Membrane Structure and Function
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| 7436422938 | Explain the meaning of the statement that phospholipids and most other membrane constituents are amphipathic molecules. | Most molecules are amphipathic molecules because phospholipids are both hydrophobic and hydrophilic on the bilayer, due to the heads being hydrophilic and tails being hydrophobic. | 0 | |
| 7436422940 | Fluid mosaic model | The structure of biological membranes consists of various proteins that are attached to or embedded in a bilayer of amphipathic phospholipids. | 1 | |
| 7436422941 | Explain how the fluid mosaic model of membrane structure explains each experimental finding: a) Membranes with different functions may differ in type and number of membrane proteins. b) Membrane proteins are not very water-soluble. | A) Each membrane has its own unique complement of membrane proteins, which determine most of the specific functions of that membrane. B) Membrane proteins are not very water-soluble because they are impermeable to most hydrophilic molecules. | 2 | |
| 7436422942 | Integral proteins | Often extend through the membrane (transmembrane), with two hydrophilic ends. The hydrophobic midsection usually consists of one or more alpha helical stretches of hydrophobic amino acids. | 3 | |
| 7436422943 | Peripheral proteins | Attached to the surface of the membrane, often to integral proteins. Attachments of membrane proteins to the cytoskeleton on the cytoplasmic side and fibers of the extracellular matrix on the exterior provide a supportive framework for the plasma membrane. | 4 | |
| 7436422944 | Distinguish between peripheral and integral membrane proteins. | Peripheral: Provides the framework for the plasma membrane and is attached to integral protein. Integral: Go through the membrane with two hydrophilic ends. | 5 | |
| 7436422946 | List six major functions of membrane proteins. | 1. Transport 2. Enzymatic activity 3. Cell-cell recognition 4. Intercellular joining 5. Signal transduction 6. Attachment to the cytoskeleton and extracellular matrix | 6 | |
| 7436422948 | Glycoprotein | A protein with one or more carbohydrates covalently attached to it. | 7 | |
| 7436422949 | Transport protein | A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane. | 8 | |
| 7436422950 | Aquaporin | Facilitate water passage | 9 | |
| 7436422951 | Explain the role of membrane carbohydrates in cell-cell recognition (glycoproteins). | The ability of a cell to distinguish other cells based on recognition of membrane carbohydrates. The glycolipids and glycoproteins attached to the outside of plasma membranes varies. | 10 | |
| 7436422953 | Concentration gradient | A region along which the density of a chemical substance increases or decreases. | 11 | |
| 7436422954 | Passive transport | When the cell does not expend energy when substances diffuse down their concentration gradient. | 12 | |
| 7436422956 | Tonicity | The tendency of a cell to gain or lose water in a given solution, is affected by the relative concentrations of solutes that cannot cross the membrane in the solution and in the cell. | 13 | |
| 7436422960 | Plasma membrane | A selective permeable membrane that permits a regular exchange od nutrients, wate products, oxygen, and inorganic ions. | 14 | |
| 7436422961 | Explain how hydrophobic molecules cross cell membranes. | Cell membranes are made of a lipid bilayer, molecules with hydrophilic heads and hydrophobic tails. These molecules arrange in parallel lines with the tails facing inwards towards each other and the heads facing outwards towards the water. Hydrophobic molecules are drawn into the lipid bilayer, trying to get away from the water. | 15 | |
| 7436422962 | Facilitated diffusion | The diffusion of polar molecules and ions across a membrane with the aid of transport proteins, with either channel proteins or carrier proteins. | 16 | |
| 7436422963 | Ion channel | A transmembrane protein channel that allows a specific ion to flow across the membrane down its concentration gradient. | 17 | |
| 7436422964 | Active transport | Requiring the expenditure of energy to transport a solute against its concentration gradient; essential for a cell to maintain internal concentrations of small molecules that differ from environmental concentrations. The movement of a substance across a cell membrane, with an expenditure of energy, against its concentration or electrochemical gradient; mediated by specific transport proteins. | 18 | |
