. This is called the concentration gradient.\n\nWhen the molecule is charged or is large (such as a chlorine ion or a lactose molecule), it requires active transport by carrier proteins. There are also carrier proteins that help to transport against the concentration gradient.\n\n[Edit] \nAfter thinking for a bit, I believe it would be pertinent to include something about the more complex methods of active transport.\n\nThere are two "directions" of the complex forms of active transport: in (endocytosis) and out (exocytosis).\n\nExocytosis is when a vesicle, after being released from the Golgi complex, fuses to the cell membrane, releasing the contents.\n\nEndocytosis is done by three main means: Phagocytosis, Pinocytosis, and Receptor-Mediated Endocytosis.\n\nPhagocytosis is the process of enveloping a large particle, such as how many unicellular organisms "eat" other organisms. The large particle comes in contact with the cell membrane, stimulating the formation of a vesicle. This vesicle then enters the cell and depending on the contents may fuse with a lysosome to help to digest it.\n\nPinocytosis also forms a vesicle, but differs from phagocytosis because it forms a much smaller vesicle.\n\nReceptor-mediated endocytosis is when particles that cannot normally enter the cell bond to receptor proteins embedded in the cell membrane. These proteins then congregate and form a vesicle. \n\nIn all forms of endocytosis and exocytosis, ATP is required for energy.
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Hi Anita. I believe the best answer is D) histology.\n\nAnatomy is a much broader area than this.\nCell biology is more concerned with the internal functions of the cell.\nChemistry is not directly involved with how cells are arranged.\nPhysiology is a much broader area of study.\n\nHope this is helpful for you.  Best wishes.
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The nuclear envelope has two membranes, each with the typical unit membrane structure. They enclose a flattened sac and are connected at the nuclear pore sites. The outermost membrane is continuous with the rough endoplasmic reticulum (ER) and has ribosomes  attached. The space between the outer and inner membranes is also continuous with rough endoplasmic reticulum space. It can fill with newly synthesized proteins just as the rough endoplasmic reticulum does. The nuclear envelope is enmeshed in a network of filaments for stability.
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Animals have a circulatory system that transports fluids, chemicals, and nutrients around within the animal body. Some plants have an analogous system: the vascular system in vascular plants; trumpet hyphae in bryophytes.\n\nRoot hairs are thin-walled extensions of the epidermal cells in roots. They provide increased surface area and thus more efficient absorption of water and minerals. Water and dissolved mineral nutrients enter the plant via two routes. \n\n\nWater and selected solutes pass through only the cell membrane of the epidermis of the root hair and then through plasmodesmata on every cell until they reach the xylem: intracellular route (apoplastic). Water and solutes enter the cell wall of the root hair and pass between the wall and plasma membrane until the encounter the endodermis, a layer of cells that they must pass through to enter the xylem: extracellular route (symplastic). \n\n\nThe endodermis has a strip of water-proof material (containing suberin) known as the Casparian strip that forces water through the endodermal cell and in such a way regulates the amount of water getting to the xylem. Only when water concentrations inside the endodermal cell fall below that of the cortex parenchyma cells does water flow into the endodermis and on into the xylem.\nXylem and Transport \nXylem is the water transporting tissue in plants that is dead when it reaches functional maturity. Tracheids are long, tapered cells of xylem that have end plates on the cells that contain a great many crossbars. Tracheid walls are festooned with pits. Vessels, an improved form of tracheid, have no (or very few) obstructions (crossbars) on the top or bottom of the cell. The functional diameter of vessels is greater than that of tracheids.\n\nWater is pulled up the xylem by the force of transpiration, water loss from leaves. Mature corn plants can each transpire four gallons of water per week. Transpiration rates in arid-region plants can be even higher. Water molecules are hydrogen bonded to each other. Water lost from the leaves causes diffusion of additional water molecules out of the leaf vein xylem, creating a tug on water molecules along the water columns within the xylem. This "tug" causes water molecules to rise up from the roots to eventually the leaves. The loss of water from the root xylem allows additional water to pass throught the endodermis into the root xylem.\n\nCohesion is the ability of molecules of the same kind to stick together. Water molecules are polar, having slight positive and negative sides, which causes their cohesion. Inside the xylem, water molecules are in a long chain extending from the roots to the leaves. \n\nAdhesion is the tendency of molecules of different kinds to stick together. Water sticks to the cellulose molecules in the walls of the xylem, counteracting the force of gravity and aiding the rise of water within the xylem. \n\nCohesion-Adhesion Theory\nTranspiration exerts a pull on the water column within the xylem. The lost water molecules are replaced by water from the xylem of the leaf veins, causing a tug on water in the xylem. Adhesion of water to the cell walls of the xylem facilitates movement of water upward within the xylem. This combination of cohesive and adhesive forces is referred to as the Cohesion-Adhesion Theory.\n\n\nGuard Cells Regulate Transpiration\nIn most environments, the water concentration outside the leaf is less than that inside the leaf, causing a loss of water through openings in the leaf known as stomata (singular = stoma). Guard cells are crescent-shaped cells of the epidermis that flank the stoma and regulate the size of the opening. Together, the guard cells and stoma comprise the stomatal apparatus. The inner wall of the guard cell is thicker than the rest of the wall. When a guard cell takes up potassium ions, water moves into the cell, causing the cell to become turgid and swell, opening the stoma. When the potassium leaves the guard cell, the water
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For one thing, mitochondria have a double membrane, so the reactions that take place within it are seperate from the cytoplasm and will not disrupt any of the cell's other activities (i.e., the mitochondria is slightly more acidic than the cytoplasm). \n\nFurthermore, the inner membrane is folded to yield a lot of surface area, thus allowing for more reactions to take place.\n\nYou could also talk about how the intermembrane space (the space between the inner and outermembranes) allows for an electrochemical gradient to be built up during the process of electron transport.
