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General Biology: Cell Structure, Membranes, Metabolism, and Respiration

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  • What is the function of the nucleus in a cell?
    The nucleus contains genetic material (DNA) and controls cell activities.
  • What is the role of mitochondria?
    Mitochondria are the site of cellular respiration and produce ATP.
  • Where does photosynthesis occur in plant cells?
    Photosynthesis occurs in chloroplasts found in plant cells.
  • What are the main functions of the rough and smooth endoplasmic reticulum?
    Rough ER synthesizes proteins, while Smooth ER synthesizes lipids.
  • What is the function of the Golgi apparatus?
    The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport.
  • What do lysosomes do in a cell?
    Lysosomes contain digestive enzymes that break down waste materials.
  • How do ribosomes contribute to the cell?
    Ribosomes synthesize proteins and can be free in cytoplasm or attached to the ER.
  • What distinguishes prokaryotic cells from eukaryotic cells?
    Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.
  • Name three structures common to all cells.
    All cells have a plasma membrane, cytoplasm, and ribosomes.
  • What unique structures are found in plant cells but not animal cells?
    Plant cells have a cell wall, chloroplasts, and a large central vacuole.
  • What is the fluid mosaic model of the plasma membrane?
    It describes the membrane as a dynamic phospholipid bilayer with embedded proteins and cholesterol.
  • What roles do membrane proteins play?
    Membrane proteins function in transport, signal reception, and cell recognition.
  • Which molecules can easily cross the lipid bilayer without assistance?
    Hydrophobic molecules like O2, CO2, and steroid hormones cross easily.
  • Define diffusion and osmosis.
    Diffusion is the passive movement of molecules from high to low concentration; osmosis is diffusion of water across a membrane.
  • What happens to a cell in isotonic, hypertonic, and hypotonic solutions?
    Isotonic: no net water movement; Hypertonic: cell loses water; Hypotonic: cell gains water.
  • What is metabolism?
    Metabolism is the sum of all chemical reactions in a cell, including catabolic and anabolic pathways.
  • What is anabolism?
    Anabolism builds complex molecules from simpler ones and requires energy input.
  • State the first and second laws of thermodynamics in biological systems.
    First law: energy cannot be created or destroyed, only transformed. Second law: energy transfers increase entropy.
  • What is chemical equilibrium?
    Chemical equilibrium occurs when forward and reverse reaction rates are equal, with no net change in concentrations.
  • How does ATP function in cellular work?
    ATP hydrolysis releases energy used for mechanical, transport, and chemical work in cells.
  • What are enzymes and how do cofactors and inhibitors affect them?
    Enzymes speed reactions by lowering activation energy; cofactors assist enzymes; inhibitors reduce enzyme activity.
  • What are oxidation and reduction in cellular respiration?
    Oxidation is loss of electrons; reduction is gain of electrons during redox reactions.
  • What roles do NAD+, NADH, FAD, and FADH2 play?
    NAD+ and FAD accept electrons becoming NADH and FADH2, which carry electrons in metabolism.
  • List the stages of cellular respiration and their locations.
    Glycolysis (cytoplasm), Pyruvate oxidation (mitochondrial matrix), Citric Acid Cycle (mitochondrial matrix), Electron Transport Chain (inner mitochondrial membrane).
  • How many ATP molecules are produced per glucose in cellular respiration?
    About 30-32 ATP per glucose: 2 from glycolysis, 2 from citric acid cycle, and ~26-28 from electron transport chain.
  • What happens during lactic acid fermentation?
    Pyruvate is reduced to lactic acid when oxygen is unavailable, such as in muscle cells.
  • Describe alcohol fermentation.
    Pyruvate is converted to ethanol and CO2, occurring in yeast under anaerobic conditions.
  • What is anaerobic respiration and give examples of electron acceptors?
    Anaerobic respiration uses electron acceptors other than O2, like nitrate (NO3-), sulfate (SO42-), producing products like nitrite, hydrogen sulfide, or methane.