| 7436422965 | Sodium-potassium pump | Exchanges N+ and K+ across animal cell membranes, creating a higher concentration of potassium ions and lower concentrations of sodium ions within the cell. | 19 | |
| 7436422966 | Membrane potential | A voltage across the plasma membrane due to the unequal distribution of ions. | 20 | |
| 7436422967 | Electrochemical gradient | Combination of chemical force (the ion's concentration gradient) and electrical force (the effect of the membrane potential on the ion's movement). | 21 | |
| 7436422968 | Electrogenic pump | Membrane proteins that generate voltage across a membrane by the active transport o ions. | 22 | |
| 7436422969 | Distinguish between channel proteins and carrier proteins. | Channel proteins: Hydrophobic pathways through a membrane are provided for specific molecules, such as aquaporins, which facilitate water passage. Carrier proteins: Physically bind and transport a specific molecule. | 23 | |
| 7436422970 | Define diffusion. Explain why diffusion is a passive and spontaneous process. | Diffusion: The movement of a substance down its concentration gradient due to random thermal motion. Diffusion is a passive and spontaneous process because one solute is unaffected by the concentration gradients of other solutes and the cell does not expend energy when substances diffuse down their concentration gradient. | 24 | |
| 7436422971 | Explain why a concentration gradient of a substance across a membrane represents potential energy. | The concentration gradient of a substance across a membrane represents potential energy because it drives diffusion. | 25 | |
| 7436422972 | Distinguish between solutions that are hypertonic, hypotonic, and isotonic to cell contents. | Hypertonic: When the cell loses water and shrivels. Hypotonic: When the cell gains too much water, swell, and possibly lyse (burst). Isotonic: Equilibrium; when the cell neither gains or lose water. | 26 | |
| 7436422973 | Define osmosis and predict the direction of water movement based on differences on solute concentrations. | Osmosis: The diffusion if water across a selectively permeable membrane. The direction of water movement based on differences on solute concentrations depends on how the water diffuses down its own concentration. | 27 | |
| 7436422974 | Explain how transport proteins facilitate diffusion. | Transport proteins aids the diffusion of ions and polar molecules to move across the plasma membrane. | 28 | |
| 7436422975 | Distinguish between osmosis, facilitated diffusion, and active transport. | Osmosis: The diffusion if water across a selectively permeable membrane. Facilitated diffusion: The diffusion of polar molecules and ions across a membrane with the aid of transport proteins, with either channel proteins or carrier proteins. Active transport: The movement of a substance across a cell membrane, with an expenditure of energy, against its concentration or electrochemical gradient; mediated by specific transport proteins. | 29 | |
| 7436422976 | Describe the two forces that combine to produce an electrochemical gradient. | Combination of chemical force (the ion's concentration gradient) and electrical force (the effect of the membrane potential on the ion's movement). | 30 | |
| 7436422977 | Explain how an electrogenic pump creates voltage across a membrane. Name two electrogenic pumps. | Active transport and sodium-potassium pump | 31 | |
| 7436422978 | Describe the process of cotransport. | A mechanism through which the active transport of solute is indirectly driven by an ATP-powered pump that transports another substance against its gradient. As that transported substance then diffuses back down down its concentration gradient through a contransporter, the solute is carried against its concentration gradient across the membrane. | 32 | |
| 7436422979 | How are large molecules are transported across a cell membrane? | The process of exocytosis secretes large molecules by the fusion of vesicles with the plasma membrane. | 33 | |
| 7436422980 | Distinguish between exocytosis and receptor-mediated endocytosis. | Exocytosis: The cell secretes large molecules by the fusion of vesicles with the plasma membrane. Receptor-mediated endocytosis: Allows a cell to acquire specific substances from extracellular fluid. | 34 | |
