wat is cell membrane?
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All biological membranes, including the plasma membrane and the internal membranes of eucaryotic cells, have a common overall structure, they are assemblies of lipid and protein molecules held together by noncovalen interactions. The Lipid molecules are arranged as a continuous double layer 4 to 5 nm thick. This lipid bilayer provides the basic structure of the membrane and serves as a relatively impermeable barrier to the flow of most water- soluble molecules.The proteins molecules are dissolved in the lipid by layer.
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Cytoplasm is the area within the cell inside the plasma membrane (the membrane separate the cell to others) and outside the nucleus (the region contaning genetic materials DNA). Cytoplasm contains many internal organelles (internal structures) that are necessary for cell's functions.\nINternal organelles: Ribosome (needed to make proteins), Golgi complex, lysosomes (digest defective materials in cells, only found in animal cells),Endoplastic Reticulum (2 types: rough with ribosome attached and smooth without ribosome), central vacuole (store H2O, toxins, pigments, waste), Mitochondria (use to make energy for cell, mostly from glucose), chloroplast (needed for photosynthesis in plant cells only),cytoskeleton (connect organelles to each other and membrane, control cell movement, cilia and flagella (cell movements inside an organism).
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Water is actually the main component of the cytoplasm of a cel, as well as being used in energy production cycles.  As a small, non-polar molecule, water enters the cell by way of passive diffusion called osmosis.  The semi-permeable membrane means that not just anything can cross it.  The only things that can passively cross the membrane are molecules that are, like water, small and non-polar.  Anything else must be actively transported in, or have a channel protein.
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Cell membranes are made of lipid bilayers, meaning it is made of a type of fat.  KOH is a strong base that is capable of reacting with the fat in the same reaction that produces soap.  This destroys the lipid bilayer
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The Plasma Membrane (PM) is very important and highly regulated part of the cell. Mainly composed of phospholipids (hydrophobic tails and hydrophilic heads) that are double layered. Also, many other components encompass the PM such as cholesterol (to keep the PM fluid), glycoproteins, and other proteins.\n\nThe PM serves as a major part of the cell's communication pathway. Serves as a barrier for communication with other cells, allows other molecules to anchor on the membrane, allows other cells to attach via cytoskeletal components, makes anchor junctions etc...with other cells.\n\nThink of the PM as the doors and windows of a home (the cell). It is quite important for these parts to be regulated. The doors allows certain people to leave to the home to interact with others, it allows people or items to come inside the home to interact. The windows allow for fresh air to come inside the home which can be regarded as quite essential for survival.
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OSMOSIS IS THE MOVEMENT OF WATER MOLECULES ACROSS THE CELL MEMBRANE.  IF THE OSMOTIC PRESSURE IS HIGH i.e THERE ARE MORE WATER MOLECULES INSIDE THE CELL THEN WATER MOVES OUT TO LESSEN THE PRESSURE.  IF THE OSMOTIC PRESSURE IS VERY LOW THEN WATER MOLECULES MOVE INTO THE CELL TO KEEP THE PRESSURE OUTSIDE AND INSIDE EQUAL.\n\n(IT IS RUDE TO WRITE IN ALL CAPITALS)
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Plant and animal cells are alike in that they both have cell(plasma) membranes, nuclei, and vacuoles. Plant cells are different in that they also contain chloroplasts and cell walls. The vacuoles in plant cells tend to be bigger than in animal cells.
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plasma membrane-bouncer or security\ncell wall-Berlin Wall\nmitochondria-power plant\nER-Ups of the cell\nlysosome-decomposers\nvacuole-water and septic tank\nchloroplast-dye
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Cytoplasm (which consists of cytosol and organelles).
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The cell is the structural and functional unit of all living organisms, and is sometimes called the "building block of life." Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, (humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm, a typical cell mass 1 nanogram).\n\nThe cell theory, first developed in 1839 by Schleiden and Schwann, states that all organisms are composed of one or more cells; all cells come from preexisting cells; all vital functions of an organism occur within cells, and cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.\n\nThe word cell comes from the Latin cella, a small room. The name was chosen by Robert Hooke when he compared the cork cells he saw to the small rooms monks lived in.\n\nAll cells, whether prokaryotic or eukaryotic, have a membrane, which envelopes the cell, separates its interior from its environment, regulates what moves in and out, and maintains the electric potential of the cell. Inside the membrane, a salty cytoplasm takes up most of the cell volume. All cells possess DNA, the hereditary material of genes, and RNA, containing the information necessary to build various proteins such as enzymes, the cell's primary machinery. There are also other kinds of biomolecules in cells.
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Nuclear membrane is formed by a series of  flattened cistenae aligned sideways with gaps called nuclear pores. There are pore complexes guarding the nuclear pores.The flattened cisternae are smooth- surfaced endoplasmic reticulum. It is a typical biological membrane of lipo-protein.\nPlasma membrane is glyco-lipoprotein complex.The overcoat of the plasma membrane is made by the Golgi Complex. It is a complex of carbohydrate side chains along with proteins.The overcoat lies over the bilayer of lipid through with proteins lie across: some  projected,  others buried in the bilayer of lipid. Plasma membrane contains several enzymes and channels connected with transport of ions and small molecular weight substances.
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Ermm, the fact that cells are the smallest building blocks of life is the reason that we see things as they are.\n\nThe basis is that all cells contain life and they make what is specified in their DNA/RNA. Heart cells make hearts, lung cells -> lungs, blood cells -> red or white, skin cells -> skin..you get the idea.\n\nI hope I have answered your question, or at least to a certain extent.
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the nucleus of the cell controls and coordinates all the work of the cell. this takes care of composition.the cell wall and the cell membrane proects the cell
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The nucleus has a membrane and contains the chromosomes which are made from DNA. deoxyribose nucleic acid.
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All the answers are here --> http://en.wikipedia.org/wiki/Cell_%28biology%29\n(and in your book)
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cells dont have cells but they they have organelles which are sort of like cells, which includes mitochondria, ribosomes, golgi apparatus, etc. that have various functions such as converting sugar to energy, synthesizing proteins, etc. they're sort of like minature organs if the cell was your body (hence the name organelles
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In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. If they have only one lipid bilayer, they are called unilamellar vesicles; otherwise they are called multilamellar. Vesicles store, transport, or digest cellular products and wastes.\n\nThis biomembrane enclosing the vesicle is the same as that of the outer cellular membrane. Then, because of the separation, the intravesicular environment can be made to be different from the cytosolic environment. Vesicles are a basic tool of the cell for organizing metabolism, transport, enzyme storage, as well as being chemical reaction chambers. Many vesicles are made in the Golgi apparatus, but also in the endoplasmic reticulum, or are made from parts of the plasma membrane.\n\nMore at http://en.wikipedia.org/wiki/Vesicle_%28biology%29