BIO 100 EXAM 2 LATEST VERSION GRADED A+

BIO 100 EXAM 2 LATEST VERSION GRADED A+ LECTURE#6 Cell Communication **What is the role of the plasma membrane in a cell?** The plasma membrane acts as the "gatekeeper" of the cell, separating it from its environment and regulating the passage of molecules. It is composed of a hydrophobic phospholipid bilayer that allows small and hydrophobic molecules to pass through. **What are concentration gradients in cellular context?** Concentration gradients refer to the differences in the concentration of substances across a membrane, from areas of abundance to areas of scarcity. **Describe passive transport across membranes.** Passive transport involves the movement of molecules from areas of high concentration to areas of low concentration without the input of energy. Small molecules diffuse freely, while larger molecules and ions use protein carriers like channel proteins or carrier proteins. **Explain active transport and give an example.** Active transport moves molecules against their concentration gradient, from areas of low to high concentration, requiring energy usually from ATP. An example is the sodium-potassium pump, crucial for maintaining cellular functions. **What is osmosis?** Osmosis is the passive movement of water across a membrane, responding to concentration gradients of solutes. **Differentiate between exocytosis and endocytosis.** Exocytosis involves the release of substances from the cell through fusion of transport vesicles with the plasma membrane. Endocytosis is the process where the cell membrane forms vesicles to bring substances into the cell, including pinocytosis (non-specific) and receptor-mediated (specific) endocytosis. **Define phagocytosis and provide an example.** Phagocytosis is the ingestion of whole cells or large particles by the cell. An example is amoebas consuming prey like paramecium by extending pseudopodia around them. **Where can receptors for cell signaling be located?** Receptors can exist on the outside of the cell, on its surface, inside the cell, on other surfaces, within signaling cascades, inside the nucleus, and as gene activation points. LECTURE#7 Energy and Enzymes **What is metabolism?** Metabolism encompasses all chemical reactions in the body that transfer energy, governed by the laws of thermodynamics, particularly the conservation of energy and the increase in disorder (entropy). **What defines disorder in a cell?** Disorder in a cell is characterized by random arrangement of molecules. **Differentiate between anabolism and catabolism.** Anabolism involves the synthesis of polymers from monomers through biosynthetic reactions, requiring ATP. Catabolism, on the other hand, breaks down complex molecules into simpler ones, releasing energy. This restructuring clarifies and simplifies the questions while maintaining the essential information about cell communication and energy metabolism. Turns polymers into monomers. The breakdown reactions of complex molecules to release energy. Creates ATP. ATP Energy-storing molecules in all cells. Universal energy carrier. 6 main ideas of the Carbon Cycle 1. all living organisms require energy to survive 2. Sun is the source of most energy on Earth 3. Light energy is used by producers to synthesize sugars 4. Plants and cyanobactreia perform photosynthesis 5. For non-photosynthesizing organisms (mostly consumers), energy is acquired from food molecules. 6. Carbon dioxide and food molecules are involved in this energy transfer. Using Energy from food Energy transfer in non-living organisms can be explosive (combustion). Energy transfer in cells is controlled. Carbon in wood + O2... --- CO2 + H2O + energy Carbon in food + O2...