plasma membrane

• What does the term "plasma membrane" refer to?

  Cell membranes and organelle membranes
• What model describes the structure of plasma membranes?

  Fluid mosaic model
• What does the "fluid" part of the fluid mosaic model refer to?

  Movement of molecules within the membrane
• What are the main components of the plasma membrane?

  Phospholipids, proteins, cholesterol
• What is the arrangement of phospholipids in the bilayer?

  Hydrophilic heads face outside, tails inside
• What charge does the phosphate group in the phospholipid head have?

  Negative charge
• Why are the fatty acid tails of phospholipids hydrophobic?

  They lack charges and repel water
• What distinguishes saturated fatty acids from unsaturated fatty acids?

  Saturated has no double bonds; unsaturated does
• What role does cholesterol play in the plasma membrane?

  Restricts lateral movement of molecules
• How does cholesterol affect membrane fluidity at high temperatures?

  Reduces fluidity, making it more rigid
• What are peripheral proteins?

  Proteins that do not span the membrane
• What is the function of integral proteins?

  Span the entire width of the membrane
• What do glycoproteins and glycolipids do?

  Serve as recognition receptors
• How do channel proteins function?

  Allow water-soluble ions to pass through
• What is the role of carrier proteins?

  Transport larger molecules across the membrane
• What does "partially permeable membrane" mean?

  Only certain molecules can diffuse through
• Which types of molecules can diffuse through the phospholipid bilayer?

  Lipid-soluble and small molecules
• Which hormones can diffuse through the membrane?

  Estrogen and small gases
• What types of substances cannot pass through by simple diffusion?

  Larger water-soluble and polar substances
• Why can't glucose pass through by simple diffusion?

  It is too large to diffuse
• What is the role of phospholipids in forming the bilayer?

  They create a barrier with hydrophilic heads and hydrophobic tails
• Why is the negative charge on the phosphate group significant?

  It makes the head hydrophilic and attracts water
• What is the importance of membrane fluidity for cell function?

  It allows movement and flexibility of membrane components
• What are the specific functions of peripheral and integral proteins?

  Peripheral proteins provide support; integral proteins transport
• How do glycoproteins and glycolipids function in the membrane?

  They act as recognition sites for signaling
• What is the process of how channel and carrier proteins transport substances?

  Channel proteins allow ions; carrier proteins change shape
• What are the implications of a partially permeable membrane on cellular transport?

  Only specific molecules can enter or exit
• What types of molecules can diffuse through the membrane?

  Lipid-soluble and small non-polar molecules
• What types of molecules cannot diffuse through the membrane?

  Larger polar and water-soluble substances
• Why can't glucose pass through by simple diffusion?

  It is too large to diffuse through