| 7436422985 | Receptor-mediated endocytosis | Allows a cell to acquire specific substances from extracellular fluid. | 35 | |
| 7436422986 | Ligands | Molecules that bind specifically to receptor sites, attach to proteins usually clustered in coated pits on the cell surface and are carried into the cell when a vesicle forms. | 36 | |
| 7436422987 | Proton pump | Transports H+ out of the cell generates voltage across membranes on plants, fungi, and bacteria. | 37 | |
| 7436422988 | polymer | A long molecule consisting of many similar or identical monomers linked together | 38 | |
| 7436422989 | monomer | The subunit that serves as the building block of a polymer | 39 | |
| 7436422990 | double helix | The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape | 40 | |
| 7436422991 | RNA | A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses | 41 | |
| 7436422992 | DNA | A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins | 42 | |
| 7436422993 | condensation reaction | A reaction in which two molecules become covalently bonded to each other through the loss of a small molecule, usually water; also called dehydration reaction | 43 | |
| 7436422994 | dehydration reaction | A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule | 44 | |
| 7436422995 | starch | A storage polysaccharide in plants consisting entirely of glucose | 45 | |
| 7436422996 | glycogen | An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch | 46 | |
| 7436422997 | nucleotide | The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous bas and a phosphate group | 47 | |
| 7436422998 | monosaccharide | The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, the molecular formulas of monosaccharides are generally some multiple of CH20 | 48 | |
| 7436422999 | fatty acid | a long carbon chain carboxylic acid. fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat | 49 | |
| 7436423000 | steroid | a type of lipid that consists of four carbon rings to which various functional groups are attached | 50 | |
| 7436423001 | cholesterol | A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids | 51 | |
| 7436423002 | polysaccharide | A polymer of up to over a thousand monosaccharides, formed by condensation reactions | 52 | |
| 7436423003 | carbohydrate | A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides). | 53 | |
| 7436423004 | triacylglycerol | Three fatty acids linked to one glycerol molecule | 54 | |
| 7436423005 | nucleic acid | A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA | 55 | |
| 7436423006 | gene | A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses) | 56 | |
| 7436423007 | disaccharide | A double sugar, consisting of two monosaccharides joined by dehydration synthesis | 57 | |
| 7436423008 | hydrolysis | A chemical process that lyses, or splits, molecules by the addition of water; an essential process in digestion | 58 | |
| 7436423009 | lipid | One of a family of compounds, including fats, phospholipids, and steroids, that are insoluble in water | 59 | |
| 7436423010 | alpha helix | A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure | 60 | |
| 7436423011 | pyrimidine | one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring. Cytosine (C), thymine (T), and uracil (U) | 61 | |
| 7436423012 | ribose | The sugar component of RNA | 62 | |
| 7436423013 | cellulose | A structural polysaccharide of cell walls, consisting of glucose monomers joined by b-1, 4-glycosidic linkages | 63 | |
| 7436423014 | chitin | A structural polysaccharide of an amino sugar found in many fungi and in the exoskeletons of all arthropods | 64 | |
| 7436423015 | peptide bond | the covalent bond between two amino acid units, formed by condensation synthesis | 65 | |
| 7436423016 | beta pleated sheet | One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds | 66 | |
| 7436423017 | purine | a nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine | 67 | |
| 7436423018 | protein | A three-dimensional biological polymer constructed from a set of 20 different monomers called amino acids | 68 | |
| 7436423019 | polypeptide | A polymer (chain) of many amino acids linked together by peptide bonds | 69 | |
| 7436423020 | amino acid | An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of proteins | 70 | |
| 7436423021 | primary structure | the level of protein structure referring to the specific sequence of amino acids | 71 | |
