Membranes and Transport

• Phospholipids are amphipathic molecules with hydrophilic phosphate-containing heads and hydrophobic fatty acid tails

  
• In a fluid bilayer, phospholipids are arranged in a double layer with hydrophilic heads facing outward and hydrophobic tails facing inward, creating a barrier impermeable to most water-soluble molecules
• In a bilayer vesicle, phospholipids form a closed sphere with hydrophilic heads facing outward and hydrophobic tails facing inward, creating a small water-filled compartment surrounded by a lipid bilayer
• In a "frozen" bilayer, phospholipids are in a solid, crystalline state, creating a barrier impermeable to all molecules
• The phospholipid bilayer, the main component of cell membranes, consists of a double layer of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward, providing a stable platform for the cell's proteins and lipids to function

  
• The cell membrane, composed of a phospholipid bilayer, separates the inside of the cell from the outside environment and contains proteins essential for cellular processes like transport, signaling, and adhesion

  
• The cell membrane, a selectively permeable barrier, is composed of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward, impermeable to most water-soluble molecules but allowing small hydrophobic molecules to pass through

  
• The sodium-potassium pump, found in the cell membrane of animal cells, maintains the balance of sodium and potassium ions across the membrane by using ATP to transport three sodium ions out and two potassium ions in

  
• <|> Facilitated diffusion is the passive transport of molecules across the cell membrane through transport proteins

  
• The image of a selectively permeable membrane shows the movement of water molecules, with a crenated red blood cell losing water and a normal red blood cell retaining its water content

  
• The image depicts plant cells in different states: normal, plasmolysis where the cell wall has shrunk due to water loss, and weakened turgor pressure where the vacuole is not full, reducing pressure on the cell wall

  
• Facilitated diffusion is the diffusion of solutes through transport proteins in the plasma membrane

  
• In a fluid bilayer, phospholipids are arranged with hydrophilic heads facing outward and hydrophobic tails facing inward, creating an impermeable barrier to most water-soluble molecules
• In a "frozen" bilayer, phospholipids are arranged in a solid, crystalline state, creating a barrier impermeable to all molecules
• The phospholipid bilayer, the main component of cell membranes, consists of a double layer of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward, providing a stable platform for cell proteins and lipids to function

  
• The cell membrane, composed of a phospholipid bilayer, is selectively permeable, containing proteins essential for transport, signaling, and adhesion, as well as glycolipids and glycoproteins important for cell-cell recognition and adhesion

  
• The sodium-potassium pump, found in the cell membrane of animal cells, maintains the balance of sodium and potassium ions across the membrane by transporting three sodium ions out and two potassium ions in using ATP

  
• In osmosis, water moves across a semipermeable membrane from a region with higher water concentration to lower water concentration, affecting cell volume and potentially leading to swelling or shrinking

  
• Active transport involves the movement of substances against a concentration gradient, requiring energy input, with primary active transport directly using ATP to fuel transport and secondary active transport indirectly using ATP
• Endocytosis, including non-specific (pinocytosis) and specific (receptor-mediated) types, involves substances being trapped in inward depressions from the plasma membrane and taken into the cell