oxidative phosphorylation

• What are the main components of membranes?

  Lipids, proteins, and carbohydrates
• What are phospholipids?

  Amphipathic molecules forming bilayers in water
• How do cholesterol molecules affect membrane fluidity?

  Regulates fluidity by interacting with phospholipids
• What role do glycolipids play in membranes?

  Contribute to cell recognition
• What are integral proteins?

  Proteins embedded within the membrane
• What distinguishes peripheral proteins from integral proteins?

  Peripheral proteins are bound to the membrane surface
• What are amphitropic proteins?

  Proteins that can reversibly attach to membranes
• What role do carbohydrates play in membranes?

  Involved in cell signaling and recognition
• Describe the structure of the phospholipid bilayer.

  Two layers with hydrophobic tails inward, heads outward
• What stabilizes the phospholipid bilayer?

  Hydrophobic interactions in aqueous environments
• What prevents the free passage of polar molecules through the bilayer?

  The non-polar, hydrophobic interior of the bilayer
• Which molecules can diffuse freely through the membrane?

  Small, non-polar molecules like O₂ and CO₂
• What factors influence membrane fluidity?

  Temperature, fatty acid composition, and cholesterol
• How do saturated fatty acids affect membrane fluidity?

  Saturated fatty acids reduce fluidity by packing tightly
• What is the role of cholesterol in membrane fluidity?

  Acts as a buffer to stabilize fluidity
• What can impaired membrane fluidity lead to?

  Reduced oxygen transport in red blood cells
• What is passive transport?

  Movement of molecules down their concentration gradient
• What is osmosis?

  Diffusion of water through a selectively permeable membrane
• What is facilitated diffusion?

  Transport of larger or charged molecules using proteins
• What is active transport?

  Movement against the concentration gradient requiring energy
• What does the Na⁺/K⁺ ATPase pump do?

  Pumps 3 Na⁺ out and 2 K⁺ into the cell
• What is secondary active transport?

  Uses gradients established by primary active transport
• Describe the fluid mosaic model of membranes.

  Dynamic structure with lipids and proteins moving laterally
• What are lipid rafts?

  Membrane regions enriched in cholesterol and sphingolipids
• What are the functions of integral proteins?

  Facilitated diffusion, active transport, and signal transduction
• How did membranes contribute to early life forms?

  Enclosed macromolecules and facilitated biochemical reactions
• What is the primordial soup hypothesis?

  Organic molecules formed from early Earth reactions
• What does the RNA world hypothesis propose?

  RNA was the first self-replicating system
• What is the iron-sulfur world hypothesis?

  High-temperature environments facilitated macromolecule synthesis
• How do phospholipids form bilayers?

  Spontaneously due to hydrophobic interactions
• What did the Gorter and Grendel experiment demonstrate?

  Lipids form bilayers, not monolayers
• What are hydropathy plots used for?

  To predict membrane-spanning regions of proteins
• How does increased cholesterol affect membrane function?

  Decreases fluidity, impairing cell function
• What are the types and functions of membrane proteins?

  Types:

  • Integral proteins: Span the membrane, form channels or carriers
  • Peripheral proteins: Interact with the membrane surface
  • Transmembrane proteins: Often alpha-helical in structure

  
  

  Functions:

  • Facilitated diffusion (e.g., glucose transport)
  • Active transport (e.g., ion pumps)
  • Signal transduction (e.g., hormone receptors)
• What are the strengths and weaknesses of the fluid mosaic model?

  Strengths:

  • Explains membrane fluidity and flexibility
  • Accounts for diverse protein functions

  
  

  Weaknesses:

  • Oversimplifies complex interactions
  • May not represent all membrane types accurately
• What are the implications of membrane disorders?

  • Increased cholesterol decreases fluidity
  • Impairs cell shape and oxygen transport
  • Affects overall cell function