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The proton pump represents the flow of protons from the mitochondrial matrix into the intermembrane space.  This flow of protons (driven by the electron transport chain) creates an electrochemical gradient with increased numbers of protons in the intermembrane space.  This gradient of protons provides the force to drive Complex V which produces ATP from ADP.
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oh i know this so well,read it for my exam ,ok here it goes:\n    \n\n~ types of cells involved in epiboly are micromeres whereas in emboly ,for involution or rolling in of cells ,the cells involved are micromeres and for ivagination or in pushing of cells,the cells involved are macromeres or megameres.\n\n~ location for the process of epiboly ,in the forming gastrula , is animal zone or pole,whereas for emboly,involution it is equatorial zone and for invagination it is vegetal zone.\n\n~ the germ layer formed after epiboly is the ectoderm and in the case of embol,involution process gives rise to chordamesoderm\nand after the process of invagination,endoderm is formed.\n\n\nim sorry can't write by drawing columns so wrote it this way,hope u understood what i wrote.all the best for ur studies,any help u can contact me! :)
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Reversible phosphorylation has long been an attractive mechanism to control cycles of coat assembly and disassembly during clathrin-mediated endocytosis. Many of the coat proteins are phosphorylated in vivo and in vitro. Our work has focused on the role of phosphorylation of the mu2 subunit of AP-2 (adaptor protein 2), which appears to be necessary for efficient cargo recruitment. Studies to probe the regulation of mu2 phosphorylation demonstrated that clathrin is a specific activator of the mu2 kinase, and, in permeabilized cells, cargo sequestration, driven by exogenously added clathrin, results in elevated levels of m2 phosphorylation. Furthermore, phosphorylated mu2 is mainly associated with assembled clathrin in vivo and its steady-state level is strongly reduced in cells depleted of clathrin heavy chain. Our results imply a central role for clathrin in the regulation of cargo selection via modulation of phospho-mu2 levels. This is therefore a novel regulatory role for clathrin that is independent of its structural role and that provides elegant spatial control of AP-2 and cargo interactions, ensuring that AP-2 is only activated at the correct cellular location and in the correct functional context. Ongoing studies are exploring further the roles of reversible phosphorylation in the coated vesicle cycle.
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the electron transport chain occurs in the inner membrane.  the krebbs cycle occurs in the inner matrix and glycolysis occurs in the cytoplasm of the cell
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The semipermeable membrane that encloses the cytoplasm of a cell.
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Actually, cartilage itself is a type of framework connective tissue.  It serves as a framework for parts that need to be flexible, such as ears.  It also serves as an excellent embryonic skeleton because cartilage can be replaced by bone through cartilage replacement ossification. Ligaments connect bones to bones, not cartilage, and synovial fluid keeps joints from grinding against one another
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Endoplasmic reticulum = 1\nRibosome(s)                 = several\nNucleus                         = 1 but has an inner Nucleolus\nlysosome                      = several\ngolgi bodies                   = I think 1  :)\nmitochondria                 = as u said "mitochondria" & not mitochondrion, so there are several of them\nvacuole                          = several (unlike the plant cell which has one big vacuole)\ncheers
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for internal in external structures and drawings.\nhttp://www.biologymad.com/Kidneys/Kidneys.htm
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Cell Membrane proteins are made inside the cell and inserted into invaginations of the cell membrane called Endoplasmic Reticulum.  At least that's how it works in Eukaryotes (everything from humans and plants to Amoebae).  Prokaryotes (bacteria) must do something similar, but their internal structure is different.\n\nEukaryotes have long stretches of endoplasmic reticilum inside them (but outside the nucleus).  ER is essentially the cell membrane, in long deep convoluted invaginations; it's continuous with the cell membrane but all-but pinched off at the cell surface.\n\nProteins are manufactured by ribosomes (it's a complicated mechanism, but involves the ribosomes anyway) which read the information of mRNA to string amino acids together to make protein.  If the nascent protein chain has the right sequences, its inserted into the ER membrane as it's growing.  As it grows, it pokes through the ER  and out the other side: the "head" of the protein sticks out, while the "tail" is still growing on the inside of the cell.  If the protein has a particular control sequence, called a "stop transfer" sequence, the mechanisms pushing it through the ER stop, and it remains embedded in the ER membrane.  If it doesn't have this sequence, it gets pushed right on through.\n\nWhen the protein is finished, a small pocket of the ER membrane pinches off to form a bubble or "vessicle" inside the cell.  The vessicle membrane will have the new protein embedded in it, with the head of the protein inside the vessicle and the tail sticking out.  If the protein was pushed all the way through, it will be completely inside the vessicle.\n\nThe vessicle is moved to the cell surface by microfibers (a kind of protein called actin that forms fibers that can slide over each other.  It's also found in muscle).  The vessicle fuses with the cell surface and opens up; the "inside" of the vessicle is now the outside of the cell.  The head of the protein, that was on the inside of the vessicle, is now on the outside of the cell, and the tail of the protein is still on the inside, and the cell membrane protein is ready to go.\n\nIf the protein went all the way through the ER, and wound up completely inside the vessicle, then it is secreted (released from, as in a secretion) from the cell when the vessicle fuses with the cell membrane.  You can turn a cell membrane protein into a secretatory protein by removing the "stop transfer" sequence of amino acids from the protein.  This is believed to happen sometimes, for example, when an antibody molecule (a protein) that is embedded in the cell membrane triggers the cell to begin to secrete the same antibody molecule into the blood stream: if something binds to the embedded antibody, the cell begins to manufacture the same molecule but without the stop-transfer sequence, so the cell now secretes antibodies.
