Biology Chapter 7
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Created by:
MSeriynneM Plus on October 23, 2012
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Campbell Biology Chapter 7 flash cards
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49 terms
Terms | Definitions |
|---|---|
 What is the function of a cell membrane? | 1) seperates cell from its surroundings 2) exhibits selective permeability 3) forms additional compartments in eukaryotic cells |
| What is the cell membrane mostly made up of? | lipids and proteins, although some carbs made up of phospholipids in a bilar |
| What is the fluid mosaic model? | -in phospholipid bilaer, proteins embed in it -switch laterally all the time -flip flop less (maybe once a month) -is fluid until temperatures are very low. Then it solidifies |
| What is the purpose of cholesterol? | temperature buffer in cold temperatures, prevents from packing together and freezing warm temperature, reduces membrane fluidity because cholesterol is rigid in the membrane |
| Do proteins move also? | YES! (think hybrid mouse cell) |
| What are the two integral trans membrane protein types?> | integral proteins peripheral proteins |
| Integral proteins are | proteins that penetrate hydrophobic core of lipid bilaer some span entire membrane, usually alpha helices, stick out in one part center is hydrophobic, top and bottom hydrophilic |
| peripheral proteins are | proteins that are inside or outside of membrane, attached to integral proteins on cytoplasmic side, held in place by cytoskeleton on ECM, attached to integrins (fibers) |
| What are the six major functions of membrane proteins | 1) transport - if protein spans across entire membrane, may procide hydrophilic channel that is selective for particular molecule/route 2)catalyze chemical reactions 3) signal transduction 4) recognition 4) intercellular connections - hook into various junctions 5) connections to cytoskeleton and ECM |
| What is signal transduction? | proteins accept chemical messengers from other cells (i.e. hormones) |
| What is recognition? | identifies the cell as belonging to a specific type (tagged with carbohydrates, distinguises self from non self |
| What is the membrane naturally permeable to? | -nonpolar molecules -small molecules (oxygen, carbon dioxide, hydrocarbons) -glucose and other sugars pass slowly through a lipid bilaer |
| Is the membrane permeable to water? | somewhat but very slow - get stuck in hydrophobic middle |
| Is the membrane permeable to polar molecules? | Very rarely |
| Is the membrane permeable to ions or charged particles? | No |
| Which two particular protein types help transport across lipid bilayer? | Channel proteins Carrier proteins |
| channel proteins are | integral proteins that have hydrophilic tunnel through membrane that selectively allows certain polar ions to go through i.e. aquaporin |
| carrier proteins are | integral proteins that hold on to their passengers and change their shape to shuttle them across the membrane |
| what is passive transport? | movement across membrane that requires no energy. It could be simple diffusion or facilitated transport. |
| What is diffusion? | Movement of molecules from high concentration gradient to low concentration gradient this happens naturally, the gradient itself is potential energy |
| What does diffusion do? | tend to equalize solute on both sides of membrane |
| What is osmosis? | Diffusion of solvent, in biology, water, across a semipermeable membrane down its concentration gradient. Because its solvent it usually goes to where there is MORE solute (the hypertonic solution). |
| What is tonicity? | ability of a solution to cause a cell to gain or lose water, depending on the conentration of the nonpenetrating solute inside and out of the cell and the FREE water in the cell |
| Isotonic | solute concentration the same inside and out animal cells like this plant cells are flaccid |
| hypotonic | solute outside is SMALLER than inside, so there is net flow of water in. animal cells lyse plant cells love it - they are turgid. don't burst because of cell wall |
| hypertonic | solute outside greater than inside, water flows OUT animal cells shrink plant cells plasmolyze |
| A solution that has relatively high solute and low free water is | hypertonic |
| a solution that has relatively low solute and high free water is | hypotonic |
| A solution that has equal solute and equal free water | isotonic |
| Movement of water in U tube |  solution at left side of U is hypotonic because it hass less solute. Right is hypertonic. Water wil flow from hypotonic to ypertonic, causing water to rise. |
| Water moves by osmosis from the ___ solution into the ___ solution | Water moves from hypotonic into hypertonic. Concentration of water is greater in hypotonic than in hypertonic (moves down its concentration gradient). |
| Osmoregulation | in animal cells with no cell wall, they need to regulate their water internally, hence contractile vacuole |
| If diffusion is aided by channel and carrier proteins and solute STILL going down concentration gradient, this is known as | facilitated diffusion |
| diffusion in channels | aquaporins - always down a concentration gradient ion channels happens VERY quickly millions/sec |
| Diffusion in carriers | Carrier proteins are also used for active transport but if going down concentration gradient, this is passive (no ATP). happens more slowly, 10/s |
| Active transport is | the use of ATP to move solutes AGAINST concentration gradient. It is always done by carrier proteins. |
| What allows cell to maintain internal concentrations of small solutes different from concentrations in its environment? | Active transport via carrier protiens. |
| What is an example of active transport? | Sodium/Potassium pump: creates electrogradient by moving 3Na+ out of cell and 2Ka+ into cell (net -1 in membrane). |
| how does the sodium potassium pump work? | 1 - pump first binds to Na+. 2 - ATP comes along, "phosphorylates" pump, pumo changes shape. 3 - pump then releases Na+ to outside 4 - pump now open out, only has configuration to fit K+. Pump binds K+. 5 - Pump reverts back to original conformation (like a spring bottle, no atp needed this way) and releases K+ into cell, ready to start again. |
| When open to ECM, only what can go into sodium potassium pump? | 2K+ |
| When open to cytoplasm, only what can go into Na+/K+ pump? | 3Na+ |
| How large is the voltage across membrane? | -50 to -200 mV -negative voltage inside cell, positive outside |
| How do ions react to potential of membrane? | Negative ions are attracted to positive voltage outside of cell, want to leave positive ions are attracted to negative voltage inside of cell, wnat to enter Hence why ions are affected by electrochemical gradient |
| What are the two types of bulk transport mechanisms? | -exocytosis - kick out -endocytosis - eat |
| Exocytosis | -cell releases substances to outside, milk, proteins, wastes -happens via versicles |
| Endocytosis | ingest food or liquid for feeding or defense -phagocytosis -pinocytosis -recepter mediated endocytosis |
| Phagocytosis | -ingests particles -cell membrane forms pseudopods (from microfilaments) infolds, and engulfs this is NOT specific |
| Pinocytosis | ingets liquids much smaller folding in takes liquids and issolved particles |
| REcepter mediated endocytosis | is specific REcepters in ECM/membrane. substances pass, recepter binds them. Cell knows it has to pick them up, so in folds in and brings them in. -this takes a lot of energy so cells do this very little (for example when they see a lot of cholesterol, they take in) |
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