3.1 BIOLOGICAL MEMBRANES 3.1.1 Properties of Cell Membranes • Separates living cell from its nonliving surroundings. • 8 nm thick. • Selectively permeable - allows some substances to cross more easily than others. 4.1.2 Fluid Mosaic Model • Singer and Nicolson (1972) - plasma membrane is a mosaic of proteins dispersed within lipid bilayer‚ with only bilayer‚ the hydrophilic regions exposed to water. Hydrophilic region of protein Phospholipid bilayer Hydrophobic region of protein
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and it’s wrapped around my candy. The cellophane wrap is one of the most versatile discoveries of the 1900s. Intended to be a protective textile‚ the cellophane has since found application in many industries as a packaging material and as a semi-permeable film. Many people mistake cellophane for plastic. The truth is the two materials are of completely different composition. Plastic is a synthetic or
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Although the thickness of the cell membrane is only 5-10nm‚ it is a physical barrier to the movement of ions and molecules. The cell membrane and other membranes within a cell are all living membranes that exhibit selective permeability. A selectively permeable membrane enables molecules of certain substances to move across it freely while excluding others. By responding to changing environmental conditions or cellular needs‚ a cell membrane may also be a barrier to a substance at one time and then actively
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Human Biology Unit 1 Assignment. A cell is a small membrane enclosed structure filled with an aqueous solution where the organelles are found. Organelles are small structures within cells that perform dedicated functions. All eukaryotic cells have the following organelles: Nucleus‚ Ribosomes‚ Lysosomes‚ Cytoplasm‚ Nucleolus‚ Cell Membrane‚ Mitochondria‚ Endoplasmic Reticulum (ER) and Golgi Body. Insulin is a protein compound made up of more than one chain of amino acids. Amino acids are the building
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Title: Homeostasis Date: 19th January 2010 Aim: To observe‚ draw and label the parts of a nephron. Apparatus: Slide of the transverse section of a kidney Pencil Paper Microscope Method: The slide of the transverse section of a kidney was mounted on the microscope and observed under high power. Drawings of the parts of the nephron were made. Calculations of Magnification: Loop of Henle One Ocular Division = 0.22 µm Size of Specimen = 2 ocular divisions Conversion of Ocular
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Formation of Hydrocarbons Types of hydrocarbons Parameters for hydrocarbon accumulation Phases of alteration of organic matter Types of kerogen Migration of hydrocarbons Five Major Types of Hydrocarbons Kerogen: Kerogen is a fine-grained‚ amorphous organic matter. It is not soluble to normal petroleum solvents‚ like carbon disulfide. Its chemical composition is 75% C‚ 10% H‚ 15% other (sulfur‚ oxygen‚ nitrogen‚ etc.). It is very important in the formation of hydrocarbons because it is what generates
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form of diffusion in which water diffuses through a selectively permeable membrane from a region of high concentration to a region of lower concentration. This form of diffusion takes place when the molecules in high concentration are too large to move through the membrane. Three factors that determine cell membrane permeability are shape‚ size‚ and polarity. For this experiment‚ it must be kept in mind that sucrose is not permeable to the cell membrane‚ for it is too large to pass through. The cell
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Lab Report #1 Introduction A cell’s plasma membrane is known to be selectively permeable. This implies that the membrane is selective on what substances can pass in and out of the cell. There are two methods of transport that occur through the plasma membrane. One method of transport is called active process which uses ATP energy to transport substances through the membrane. The other method is called passive process which does not require the use of ATP energy. During passive processes
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longer transport calcium out of the cell‚ and intracellular calcium levels get too high. 5. The presence of calcium triggers the release of the excitatory amino acid neurotransmitter glutamate. 6. Glutamate stimulates AMPA receptors and Ca++-permeable NMDA receptors‚ which open to allow more calcium into cells. 7. Excess calcium entry overexcites cells and causes the generation of harmful chemicals like free radicals‚ reactive oxygen species and calcium-dependent enzymes such as calpain‚ endonucleases
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The green tree frog has some environmental adaptations. It possesses the ability to camouflage‚ which will protect it from predators. This is the frog’s main way of protecting itself from predators. The tree frog also has selective hearing and permeable skin which both help it excel in its habitat. The green tree frog breeds from March to October in southern areas and from April to September in northern areas. Usually breading follows a heavy rainfall. When it is time for breading to begin large
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