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I am making assumptions here, I am presuming that you are talking about biology and are speaking of Reactive oxygen species and the formation of free radicals within the body.\nI hope I am correct. \nReactive oxygen species or ROS are species such as superoxide, hydrogen peroxide, and hydroxyl radical and are associated with cell damage.\n\nFree radicals are also produced inside (and also released towards the cytosol) organelles, such as the mitochondrion. Mitochondria convert energy for the cell into a usable form, adenosine triphosphate (ATP). The process in which ATP is produced, called oxidative phosphorylation, inovolves the transport of protons (Hydrogen ions) across the inner mitochondrial membrane by means of the electron transport chain. In the electron transport chain, electrons are passed through a series of proteins via oxidation-reduction reactions, with each acceptor protein along the chain having a greater reduciton ppotential than the last. The last destination for an electron along this chain is an oxygen molecule. Normally the oxygen is reduced to produce water; however, in about 1-2% of all cases, the oxygen is instead reduced to give the suproxide radical,·O2-. Superoxide needs an additional electron to make it more stable, so it steals an electron from the nearest source, such as: mitochondrial DNA the mitochondrial membrane (called lipid peroxidation), or from protein, or from reductants such as Vitamins C or E, or, from non enzymatic antioxidants such as glutathione or thioredoxin. If too much damage is caused to the mitochondrion, it goes through apoptosis, or programmed cell death.\n\nBcl-2 proteins are layered on the surface of the mitochondria, detect damage, and activate a class of proteins called Bax, which punch holes in the mitochondrial membrane, causing cytochrome C to leak out. This cytochrome C binds to Apaf-1, or apoptotic protease activating factor-1, which is free-floating in the cell’s cytoplasm. Using energy from the ATPs in the mitochondrion, the Apaf-1 and cytochrome C bind together to form apoptosomes. The apoptosomes binds to and activates caspase-9, another free-floating protein. The caspase-9 then cleaves the proteins of the mitochondrial membrane, causing it to break down and start a chain reaction of protein denaturation and eventually phagocytosis of the cell.\n\nAccording to the Free Radical Theory of Aging, aging occurs (via a loss of energy producing cells) either when mitochondria begin to die out because of free radical damage or, when less functional mitochondria remain within these cells. The focus of the project is to neutralize the effect of these free radicals with antioxidants. Antioxidants neutralize free radicals by donating one of their own electrons. The antioxidant nutrients themselves don’t become free radicals by donating an electron because they are stable in either form.\n\nSuperoxide dismutase (SOD) is present in two places naturally in the cell. SOD that is present in the mitochondria contains manganese (MnSod). This SOD is transcribed in the nucleus and has a mitochondrial targeting sequence, thereby localizing it to the miotchondrial matrix. SOD that is present in the cytoplasm of the cell contains copper and zinc (CuZnSod). The genes that control the formation of SOD are located on chromosomes 21, 6, and 4. When superoxide dismutase comes in contact with superoxide, it reacts with it and forms hydrogen peroxide. The stoichiometry of this reaction is that for each 2 superoxide radicals encountered by SOD, 1 H2O2 is formed. This hydrogen peroxide is dangerous in the cell because it can easily transform into a hydroxyl radical (via reaction with Fe2+:Fenton chemistry), one of the most destructive free radicals. Catalase, which is concentrated in peroxisomes located next to mitochondria but formed in the rough endoplasmic reticulum and located everywhere in the cell, reacts with the hydrogen peroxide and forms water and oxygen. Glutathione peroxidase re
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Receptor mediated endocytosis is a process by which cells internalize molecules or viruses. As its name implies, it depends on the interaction of that molecule with a specific binding protein in the cell membrane called a receptor.