| 7436423022 | cell | -the simplest collection of matter that can live -bound by plasma membrane -contains chromosomes | 72 | |
| 7436423023 | Light Microscope | -magnifies effectively but has resolution issues -commonly used in lab -good for study of live cells -limited by the shortest wavelength of light used to illuminate the specimen | 73 | |
| 7436423024 | magnification | ration of the object's image size to its real size | 74 | |
| 7436423025 | resolution | a measure of the clarity of the image; the minimum distance two points can be separated and still be distinguished | 75 | |
| 7436423026 | Electron Microscope | -focuses a beam of electrons through the specimen or into it's surface -have much shorter wavelengths than the wavelengths of visible light -reveals cell's ultrastructure -2 kinds *scanning *transmission | 76 | |
| 7436423027 | Scanning Electron Microscope | provides a 3D image (microscope) | 77 | |
| 7436423028 | Transmission Electron Microscope | -good for study of ultrastructure -uses energy beam -cannot look at living things | 78 | |
| 7436423029 | cytosol | semi fluid within the membrane | 79 | |
| 7436423030 | prokaryotic cell | -no nucleus -organisms of the domains bacteria and archaea -has nucleoid | 80 | |
| 7436423031 | nucleiod | Region of prokaryotic cells where DNA is located | 81 | |
| 7436423032 | cell wall | Plant Organelle: ridged outermost cell layer, made of cellulose, provides a sturdy area where cell can thrive | 82 | |
| 7436423033 | eukaryotic cell | -true nucleus -protist, fungi, animal and plants -membranous nuclear envelope -bigger than prokaryotic cells | 83 | |
| 7436423034 | cytoplasm | the entire region between the nucleus and the plasma membrane | 84 | |
| 7436423035 | plasma membrane | functions as a selective barrier that allows passage of oxygen, nutrients, and wastes to service the entire volume of the cell | 85 | |
| 7436423036 | membrane | fundamental to the organization of the cell - generally consists of a double layer of phospholipids and other molecules (cholesterol, glyoproteins and glycolipids) | 86 | |
| 7436423037 | central vacuole | storage unit (one of the largest in the cell) in plants to store water | 87 | |
| 7436423038 | plasmodesmata | holes in the cell wall allowing entrance/exit from/to the cell | 88 | |
| 7436423039 | nuclear envelope | encloses nucleus separating its contents from the cytoplasm the membrane is a lipid bilayer | 89 | |
| 7436423040 | pore complex | intricate protein structure that regulates the entry and exit of certain large macromolecules and particles | 90 | |
| 7436423041 | nuclear lamina | -lines nuclear side of envelope near the pores -net-like array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope | 91 | |
| 7436423042 | chromosomes | structures that carry genetic info made of chromatin | 92 | |
| 7436423043 | chromatin | a complex array of proteins and DNA coiled together | 93 | |
| 7436423044 | nucleolus | a structure in the nucleus formed from various chromosomes -active in synthesis of ribosomes | 94 | |
| 7436423045 | ribosomes | organelles that carry out protein synthesis -2parts *large subunit *small subunit -2 locations *free *bound | 95 | |
| 7436423046 | free ribosomes | suspended in cytosol, makes whatever the cell needs | 96 | |
| 7436423047 | bound ribosomes | attached to the outside of the endoplasmic reticulum or nuclear envelope - makes specific proteins | 97 | |
| 7436423048 | peroxisome | Organelle: uses enzymes to get rid of the metabolic wastes specifically hydrogen peroxide (numerous in the liver) | 98 | |
| 7436423049 | mitochondria | Organelle: (power plant of the cell) takes organic material and turns it into ATP, can be thousands in a single cell | 99 | |
| 7436423050 | lysosome | Organelle: aids in waste removal system of cells, puts dead bacteria, organelles, and other matter into a vacuole and fills it with digestive enzymes | 100 | |
| 7436423051 | golgi apparatus | Organelle: "Fedex" of the cell. accepts the proteins, sorts them and then sends them where they need to go | 101 | |
| 7436423052 | Smooth Endoplasmic Reticulum | Organelle: produces lipids, metabolizes carbohydrates and concentrates calcium (makes phospholipids) | 102 | |
| 7436423053 | Rough Endoplasmic Reticulum | Organelle: studded with ribosomes, makes transport proteins for the plasma membrane | 103 | |
