topic 2.5

• what is activ 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.
• define amphipathic?

  A molecule with both hydrophobic and hydrophilic parts
• What is cell lysis?

  The bursting of a cell, particularly after the uptake of too much water into an animal cell through osmosis
• What is cholesterol?

  A mostly hydrophobic molecule that sits in the hydrophobic portion of the

  membrane and regulates membrane fluidity.
• what is 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
• What is 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.
• What is 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.
• what is 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
• What is the fluid mosaic model?

  A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins
• Define hydrophylic?

  A molecule which is attracted to water
• define hydrophobic?

  A molecule which repels water
• What is an integral membrane protein?

  A type of protein bound to the membrane with strong

  interactions
• What is 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
• What is a peripheral membrane protein?

  A type of protein that is weakly bound to the surface of the

  membrane.
• What is phagocytosis?

  The ingestion of solid material (particularly pathogens and foreign material)

  by phagocytic cells
• What is a phospholipid?

  A type of lipid formed by the condensation of one molecule of glycerol, two

  molecules of fatty acid and a phosphate group.
• What is pinocytosis?

  the bulk uptake of liquids into the cell using energy in the form of ATP.
• What is 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.
• What is simple diffusion?

  The spreading out of substances from a high concentration to a lower

  concentration (down their concentration gradient) without the use of energy
• Define turgid?

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