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BIO Chpt. 5 Test
Biology test on Chapter 5
| Question | Answer |
|---|---|
| What is the function of the steroid, cholesterol, in a membrane? | It helps stabilize the membrane at warm temperatures but also helps keep the membrane fluid at lower temperatures. |
| What is the function of integrins in a membrane? | They attach to the cytoskeleton on the inside and the extracellular matrix on the outside (structure). |
| What is the function of glycoproteins/glycolipids in a membrane? | They are involved in cell/cell recognition - carbohydrates are attached to the proteins or lipids and act as ID tags that are recognized by other cells. |
| What does cell-cell recognition in cells enable cells to do? | 1) Sort themselves into tissues and organs 2) Recognize and reject foreign cells (bacteria) |
| What are the 5 functions of plasma membrane proteins? | 1) Stronger framework 2) Cell-cell recognition 3) Forming junctions between cells 4) Enzymes 5) Receptors |
| What is a receptor (how does it work)? | It is a protein that has a shape that fits a specific messenger, such as a hormone. The binding of the messenger to the receptor triggers a chain reaction involving other proteins which relay the message to molecules that perform specific functions inside |
| Define: Selective permeability | Membranes that allow some substances to cross more easily than others. |
| Which molecules can easily pass through membranes? Which molecules cannot pass through membranes? | Nonpolar, hydrophobic and/or small molcules can easily pass through. Polar molecules, big molecules and ions are not soluble in lipids. |
| Define: Diffusion | The tendency for particles of any kind to spread out evenly in an available space, from where they are more concentrated to where they are less concentrated (moving down their concentration gradient). |
| What is passive transport? | Diffusion of a substance across a biological membrane (the cell is not performing work). |
| Define: Tonicity | The ability of a solution to cause a cell to gain or lose water. |
| Define: 1) Isotonic 2) Hypotonic 3) Hypertonic | 1) Isotonic: solute concentration of cell and environment are equal 2) Hypotonic: a solution with a solute concentration lower than that of the cell 3) Hypertonic: a solution with a higher solute concentration than that of the cell |
| What is the control of water balance called? | Osmoregulation |
| A plant cell thrives best in what kind of environment? An animal cell? | Plant cell: Hypotonic solution Animal cell: Isotonic solution |
| Describe: Facilitated diffusion | The diffusion of a substance that cannot diffuse freely across membrane (because of polarity or charge) with help from transport proteins. |
| What are aquaporins? | Transport proteins that assist the very rapid diffusion of water into and out of certain cells. |
| Describe: Active transport | When a cell must expend energy to move a solute against its concentration gradient. |
| Describe: Enzymes | They are used in all metabolic reactions to control the rate of reactions and decrease the amount of energy necessary for the reaction to take place. They are specific for each reaction and are reusable. |
| Describe the process of active transport. | 1) The solute attaches to the binding site on the transport protein. 2) ATP transfers one of its phosphate groups to the transport protein. 3) The protein changes shape in such a way that the solute is released on the other side. |
| Give an example of active transport in the human body. | The inside of an animal cell has a higher concentration of potassium ions and a lower concentration of sodium ions than the solution outside the cell. The generation of nerve signals depends on these concentration differences. |
| Describe Exocytosis. | When a cell EXPORTS bulky materials such a proteins or polysaccharides. |
| Describe Endocytosis. | When a cell IMPORTS substances (takes in substances). |
| Name and describe the 3 kinds of endocytosis. | Phagocytosis: "cellular eating" - cell engulfs the particle by wrapping extensions. Pinocytosis: "cellular drinking" - cell gulps droplets of fluid into vesicles. Receptor-mediated endocytosis: receptor proteins receive molecules and pinch in. |
| Define: Energy | The capacity to perform work/ the capacity to rearrange matter. |
| Define: Kinetic energy Name a form of kinetic energy. | The energy of motion. Heat (thermal energy) is a form of kinetic energy associated with the random movement of atoms or molecules. |
| Define: Potential energy Name a form of potential energy. | Stored energy that an object possesses as a result of its location or structure. Chemical energy is a form of potential energy available for release in a chemical reaction (most important type of energy for living organisms). |
| Define: Thermodynamics Name the 2 laws. | The study of energy transformations that occur in a collection of matter. 1) Law of energy conservation - energy in the universe is constant (cannot be created or destroyed 2)Energy conversions increase the entropy (disorder) of the universe |
| Define: Exergonic reaction | A chemical reaction that releases energy. (e.g. cellular respiration) |
| Define: Endergonic reaction | A chemical reaction that yields products that are rich in potential energy (e.g. photosynthesis) |
| Describe: Cellular respiration | A chemical process that uses oxygen to convert the chemical energy stored in fuel molecules to a form of chemical energy that the cell can use to perform work. |
| What is metabolism? | The total of an organism's chemical reactions. |
| What is a metabolic pathway? | A series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds. |
| Describe energy coupling. | The use of energy released from exergonic reactions to drive essential endergonic reactions. |
| What is ATP and what is it made of? | Adenosine triphosphate - adenine, ribose, and 3 phosphate groups. |
| How is ATP converted to ADP? | Hydrolysis |
| How do enzymes speed up the cell's chemical reactions? | By lowering energy barriers. |
| Define: Energy of Activation (EA) | The amount of energy needed to push the reactants over the energy barrier. |
| Define: Substrate | A specific reactant that an enzyme acts on. |
| Define: Active site | A region of the enzyme that the substrate fits into. |
| Describe the catalytic cyle of an enzyme. | 1) Sucrose enters sucrase's active site by weak bonds (the active site changes shape slightly - induced fit) 2) Strained bond reacts with water and the substrate in converted to the products |
| What are the optimal conditions for enzymes? | 35-40 degrees celcius. pH of 6-8. |
| What are cofactors? | Nonprotein helpers that are organic molecules. |
| What is an inhibitor? | A chemical that interferes with an enzyme's activity. |
| What is a competitive inhibitor? | An inhibitor that reduces an enzyme's productivity by blocking substrates from entering the active site. |
| What is a noncompetitive inhibitor? | An inhibitor that does not enter the active site - instead it binds to the enzyme somewhere else, changing the enzyme's shape in the process. |
| Describe: Feedback inhibition | If a cell is producing more of that product than it needs, the product acts as an inhibitor of one of the enzymes. |
Created by:
Tarayellow
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