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General Biology I - Cell Membranes and Energy Study Guide

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  • Structure of cell membranes
    Cell membranes have a fluid mosaic model structure composed mainly of phospholipid bilayers with embedded proteins, allowing selective permeability and diverse functions.
  • Phospholipid molecule structure
    Phospholipids have a hydrophilic head and two hydrophobic tails, enabling spontaneous bilayer formation in aqueous environments.
  • Spontaneous membrane formation
    Phospholipids spontaneously form membranes because hydrophobic tails avoid water while hydrophilic heads interact with water, creating a bilayer.
  • Diffusion
    Diffusion is the passive movement of molecules from an area of higher concentration to lower concentration.
  • Passive transport
    Passive transport moves substances across membranes without energy input, following the concentration gradient.
  • Osmosis
    Osmosis is the diffusion of water across a selectively permeable membrane from low to high solute concentration.
  • Hypertonic solution
    A hypertonic solution has a higher solute concentration than the cell, causing water to leave the cell.
  • Hypotonic solution
    A hypotonic solution has a lower solute concentration than the cell, causing water to enter the cell.
  • Isotonic solution
    An isotonic solution has equal solute concentration to the cell, resulting in no net water movement.
  • Effect of hypertonic solution on animal and plant cells
    Animal cells shrink; plant cells undergo plasmolysis as water leaves the cell.
  • Effect of hypotonic solution on animal and plant cells
    Animal cells may burst; plant cells become turgid due to water intake.
  • Transport proteins in diffusion
    Transport proteins facilitate diffusion by providing specific pathways for molecules to cross membranes.
  • Active transport vs facilitated diffusion
    Active transport requires energy to move substances against their gradient; facilitated diffusion is passive and moves substances down their gradient.
  • Exocytosis
    Exocytosis is the process of vesicles fusing with the plasma membrane to release contents outside the cell.
  • Endocytosis
    Endocytosis is the process of cells engulfing substances by forming vesicles from the plasma membrane.
  • Phagocytosis
    Phagocytosis is a type of endocytosis where large particles or cells are engulfed.
  • Receptor-mediated endocytosis
    A selective form of endocytosis where receptors bind specific molecules before vesicle formation.
  • Kinetic energy
    Kinetic energy is the energy of motion.
  • Potential energy
    Potential energy is stored energy based on position or structure.
  • Chemical energy
    Chemical energy is a form of potential energy stored in chemical bonds.
  • Heat
    Heat is thermal energy transferred between objects due to temperature difference.
  • Endergonic reaction
    An endergonic reaction absorbs energy and is non-spontaneous.
  • Exergonic reaction
    An exergonic reaction releases energy and is spontaneous.
  • Cellular respiration
    Cellular respiration is the process cells use to convert chemical energy from food into ATP.
  • Energy coupling
    Energy coupling uses energy released from exergonic reactions to drive endergonic reactions.
  • ATP function
    ATP functions as an energy shuttle by storing and transferring energy within cells.
  • How enzymes speed up reactions
    Enzymes lower the activation energy required for reactions, speeding up the process.
  • Competitive inhibitor
    A competitive inhibitor binds the enzyme's active site, blocking substrate binding.
  • Noncompetitive inhibitor
    A noncompetitive inhibitor binds elsewhere on the enzyme, changing its shape and reducing activity.