BIOL1025

• What does the cell membrane delimit?

  A semi-autonomous functional unit
• How does the cell membrane control movement?

  It regulates ions and molecules entering and exiting
• What is one function of the cell membrane?

  Protection from the external environment
• What role does the cell membrane play in cell signaling?

  It facilitates communication between cells
• Where does the polar hydroxyl head group of cholesterol insert?

  Close to the polar group of phospholipids
• How does cholesterol affect membrane fluidity at low temperatures?

  It increases spacing between hydrocarbons
• What happens to cholesterol's effect on fluidity at high temperatures?

  It pulls hydrocarbon tails together, decreasing fluidity
• What happens to phospholipids at lower temperatures?

  They move less and pack tighter
• What state do saturated hydrocarbons form at lower temperatures?

  A crystalline state
• How do unsaturated hydrocarbons affect membrane fluidity?

  They create greater spacing, increasing fluidity
• What is the composition of the lipid bilayer?

  Embedded or attached proteins and lipids
• What percentage of the membrane mass do lipids make up?

  Around 50%
• How many lipid molecules are in a small animal cell?

  Around 1 billion
• What property do lipids exhibit in the membrane?

  They are self-organising
• What are the two parts of amphiphilic molecules?

  Hydrophobic tail and hydrophilic head
• What effect do double bonds have on fatty acid tails?

  They create a kink in the tail
• How does tail length affect lipid packing?

  It influences the fluidity of the membrane
• What type of movement do phospholipids exhibit laterally?

  Rapid lateral movement
• What is flexion in the context of phospholipid movement?

  Movement of hydrocarbon tails
• What does rotation refer to in phospholipid movement?

  Rotation of the phospholipid
• What is flip-flopping in phospholipid movement?

  Movement between the planes
• Vesicles are small membranous sacs that bud off from one organelle and fuse with another.
• Protein secretion involves the movement of newly synthesized proteins from the ER to other cellular compartments or outside the cell through vesicular transport.
• The endomembrane system is involved in the synthesis, modification, sorting, transport, storage, and degradation of proteins.
• Endocytosis involves vesicle formation at the plasma membrane, engulfing extracellular material inside the cell.
• Exocytosis involves vesicle fusion with the plasma membrane, releasing their contents outside the cell.
• The Golgi apparatus modifies, sorts, packages, and transports proteins and lipids within cells.
• Phagocytosis is a form of endocytosis where large particles or pathogens are ingested by specialized cells called phagocytes.
• Transcytosis is a type of endocytosis where molecules pass through the cell via vesicles.
• Pinocytosis involves the uptake of fluids and dissolved substances by invagination of the plasma membrane.
• Receptor-mediated endocytosis is a specific process involving ligand binding to receptors on the surface of cells.
• Mitochondria generate ATP through aerobic respiration.
• Pinocytosis is a type of endocytosis that involves the uptake of small amounts of fluid into the cytoplasm.
• Phagocytosis involves the ingestion of large particles such as bacteria or dead cells by specialized white blood cells called macrophages.
• Peroxisomes contain oxidative enzymes used for detoxification and metabolism.
• Pinocytosis involves the uptake of fluids and solutes into the cell via invagination of the plasma membrane.
• Lysosomes contain hydrolytic enzymes used for digestion and recycling of macromolecules.
• Pinocytosis is a type of endocytosis where small amounts of fluid from the external environment are taken up into the cell.
• Phagocytosis involves the ingestion of large particles by specialized immune cells called macrophages.