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Description
Flashcards by Kyannah Harris, updated more than 1 year ago
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Created by Kyannah Harris
almost 5 years ago
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| Question | Answer |
| Fluid Mosaic Model | Membrane's structure-diverse protein molecules suspended in a fluid phospholipid bilayer |
| Selective Permeability | A property pf biological membranes that allows them to regulate the passage of substances across them |
| Identify six different types of functions of proteins in a plasma membrane. | 1) Attachment to the cytoskeleton & ECM 2) Signal reception and relay 3) Enzymatic activity 4) Cell-cell recognition 5) Inter-cellular joining 6) Transport |
| In the origin of a cell, why would the formation of a simple lipid bilayer membrane not be sufficient? What else would have to be part of such a membrane? | The membrane would need embedded proteins that could regulate the movement of substances into and out of the cell. |
| Diffusion | The tendency for particles of any substance to spread out into the available space |
| Concentration Gradient | A region along which the density of a chemical substance increases or decreases |
| Why is diffusion across a membrane called passive transport? | The cell does not expend energy to transport substances that are diffusing down their concentration gradients. |
| Passive Transport | The diffusion of a substance across a biological membrane, with NO expenditure of energy |
| Osmosis | The diffusion of water across a selectively permeable membrane |
| Predict the net water movement between two solutions—a 0.5% sucrose solution and a 2% sucrose solution—separated by a membrane not permeable to sucrose. | Water will move from the 0.5% sucrose solution (lower solute concentration) to the 2% sucrose solution (higher solute concentration). |
| Tonicity | The ability of a surrounding solution to cause a cell to gain or lose water |
| Isotonic | A solution that, when surrounding a cell, causes no net movement of water into or out of the cell |
| Hypotonic | Causes the cell to take up water |
| Hypertonic | Causes the cell to lose water |
| Osmoregulation | The homeostatic maintenance of solute concentrations and water balance by a cell or organism |
| Facilitated Diffusion | The passage of a substance through a specific transport protein across a biological membrane down its concentration gradient |
| Aquaporin | A transport protein in the plasma membrane of an animal, plant, or microorganism cell that facilitates the diffusion of water across the membrane (Osmosis) -ONLY allow water to pass through them |
| How do transport proteins contribute to a membrane’s selective permeability? | Because they are specific for the solutes they transport, the numbers and kinds of transport proteins affect a membrane’s permeability to various solutes. |
| Active Transport | The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins & requiring an input of energy (often as ATP) |
| Cells actively transport Ca2+ out of the cell. Is calcium more concentrated inside or outside of the cell? Explain. | Outside: Active transport moves calcium against its concentration gradient. |
| Exocytosis | The movement of materials out of a cell by the fusion of vesicles with the plasma membrane |
| Endocytosis | Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane |
| Phagocytosis | Cellular "eating"; a type of endocytosis in which a cell engulfs macromolecules, other cells, or particles into its cytoplasm |
| Receptor-Mediated Endocytosis | The movement of specific molecules into a cell by the infolding of vesicles containing proteins with receptor sites specific to the molecules being taken in |
| As a cell grows, its plasma membrane expands. Does this involve endocytosis or exocytosis? Explain. | Exocytosis: When a transport vesicle fuses with the plasma membrane, its contents are released and the vesicle membrane adds to the plasma membrane. |
| Energy | The capacity to cause change, especially to do work |
| Kinetic energy | The energy of motion |
| Thermal energy | A type of kinetic energy associated with the random movement of atoms or molecules |
| Heat | Thermal energy in transfer from one object to another |
| Potential energy | Energy that matter possesses as a result of its location or structure |
| Chemical energy | The potential energy available for release in a chemical reaction |
| Thermodynamics | The study of energy transformations that occur in a collection of matter |
| First Law of Thermodynamics | The energy in the universe is constant; a.k.a. the law of energy conservation |
| Entropy | A measure of disorder, or randomness |
| Second Law of Thermodynamics | Every energy conversion increases the entropy (disorder) of the universe |
| An illustration of the two laws of thermodynamics: transformation of energy and increase in entropy | |
| Cellular Respiration | The energy-releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form that cells can use to perform work |
| How does the second law of thermodynamics explain the diffusion of a solute across a membrane? | Diffusion across a membrane results in equal concentrations of solute, which is a more disordered arrangement (higher entropy) than a high concentration on one side and a low concentration on the other. |
| Exergonic Reaction | Releases energy (exergonic means “energy outward”) |
| Endergonic Reactions | Require a net input of energy and yield products that are rich in potential energy (endergonic means “energy inward”) |
| Metabolism | The total of an organism’s chemical reactions |
| Metabolic Pathway | A series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds |
| Energy Coupling | In cellular metabolism, the use of energy released from exergonic reactions to drive endergonic reactions |
| Remembering that energy must be conserved, what do you think becomes of the energy extracted from food during cellular respiration? | Some of it is stored in ATP molecules; the rest is released as heat |
| ATP |
Adenosine triphosphate, the main energy source for cells
Image:
Atp+2 (binary/octet-stream)
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| Phosphorylation | The transfer of a phosphate group, usually from ATP, to a molecule. |
| Explain how ATP transfers energy from exergonic to endergonic processes in the cell. | Exergonic processes phosphorylate ADP to form ATP. ATP transfers energy to endergonic processes, often by phosphorylating other molecules. |
| Activation energy | The amount of energy that reactants must absorb before a chemical reaction will start |
| Enzymes | Molecules that function as biological catalysts, increasing the rate of a reaction without being consumed by the reaction |
| The effect of an enzyme in lowering the activation energy | |
| Substrate | The specific reactant that an enzyme acts on |
| Active Site | The part of an enzyme where the substrate molecule attaches; typically, a pocket or groove on the enzyme's surface |
| The catalytic cycle of an enzyme | |
| Induced Fit | The change in shape of the active site of an enzyme, caused by entry of the substrate so that it binds the substrate snugly |
| Cofactor | A non-protein molecule or ion that binds to the active site and function in catalysis |
| Coenzyme | An organic molecule serving as a cofactor. Most vitamins function as coenzymes in important metabolic reactions |
| Explain how an enzyme speeds up a specific reaction. | An enzyme lowers the activation energy needed for a reaction when its specific substrate enters its active site. With an induced fit, the enzyme strains bonds that need to break or positions substrates in an orientation that aids the conversion of reactants to products. |
| Inhibitor | A chemical that interferes with an enzyme's activity |
| Competitive Inhibitor | Reduces an enzyme’s productivity by blocking substrate molecules from entering the active site |
| How inhibitors interfere with substrate binding |
Image:
How (binary/octet-stream)
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| Noncompetitive Inhibitor | Changes the enzyme's productivity by blocking substrate molecules from entering the active site |
| Feedback Inhibition | A method of metabolic control in which a product of metabolic pathway acts as an inhibitor of an enzyme within that pathway |
| Explain an advantage of feedback inhibition to a cell. | It prevents the cell from wasting valuable resources by synthesizing more of a particular product than is needed. |
| What determines whether enzyme inhibition is reversible or irreversible? | If the inhibitor binds to the enzyme with covalent bonds, the inhibition is usually irreversible. When weak chemical interactions bind inhibitor and enzyme, the inhibition is reversible. |
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