| 7436423054 | Ribosomes on ER | take info from mRNA, make proteins according to what the RNA says | 104 | |
| 7436423055 | centrioles | Organelle: forms spindles that aid in the cellular division process, they grab chromosomes and separate them, only in animal cells | 105 | |
| 7436423056 | centrisome | Organelle: creates microtubules | 106 | |
| 7436423057 | cytoskeleton | Organelle: internal framework of the cell 3 Parts *microfilaments *intermediate filaments *microtubules | 107 | |
| 7436423058 | microfilaments | thin but solid protein in cytoplasm of most eukaryotic cells | 108 | |
| 7436423059 | intermediate filaments | thicker than microfilaments, used more for structure | 109 | |
| 7436423060 | microtubules | hollow but thick tube of protein in the cytoplasm of all eukaryotic cells and in cilia, flagella and cytoskeleton | 110 | |
| 7436423061 | microvilli | Organelle: increases surface area, found in intestines and kidneys | 111 | |
| 7436423062 | chloroplast | Plant Organelle: houses photosynthesis, produces ATP for the cell (similar to mitochondria) | 112 | |
| 7436423063 | tonoplast | Plant Organelle: membranes that enclose the central vacuole | 113 | |
| 7436423064 | central vacuole | Plant Organelle: enclosed sac found in mature plant cells, used for storage, breakdown of waste products and hydrolysis of macromolecules | 114 | |
| 7436423065 | Selective Permeability | -Allows some substances to cross more easily than others -Gives cell the ability to discriminate in its chemical exchanges | 115 | |
| 7436423066 | Plasma Membrane | -Blocks bad things from coming inside of the cell -Allows good things to pass through -Maintains homeostasis -Selectively permeable -Separate external environment from internal environment | 116 | |
| 7436423067 | Amphipathic | -Molecules that have a hydrophilic region and a hydrophobic region -Ex: Phospholipids | 117 | |
| 7436423068 | Gorter and Grendel Theory | -Cell membranes must be phospholipid bilayers -Double layer is a stable boundary due to the exposure of hydrophilic heads to water and the shelter of hydrophobic tails -Inaccuracies: surface of a membrane with pure phospholipids adheres less strongly to water than the surface of a biological membrane | 118 | |
| 7436423069 | Davson and Danielli Theory | -Phospholipid bilayer between two layers of proteins (sandwich model) -Inaccuracies: generalized that all cell membranes are identical (membranes with different functions differ in chemical composition), membrane proteins not soluble in water because they are amphipathic | 119 | |
| 7436423070 | Singer and Nicolson Theory | -Membrane proteins dispersed and individually inserted into the phospholipid bilayer with the hydrophilic regions protruding -Inaccuracies: membranes are more mosaic than fluid and membrane contains more proteins | 120 | |
| 7436423071 | Freeze Fracture Technique | -Splits a membrane along the middle of a phospholipid bilayer -Under a microscope, the interior appears cobblestoned with protein particles interspersed in the smooth matrix | 121 | |
| 7436423072 | Fluidity of a Cell's Membrane | -Maintained by hydrophobic interactions -These interactions cause lipids and porteins to shift laterally -Regulated by temperature -Not all parts of the membrane are equally fluid -Saturated --> single bonds --> straight tails --> pack more tightly --> less fluidity -Unsaturated --> double bonds --> bends in tail --> looser packing --> greater fluidity | 122 | |
| 7436423073 | Fluid Mosaic Model | -Phospholipids make a membrane fluid -Mosaic of protein islands embedded in it, floating and moving around -Overwhelmingly phospholipid, forming a relatively fluid-like substance | 123 | |
| 7436423074 | Membrane Composition | -Two phospholipid tails made up of fatty acids -Tails move away from water -Phosphate based head faces away from the aqueous part of the cell -Spontaneous physical process | 124 | |
| 7436423075 | Phospholipid Bilayer | -Tails facing each other creates a bilayer -Hydrophobic (nonpolar) tails attract and face each other in middle -Hydrophilic (polar) heads face outside of membrane | 125 | |
| 7436423076 | Changes in Fluidity | -When temperature increases, it stays fluid for a longer amount of time -When cholesterol decreases, fluidity increases -Cholesterol acts as a temperature buffer -When unsaturated hydrocarbons increase, they prevent molecules from packing closely together, which enhances fluidity | 126 | |
