Bio chap 5

• What do membranes separate in cells?

  Contents of cells from their environment
• What is the formation of separate membrane-bound areas in a cell called?

  Compartmentalisation
• Why is compartmentalisation important in cells?

  It allows specific conditions for cellular reactions
• What is the basic structure of membranes?

  Phospholipid bilayer
• How do phospholipids form the membrane structure?

  Hydrophilic heads sandwich fatty acid tails
• Why are phospholipids suited for cell membranes?

  They interact with aqueous environments
• How are channel proteins held in place?

  By interactions with the hydrophobic core
• What role do carrier proteins play in cells?

  They assist in passive and active transport
• Is a glycoprotein intrinsic or extrinsic?

  Intrinsic
• What is the form of a glycoprotein?

  Embedded in the cell surface membrane
• What roles do glycoproteins play in cells?

  Cell adhesion and chemical signaling
• What is cell signaling?

  Response elicited by chemical binding to receptors
• Give an example of cell signaling.

  Receptors for neurotransmitters
• What are glycolipids?

  Lipids with attached carbohydrate chains
• What can glycolipids be recognized as?

  Cell markers or antigens
• Where are intrinsic proteins located ?

  throughout both layers of phospholipid bilayer
• What do extrinsic proteins look like?

  Hydrophilic R-groups interact with polar heads
• What is cholesterol's role in membranes?

  Regulates membrane fluidity
• How does cholesterol increase membrane stability?

  By interacting with phospholipid heads and tails
• What is the fluid mosaic model?

  A flexible membrane with embedded proteins
• What is a glycoprotein?

  A protein with a branching carbohydrate portion
• What is the function of a glycolipid?

  Acts as a recognition site
• What is cholesterol's function in membranes?

  Provides stability and flexibility
• What are the two types of membrane proteins?

  Intrinsic and extrinsic proteins
• What is an intrinsic protein?

  Transmembrane proteins embedded in membranes
• How do intrinsic proteins stay in place?

  Hydrophobic R-groups interact with the membrane
• Name two intrinsic proteins involved in transport.

  Channel proteins and carrier proteins
• What do channel proteins do?

  Provide a hydrophilic channel for molecules
• How do cholesterol molecules prevent membranes from solidifying?

  By stopping phospholipids from grouping closely
• Why are membranes important for chemical reactions?

  Proteins must be in specific positions
• What are two factors that affect membrane structure?

  Temperature and presence of solvents
• How does increasing temperature affect a membrane?

  It increases kinetic energy and fluidity
• What happens to the membrane if the temperature continues to increase?

  The cell will break down completely
• What does the loss of membrane structure mean for permeability?

  It increases permeability, allowing easier particle crossing
• What happens to carrier and channel proteins at higher temperatures?

  They will denature, affecting membrane permeability
• What is an example of a non-polar organic solvent?

  Benzene
• What do organic solvents do to cells?

  They dissolve membranes, disrupting cells
• How do pure or strong alcohols affect the body?

  They are toxic and destroy cells
• What happens when non-polar alcohol molecules enter the cell membrane?

  They disrupt the membrane structure
• What happens to the membrane when it is disrupted?

  It becomes more fluid and permeable