Biology - Biological membranes

• Active transport

  The active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP
• Amphipathic

  A molecule with both hydrophobic and hydrophilic parts.
• Cell lysis

  The bursting of a cell, particularly after the uptake of too much water into an animal cell through osmosis.
• Cholesterol

  A mostly hydrophobic molecule that sits in the hydrophobic portion of the membrane and regulates membrane fluidity.
• Crenation

  The shrinking of a cell when placed in a hypertonic solution due to large amounts of water moving out of the cell through osmosis. Endocytosis: The bulk uptake of substances into a cell by i
• Endocytosis

  The bulk uptake of substances into a cell by invagination of the membrane to form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP.
• Exocytosis

  The bulk transport of substances out of a cell using a vesicle that fuses with the plasma membrane using energy in the form of ATP.
• Facilitated diffusion

  The net movement of substances from a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy.
• Fluid mosaic model

  A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins.
• Hydrophilic

  A molecule which is attracted to water.
• Hydrophobic

  A molecule which repels water.
• Integral membrane protein

  A type of protein bound to the membrane with strong interactions.
• Osmosis

  The net movement of water molecules across a partially permeable membrane from a region of high water potential to a region of lower water potential without the use of energy.
• Peripheral membrane protein

  A type of protein that is weakly bound to the surface of the membrane
• Phagocytosis

  The ingestion of solid material (particularly pathogens and foreign material) by phagocytic cells.
• Phospholipid

  A type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group.
• Pinocytosis

  The bulk uptake of liquids into the cell using energy in the form of ATP.
• Plasmolysis

  The effect produced by placing plant cells in a hypertonic solution causing the cell to shrivel from water loss, resulting in the membrane pulling away from the rigid cell wall
• Simple diffusion

  The spreading out of substances from a high concentration to a lower concentration (down their concentration gradient) without the use of energy.
• Turgid

  A term used to describe a cell that is swollen due to large amounts of fluid uptake
• Water potential

  A measure of the tendency of water molecules to move from one area to another measured in kilopascals (kPa) and given the symbol Ψ.