chapter 4

• What is the main focus of the study material?

  Transport across cell membranes
• What is the fluid mosaic model related to?

  Structure of the cell membrane
• What do phospholipids contribute to in the cell membrane?

  They form the bilayer structure
• What role does cholesterol play in the cell membrane?

  It stabilizes the membrane structure
• What are glycolipids and glycoproteins used for in the cell membrane?

  They are involved in cell recognition
• What is the function of the plasma membrane?

  It controls entry and exit of substances
• How do organelles like mitochondria differ in membrane structure?

  They are surrounded by two membranes
• What is diffusion?

  Movement of particles from high to low concentration
• What affects the rate of diffusion?

  Concentration gradient and temperature
• What is the difference between simple and facilitated diffusion?

  Facilitated diffusion requires protein channels
• What is the role of the endoplasmic reticulum?

  It provides an internal transport system
• What does the fluid mosaic model describe?

  The arrangement of molecules in the membrane
• What is meant by a selectively permeable membrane?

  It allows certain substances to pass through
• What is the water potential of pure water under standard conditions?

  0 kPa
• How do cells with different water potentials interact?

  Water moves from higher to lower potential
• What is active transport?

  Movement of substances against a concentration gradient
• What is co-transport in the context of glucose absorption?

  Transport of glucose with sodium ions
• How do microvilli assist in absorption?

  They increase surface area for absorption
• What is the difference between villi and microvilli?

  Villi are larger projections than microvilli
• What happens to glucose concentration in the ileum during digestion?

  It increases due to digestion of carbohydrates
• How does the heart contribute to maintaining concentration gradients?

  It circulates blood continuously
• What is the role of facilitated diffusion in nutrient absorption?

  It allows glucose to enter the blood
• What is the significance of the concentration gradient in absorption?

  It drives the movement of nutrients
• What is the role of carrier proteins in facilitated diffusion?

  They help transport specific molecules across membranes
• How does the hydrophobic nature of fatty acid tails affect diffusion?

  It prevents polar molecules from passing
• What is the importance of kinetic energy in diffusion?

  It causes particles to move randomly
• How does facilitated diffusion differ from simple diffusion?

  Facilitated diffusion requires specific proteins
• What is the significance of the brush border in the ileum?

  It increases the surface area for absorption
• What happens to glucose when the concentration in the ileum equals that in the blood?

  Facilitated diffusion stops as equilibrium is reached
• What is the role of sodium ions in glucose absorption?

  They assist in co-transport with glucose
• How does the structure of microvilli enhance absorption?

  They provide a larger area for nutrient uptake
• What is the function of the epithelial cells in the ileum?

  They facilitate nutrient absorption
• What is the relationship between diffusion and concentration gradients?

  Diffusion occurs down concentration gradients
• What is the significance of maintaining a concentration gradient in the ileum?

  It ensures efficient nutrient absorption
• How do carrier proteins function in facilitated diffusion?

  They change shape to transport molecules
• What is the role of the heart in nutrient absorption?

  It maintains blood flow to support absorption
• How does the structure of the cell membrane relate to its function?

  The fluid mosaic model allows flexibility and function
• What is the importance of the kinetic energy of particles in diffusion?

  It drives the movement of particles
• What is the role of the cell wall in relation to the cell membrane?

  It provides structural support and protection
• How does the hydrophobic nature of the phospholipid bilayer affect permeability?

  It restricts passage of polar molecules