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Terms in this set (20)

  • What is the plasma membrane and its main functions?
    The plasma membrane is a selectively permeable barrier separating the inside of the cell from extracellular fluid. It controls entry of ions and nutrients, elimination of wastes, and release of secretions.
  • What are the main components of the plasma membrane?
    The plasma membrane is composed of a phospholipid bilayer, proteins, and a glycocalyx formed by superficial membrane carbohydrates.
  • Describe the structure of the phospholipid bilayer.
    It consists of two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward. Cholesterol molecules are interspersed to stiffen the membrane.
  • What are integral and peripheral proteins in the plasma membrane?
    Integral proteins span the membrane and can transport water or solutes. Peripheral proteins attach to the membrane surface and often have regulatory or enzymatic functions.
  • What is the glycocalyx and its functions?
    The glycocalyx is a layer of membrane carbohydrates including proteoglycans, glycoproteins, and glycolipids. It functions in cell recognition, binding to extracellular structures, and lubrication of the cell surface.
  • List the functional classes of membrane proteins.
    Anchoring proteins stabilize membrane position, recognition proteins are detected by immune cells, enzymes catalyze reactions, receptor proteins bind ligands, carrier proteins transport solutes, and channels allow passage of water and small solutes.
  • What is the cytoskeleton and its main components?
    The cytoskeleton is a network of protein filaments including microfilaments (actin), intermediate filaments, thick filaments (myosin), and microtubules. It provides strength, shape, and organelle movement.
  • Describe the structure and function of mitochondria.
    Mitochondria have a double membrane with inner folds called cristae enclosing the matrix. They produce ATP and contain their own DNA and ribosomes.
  • What is the nuclear envelope and its role?
    The nuclear envelope is a double membrane separating the nucleus from the cytoplasm. It contains nuclear pores that regulate movement of ions and molecules.
  • How is DNA organized inside the nucleus?
    DNA strands coil around histone proteins forming nucleosomes. Loosely coiled DNA is called chromatin in nondividing cells, and tightly coiled DNA forms chromosomes during cell division.
  • Define permeability in the context of cell membranes.
    Permeability is the property determining which substances can enter or leave the cytoplasm. Membranes can be freely permeable, selectively permeable, or impermeable.
  • What factors influence selective permeability of membranes?
    Factors include size, molecular shape, lipid solubility, electrical charge of materials, and the types and arrangement of lipids and proteins in the membrane.
  • Differentiate between passive and active membrane transport processes.
    Passive transport does not require ATP and includes diffusion and carrier-mediated transport. Active transport requires ATP and includes vesicular transport and active carrier-mediated transport.
  • What is diffusion and what factors affect its rate?
    Diffusion is the net movement of substances from higher to lower concentration. Rate is influenced by distance, molecule size, temperature, concentration gradient, and electrical forces.
  • Explain osmosis and osmotic pressure.
    Osmosis is the net diffusion of water across a selectively permeable membrane. Osmotic pressure is the force of water moving into a solution with higher solute concentration.
  • What are isotonic, hypotonic, and hypertonic solutions?
    Isotonic solutions cause no net water movement. Hypotonic solutions cause water to enter cells, possibly causing swelling. Hypertonic solutions cause water to leave cells, causing shrinkage.
  • Describe carrier-mediated transport and its types.
    Carrier proteins transport hydrophilic or large molecules. Types include facilitated diffusion (passive), active transport (requires ATP), and secondary active transport (uses concentration gradients).
  • What is receptor-mediated endocytosis?
    A process where specific molecules bind to receptors on the membrane, triggering vesicle formation to import substances into the cell.
  • What is the difference between pinocytosis and phagocytosis?
    Pinocytosis is the nonspecific uptake of extracellular fluid and small molecules. Phagocytosis is the engulfing of large particles or cells by specialized cells like macrophages.
  • What is exocytosis?
    Exocytosis is the process of vesicles fusing with the plasma membrane to release wastes or secretory products outside the cell.