Transport across cell membranes

• What are the two types of transport mentioned for cell membranes?

  Diffusion and Active transport
• What does Fick's first law describe?

  It describes the rate of diffusion based on surface area and length of diffusion path
• What is the role of ATP in cellular transport?

  ATP provides energy for conformational changes in proteins
• What is the equation for ATP breakdown?

  ATP → ADP + Pi + energy
• What is the function of the Sodium-Potassium pump?

  It pumps 2 K+ ions into the cell and 3 Na+ ions out of the cell
• How does the Na+/K+ pump contribute to the cell's potential?

  It maintains a concentration gradient that contributes to the cell's membrane potential
• What is the difference between hypotonic and hypertonic solutions?

  Hypotonic solutions have lower solute concentration, while hypertonic solutions have higher solute concentration
• What is the driving force for diffusion across lipid bilayers?

  The concentration gradient
• What is facilitated diffusion?

  It is the process of transporting substances across a membrane with the help of carrier proteins
• How does passive transport differ from active transport?

  Passive transport does not require energy, while active transport does
• What are the steps involved in the active transport of a single particle?

  • Phosphorylation occurs during one part of the concentration gradient
  • ATP is used to create co-transport of a particle
  • Requires 3 particles for transport
  • Generates movement against the concentration gradient
• What are the key components of the Sodium-Potassium pump's function?

  • Pumps 3 Na+ ions out of the cell
  • Pumps 2 K+ ions into the cell
  • Maintains the cell's membrane potential
  • Uses ATP for energy
• What is the process of passive cotransport of two particles?

  • Involves up to 2 K+ ions with Na+ ions
  • Requires a 1:1 binding site for passive transport
  • Driven by the force of the gradient
  • Symport mechanism brings particles across the membrane
• What is the significance of the electrogenic gradient?

  • Establishes a charge difference across the membrane
  • Influences the movement of ions
  • Contributes to the overall membrane potential
• What is the role of water in osmosis?

  • Water moves from areas of high water potential to low water potential
  • Influences cell volume and pressure
  • Essential for maintaining cellular homeostasis
• What is the relationship between concentration gradients and diffusion?

  • Diffusion occurs from areas of high concentration to low concentration
  • Concentration gradients drive the movement of particles
  • Essential for nutrient uptake and waste removal in cells
• What is the significance of ATP in cellular processes?

  • ATP serves as the primary energy currency of the cell
  • Powers various cellular functions, including transport
  • Synthesized through condensation reactions
• What is the role of carrier proteins in facilitated diffusion?

  • Carrier proteins bind to specific molecules
  • Assist in transporting substances across the membrane
  • Enable movement along the concentration gradient
• How does the concentration of glucose affect its diffusion across cell membranes?

  • Glucose diffusion is driven by concentration differences
  • Facilitated diffusion occurs through specific transport proteins
  • Higher concentrations lead to increased flux across membranes
• What forms the boundary between the cell cytoplasm and the environment?

  The cell membrane
• What are the two main components of a phospholipid?

  Hydrophilic head and hydrophobic tail
• How does the hydrophilic head of phospholipids interact with water?

  It points towards water and is attracted by it
• What is the orientation of the hydrophobic tail of phospholipids in relation to water?

  It points away from water and repels it
• What structure do phospholipids form in the cell membrane?

  A bilayer
• What role do proteins play in the cell membrane?

  They help hold lipids together and allow selective transport
• What is the function of cholesterol in the cell membrane?

  It makes the membrane fluid at high temperatures and reduces permeability
• How is cholesterol characterized in terms of its polarity?

  It is hydrophilic on one side and hydrophobic on the other
• What is the function of glycolipids in the cell membrane?

  They act as cell-surface receptors and maintain stability
• What role do glycoproteins play in the cell membrane?

  They aid in specificity for hormones and neurotransmitters
• What is diffusion?

  The movement of molecules from high concentration to low concentration
• Which types of molecules can readily diffuse across membranes?

  O₂, CO₂, C₂H₂, and polar molecules like Na⁺ and Cl⁻
• Why do uncharged non-polar molecules not easily diffuse across cell membranes?

  Due to the hydrophobic nature of cell walls
• What is facilitated diffusion?

  The process that makes movement easier through transmembrane channels
• Is facilitated diffusion active or passive transport?

  Passive transport
• What is osmosis?

  The passage of water from a region of high water potential to low water potential
• What happens to a plant cell in pure water?

  Water enters, causing the cytoplasm to swell
• What occurs when the water potential is lower outside a plant cell?

  Water leaves, causing the cytoplasm to shrink
• What is turgor pressure?

  The pressure exerted by the fluid inside the cell against the cell wall
• What is plasmolysis?

  The process where the cytoplasm shrinks away from the cell wall
• What is passive transport?

  The movement of molecules from high concentration to low concentration without ATP