| 7436423077 | Effects of Cholesterol on Membrane Fluidity | -At warm temperatures, it restrains movement of phospholipids -At cool temperatures, it maintains fluidity by preventing tight packing -Four ring structure adds kinks to the membrane | 127 | |
| 7436423078 | Extracellular Matrix | -Interlocking mesh of fibrous proteins -Collagen, the most abundant protein in our body, makes it stiff -Cell to cell adhesion -Sends cell signals -Senses changes in local environment -Tells cell to change behavior -Active in cancers and tumors |  | 128 |
| 7436423079 | Integral Proteins | -Penetrate hydrophobic core of the lipid bilayer -Pass all the way through the membrane -Includes nonpolar amino acids | 129 | |
| 7436423080 | Peripheral Proteins | -Not embedded in the lipid bilayer -Only on one side -Found on edges of the bilayer -Loosely bound to the surface | 130 | |
| 7436423081 | Types of Membrane Proteins | -Transport -Enzymatic -Signal -Cell-Cell recognition -Intercellular joining -Attachment to cytoskeleton and ECM | 131 | |
| 7436423082 | Transport Protein | -Allows molecules to pass through the membrane -Provides hydrophilic channel across a membrane -Shuttles a substance from one side to another by changing shape -Includes ions and polar molecules | 132 | |
| 7436423083 | Enzymatic Activity Protein | -Active site exposed to substances in adjacent solution -Carries out steps of metabolic pathway | 133 | |
| 7436423084 | Signal Transduction Protein | -Binding site with chemical messenger -External messenger causes a shape change in the protein that relays message to the inside of a cell | 134 | |
| 7436423085 | Cell-Cell Recognition Protein | -Identification tags that are recognized by the membranes of other cells | 135 | |
| 7436423086 | Intercellular Joining Protein | -Proteins of adjacent cells hook together in junctions | 136 | |
| 7436423087 | Attachment to the Cytoskeleton and ECM Protein | -Microfilaments noncovalently bond to membrane proteins, maintaining cell shape and stabilizing location of proteins -Mostly structural but still involve communication | 137 | |
| 7436423088 | Glycoproteins and Glycolipids | -Distinguish neighboring cells from one another -Organ and tissue development -Rejection of foreign cells by immune system | 138 | |
| 7436423089 | Glycolipids | -Membrane carbohydrates covalently bonded to lipids | 139 | |
| 7436423090 | Glycoproteins | -Membrane carbohydrates covalently bonded to proteins | 140 | |
| 7436423091 | Permeability and Transport | -Hydrophobic molecules can penetrate -Hydrophilic ionic, and large molecules cannot penetrate -Channel proteins allow hydrophilic molecules to pass through -Aquaporins allow water to pass through -Carrier proteins have specific shape to match the molecules they transport | 141 | |
| 7436423092 | Channel Proteins | -Contain a hydrophilic channel that certain molecules or atomic ions can use as a tunnel through the membrane -Ex: aquaporins | 142 | |
| 7436423093 | Carrier Proteins | -Hold onto passengers and change shape in a way that shuttles them across the membrane | 143 | |
| 7436423094 | Membrane Sidedness | -Two lipid layers vary in lipid composition and each protein has a directional orientation in the membrane -Molecules that start on the inside face of the ER end up on the outside face of the plasma membrane -Determined by the ER and Golgi | 144 | |
| 7436423095 | Aquaporins | -Allow entry of water molecules into the membrane -Allows water to permeate the membrane | 145 | |
| 7436423096 | Diffusion | -Movement of molecules of any substance so that they are spread out evenly into the available space -Movement from an area of high concentration to an area of low concentration -A form of passive transport because the cell does not have to use energy to make it happen -Ordered and well structured to less ordered -Occurs spontaneously | 146 | |
| 7436423097 | Active Transport | -Movement of molecules opposite the direction of diffusion -More ordered and structured molecules requires the addition of energy -Pushes things opposite of the way they move naturally -Movement from low concentration to high concentration -Includes the Sodium Potassium pump and the Proton pump | 147 | |
| 7436423098 | Concentration Gradient | -Potential energy | 148 | |
