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General Biology Exam 2 Study Guide

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Termini in questo insieme (42)

  • What is the plasma membrane and its major functions?
    Separates and controls traffic into and out of cells; found outside of cells in all cell types.
  • What is the fluid mosaic model?
    Membrane is a fluid structure with proteins embedded or attached to a double layer of phospholipids.
  • How do temperature and cholesterol influence membrane fluidity?
    Higher temperature increases fluidity; cholesterol fills holes to stabilize membrane fluidity.
  • What are peripheral and integral membrane proteins?
    Peripheral proteins are loosely bound to membrane surface; integral proteins penetrate the hydrophobic core.
  • What is meant by a selectively permeable membrane?
    Membrane that allows some molecules to cross more easily than others.
  • Which molecules cross the plasma membrane easily and which do not?
    Small, hydrophobic, uncharged molecules cross easily; large, ionic, or polar molecules require transport proteins.
  • Difference between passive and active transport?
    Passive transport requires no energy and moves molecules down their concentration gradient; active transport requires energy to move molecules against the gradient.
  • What is osmosis?
    Diffusion of water across a selectively permeable membrane.
  • Define hypertonic, hypotonic, and isotonic solutions.
    Hypertonic: higher solute concentration; Hypotonic: lower solute concentration; Isotonic: equal solute concentration.
  • Effect of tonicity on animal and plant cells?
    Animal cells: hypo causes lysis, iso normal, hyper shriveled. Plant cells: hypo turgid, iso flaccid, hyper plasmolyzed.
  • What is facilitated diffusion?
    Passive movement of molecules down their concentration gradient via transport proteins.
  • What are aquaporins?
    Gated channel proteins that facilitate water transport across membranes.
  • What is active transport? Give an example.
    Energy-requiring transport moving molecules against their gradient; example: sodium-potassium pump.
  • Difference between endocytosis and exocytosis?
    Endocytosis brings materials into the cell; exocytosis releases substances from the cell.
  • What is a signal transduction pathway?
    Process converting a signal on a cell’s surface into a specific cellular response.
  • Define paracrine, synaptic, endocrine, and direct contact signaling.
    Paracrine: local signaling; Synaptic: nerve cell neurotransmitters; Endocrine: hormones over long distances; Direct contact: cell-to-cell communication.
  • What are the three stages of cell signaling?
    Reception: ligand binds receptor; Transduction: signal relayed and amplified; Response: specific cellular activity triggered.
  • What is a ligand?
    A molecule that binds specifically to a receptor to initiate signaling.
  • What is metabolism?
    Collection of all chemical reactions in an organism.
  • Difference between catabolic and anabolic pathways?
    Catabolic pathways release energy by breaking down molecules; anabolic pathways consume energy to build molecules.
  • What are the first and second laws of thermodynamics?
    First: energy cannot be created or destroyed; Second: energy transformations increase entropy (disorder).
  • What is free energy (G)?
    Energy in a system available to do work.
  • Difference between exergonic and endergonic reactions?
    Exergonic reactions release free energy (ΔG negative); endergonic reactions absorb free energy (ΔG positive).
  • What is ATP and how is it used by cells?
    Adenosine triphosphate; main energy currency; energy released by hydrolysis powers cellular work.
  • What is an enzyme and how does it function?
    A catalytic protein that lowers activation energy to speed up reactions without changing ΔG.
  • What is activation energy?
    Energy required to start a chemical reaction by overcoming the energy barrier.
  • What are cofactors and why are vitamins and minerals important?
    Nonprotein helpers for enzymes; vitamins and minerals often serve as cofactors.
  • Compare competitive and noncompetitive enzyme inhibitors.
    Competitive inhibitors block substrate binding at active site; noncompetitive inhibitors bind elsewhere altering enzyme function.
  • What is feedback inhibition?
    End product of a metabolic pathway inhibits an earlier step to prevent overproduction.
  • What is cellular respiration?
    Process of harvesting chemical energy by breaking down sugars, mainly in mitochondria.
  • What are oxidation and reduction in redox reactions?
    Oxidation: loss of electrons; reduction: gain of electrons.
  • What is glycolysis and where does it occur?
    Breakdown of glucose into pyruvate; occurs in cytoplasm.
  • What is the role of the electron transport chain?
    Transfers electrons to oxygen through proteins in inner mitochondrial membrane, creating a proton gradient for ATP synthesis.
  • What is chemiosmosis?
    ATP synthesis powered by proton gradient across membrane.
  • What is fermentation and why does it occur?
    Anaerobic ATP production when oxygen is absent; partial sugar breakdown.
  • What is an autotroph and a heterotroph?
    Autotrophs produce organic molecules from CO2; heterotrophs consume organic compounds from others.
  • What is the primary function of chloroplasts?
    Site of photosynthesis; contains chlorophyll; found in mesophyll cells.
  • What is the basic chemical equation for photosynthesis?
    6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
  • Where do light reactions occur and what do they produce?
    Occur in thylakoid membranes; produce ATP, NADPH, and oxygen.
  • What is the Calvin cycle and where does it occur?
    Carbon fixation cycle in stroma; uses ATP and NADPH to produce sugar from CO2.
  • What is photorespiration and why is it harmful?
    Oxygen competes with CO2 in Calvin cycle, reducing photosynthetic efficiency.
  • How do C4 and CAM plants minimize photorespiration?
    By spatial (C4) or temporal (CAM) separation of carbon fixation and Calvin cycle.