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Bio Exam 3
| Question | Answer |
|---|---|
| What is light microscopy? | A technique that uses visible light and a system of lenses to magnify images of small samples. |
| What are the main parts of a light microscope? | eyepiece, objective lenses, stage, light source, and base. |
| How can contrast be increased in microscopy? | Contrast can be increased using stains, adjusting light intensity, or using phase contrast techniques. |
| What is the difference between SEM and TEM? | SEM (Scanning Electron Microscope) provides 3D images of surfaces, while TEM (Transmission Electron Microscope) provides detailed images of internal structures. |
| What are the major differences between prokaryotic and eukaryotic cells? | Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and organelles. |
| What are the major functions of the endomembrane system? | Functions include protein synthesis, modification, transport, and lipid synthesis. |
| What structures are part of the endomembrane system? | Structures include the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and vesicles. |
| What is the function of rough and smooth ER? | Rough ER synthesizes proteins, while smooth ER is involved in lipid synthesis and detoxification. |
| What are lysosomes and their function? | Lysosomes are organelles that contain digestive enzymes to break down waste materials and cellular debris. |
| What are phagocytosis and autophagy? | Phagocytosis is the process of engulfing large particles, while autophagy is the degradation of damaged organelles. |
| What is the structure and function of mitochondria? | Mitochondria have a double membrane and are responsible for ATP production through cellular respiration. |
| What is the structure and function of chloroplasts? | Chloroplasts have a double membrane and contain chlorophyll for photosynthesis. |
| What are peroxisomes and their function? | Peroxisomes are organelles that contain enzymes for breaking down fatty acids and detoxifying harmful substances. |
| What are the generalized functions of the cytoskeleton? | Functions include maintaining cell shape, enabling cell movement, and facilitating intracellular transport. |
| What are the three main types of cytoskeletal elements? | Microfilaments (actin), intermediate filaments (various proteins), and microtubules (tubulin). |
| What are the major extracellular structures and their functions? | Major structures include the extracellular matrix (support and adhesion) and cell walls (protection and structure). |
| What are the different types of intracellular junctions in plants and animals? | Types include tight junctions, gap junctions, and desmosomes in animals; plasmodesmata in plants. |
| Why is the plasma membrane considered selectively permeable? | It allows certain substances to pass while restricting others based on size, charge, and solubility. |
| What are the major components of the plasma membrane? | Components include phospholipids, proteins, cholesterol, and carbohydrates. |
| What is the structure of phospholipids? | Phospholipids have a hydrophilic head and two hydrophobic tails, making them amphipathic. |
| What does the fluid mosaic model of membrane structure mean? | It describes the membrane as a fluid combination of lipids and proteins that can move laterally. |
| How do temperature and hydrocarbon tail type affect membrane fluidity? | higher temperatures increase fluidity, while unsaturated tails increase fluidity by creating kinks that prevent tight packing, whereas saturated tails decrease fluidity because they can pack tightly. |
| What role does cholesterol play in the plasma membrane? | Cholesterol stabilizes membrane fluidity across temperature changes. |
| What is an integral membrane protein? | A protein that spans the membrane and is involved in transport or signaling. |
| What is a peripheral protein? | A protein located on the membrane's surface, often involved in signaling or structural support. |
| What are the major functions of membrane proteins? | Functions include transport, enzyme activity, signal transduction, and cell-cell recognition. |
| How do membrane carbohydrates contribute to cell-cell recognition? | They serve as identification tags that are recognized by other cells. |
| Why do polar/charged/hydrophilic substances not cross the membrane effectively? | They cannot easily pass through the hydrophobic lipid bilayer. |
| What is diffusion? | The movement of molecules from an area of higher concentration to an area of lower concentration. |
| What is passive transport? | The movement of substances across a membrane without the use of energy, down their concentration gradient. |
| What is osmosis? | The diffusion of water across a selectively permeable membrane. |
| What do the terms hypertonic, hypotonic, and isotonic mean? | Hypertonic has a higher solute concentration, hypotonic has a lower concentration, and isotonic has equal concentrations. |
| What are the states turgid, flaccid, and plasmolyzed? | Turgid is swollen, flaccid is limp, and plasmolyzed is shriveled, based on water movement. |
| How do animal and plant cells control water balance? | Animal cells use osmoregulation; plant cells use turgor pressure. |
| What is facilitated diffusion? | A type of passive transport that requires channel or carrier proteins but no energy. |
| What are examples of channel proteins? | aquaporins (for water), voltage-gated sodium and potassium channels (for ion movement), and ligand-gated channels that open upon binding to a specific molecule like a neurotransmitter |
| How do carrier proteins work? | They bind to specific molecules and change shape to transport them across the membrane. |
| What is active transport? | The movement of substances against their concentration gradient, requiring energy. |
| What are ion pumps? | Transport proteins that move ions across membranes, often against their concentration gradient. |
| How does the sodium/potassium pump work? | It transports sodium out of the cell and potassium into the cell, using ATP. |
| What is membrane potential? | The voltage difference across a membrane due to the distribution of ions. |
| What is coupled transport? | A process where the transport of one substance is linked to the transport of another. |
| What is secondary active transport? | Transport that uses the energy from the electrochemical gradient created by primary active transport. |
| What are endocytosis and exocytosis? | Endocytosis is the process of taking substances into the cell, while exocytosis is the process of expelling substances. |
| What are the types of endocytosis? | Types include phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis. |
| What does the first law of thermodynamics state? | Energy can be transferred and transformed, but cannot be created or destroyed. |
| What is metabolism? | The sum of all chemical reactions in an organism, including catabolic and anabolic reactions. |
| What is free energy (G)? | amount of energy available to do work |
| What does the formula ∆G = Gproducts - Greactants represent? | It calculates the change in free energy during a reaction. |
| What are exergonic reactions? | Reactions with a negative ∆G that are spontaneous and release energy. |
| What are endergonic reactions? | Reactions with a positive ∆G that require energy and are not spontaneous. |
| What are enzymes? | Proteins that catalyze chemical reactions by lowering the activation energy (EA). |
| What is an activation barrier? | The energy threshold that must be overcome for a reaction to proceed. |
| How do enzymes lower the activation energy? | By stabilizing the transition state and providing an optimal environment for the reaction. |
| What is an active site? | The specific region of an enzyme where substrates bind and reactions occur. |
| What factors affect enzyme activity? | Factors include temperature, pH, cofactors, and coenzymes. |
| What is competitive inhibition? | When an inhibitor competes with the substrate for the active site of an enzyme. |
| What is noncompetitive inhibition? | When an inhibitor binds to an enzyme away from the active site, altering its function. |
| What is allosteric regulation? | Regulation of enzyme activity through binding at sites other than the active site. |
| Where are enzymes localized? | Enzymes are localized in specific areas such as mitochondria or membranes based on their function. |
| What is ATP and its role in cellular reactions? | ATP is the energy currency of the cell, and its hydrolysis is coupled to endergonic reactions. |
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