| 7436423099 | Free Water Concentration | -Driving force in osmosis -Water diffuses across the membrane from the region of lower solute concentration until the solute concentrations on both sides of the membrane are equal | 149 | |
| 7436423100 | Water Balance in Cells Without a Wall (Animal Cells) | -In an isotonic environment, there is no water movement across the membrane -Cell loses water to surroundings in a hypertonic environment -Cell will lyse in a hypotonic environment -Cannot tolerate to little or too much water -Needs osmoregulation |  | 150 |
| 7436423101 | Water Balance in Cells With a Wall (Plant Cells) | -Hypotonic solution maintains water balance (turgid) -Isotonic: flaccid -Hypertonic causes the cell to shrivel (plasmolyze) | 151 | |
| 7436423102 | Facilitated Diffusion | -Polar/ionic molecules impeded by the lipid bilayer of membrane diffuse passively with the help of transport proteins that span the membrane | 152 | |
| 7436423103 | Ion Channels | -Stimulus allows for transport | 153 | |
| 7436423104 | Gated Channels | -Open/close in response to stimulus | 154 | |
| 7436423105 | Active Transport and ATP | -Transfers the terminal phosphate group directly to the transport protein -Induces protein to change shape -Ex: sodium potassium pump exchanges sodium for potassium across the plasma membrane | 155 | |
| 7436423106 | Membrane Potential | -Voltage (electrical potential energy) across a membrane -Ranges from -50 to -200 millivolts | 156 | |
| 7436423107 | Electrochemical Gradient | -Combination of chemical force (ion's concentration gradient) and electrical force (effect of membrane potential on ion's movement) -Drive the diffusion of ions across a membrane | 157 | |
| 7436423108 | Electrogenic Pump | -Transport protein that generates voltage across a membrane | 158 | |
| 7436423109 | Proton Pump | -Transports hydrogen ions (protons) out of the cell -Transfers positive charge from cytoplasm to the extracellular solution -Pushes the ions against their gradient | 159 | |
| 7436423110 | Sodium Potassium Pump | 1. Cytoplasmic Na+ binds to the sodium-potassium pump, high affinity for Na+ due to shape 2. Na+ binding stimulates phosphorylation (addition of phosphate group) of a protein added by ATP 3. Phosphorylation causes protein to change shape, decreasing affinity for Na+ 4. High affinity for K+ due to new shape, which binds to extracellular side and triggers release of phosphate group 5. Loss of phosphate restores protein's original shape, which has a lower affinity for K+ 6. K+ is released and affinity for Na+ is high again, repeating the cycle |  | 160 |
| 7436423111 | Passive Transport vs. Active Transport |  | 161 | |
| 7436423112 | Cotransport | -Single ATP powered pump that transports a specific solute that indirectly drives the active transport of several other solutes -Plants use gradient of H+ generated by proton pumps to drive active transport of amino acids, sugars, and other nutrients into the cell -Helps decrease instances of dehydration in humans | 162 | |
| 7436423113 | Ligand | -Molecule that binds to a receptor site of another molecule | 163 | |
| 7436423114 | Exocytosis | -Transport vesicles fuse with membrane and dump contents outside -Movement out of the cell | 164 | |
| 7436423115 | Pinocytosis | -Cellular drinking -Cell gulps droplets of extracellular fluid into tiny vesicles | 165 | |
| 7436423116 | Phagocytosis | -Cellular eating -Cell engulfs particle by wrapping it with a thin membrane enclosed sack | 166 | |
| 7436423117 | Endocytosis | -Cell acquires bulk quantities of specific substances -Forms new vesicles from plasma membrane -Movement into the cell | 167 | |
| 7436423118 | Receptor Mediated Endocytosis | -Ligands bind to receptor proteins | 168 | |
| 7436423119 | Osmosis | -DIffusion of water through a membrane from high solute to low solute -More solute means less water molecules -Diffuse from where they are abundant to where they are scarce | 169 | |
| 7436423120 | Hypertonic | -More solute outside the cells | 170 | |
| 7436423121 | Hypotonic | -Less solute outside the cell | 171 | |
| 7436423122 | Isotonic | -Equal solute concentration inside and outside the cell | 172 | |
| 7436423123 | Osmoregulation | -Balancing water uptake and loss -Controlling water flow into and out of the cell | 173 | |
| 7436423124 | Water Potential | -Water moves from area of high water potential to areas with low water potential -Free energy of water -Explains movement of water from the roots to the top of a tree | 174 |
