EXAM 2 Flashcards
Passive Transport:
Definition: The movement of molecules across a cell membrane without the use of energy (ATP). It relies on the concentration gradient.
Examples:
Diffusion: Movement of oxygen and carbon dioxide across cell membranes.
Osmosis: Movement of water through a semipermeable membrane.
Facilitated Diffusion: Glucose transport into cells via glucose transporters.
Active Transport:
Definition: The movement of molecules across a cell membrane using energy (ATP), often against a concentration gradient.
Examples:
Sodium-Potassium Pump: Moves sodium ions out and potassium ions into the cell.
Endocytosis: Uptake of large particles or liquids into the cell.
Exocytosis: Expulsion of materials from the cell.
Cytosol:
Definition: The fluid component inside the cell, excluding organelles and other structures; part of the cytoplasm.
Example: The aqueous solution in which cellular processes occur, containing dissolved ions, nutrients, and proteins.
ECF (Extracellular Fluid):
Definition: The fluid environment outside cells, providing a medium for nutrient and waste exchange.
Examples:
Interstitial Fluid: Fluid between cells in tissues.
Plasma: The liquid component of blood.
Simple Diffusion:
Definition: Movement of molecules from an area of higher concentration to an area of lower concentration directly through the lipid bilayer without the aid of proteins.
Examples: Oxygen and carbon dioxide moving across cell membranes.
Scenario: Oxygen entering cells from the bloodstream due to higher concentration in blood.
Facilitated Diffusion:
Definition: Movement of molecules across a membrane via specific transmembrane integral proteins, down their concentration gradient.
Examples: Glucose entering cells through glucose transporters; ions passing through ion channels.
Scenario: Glucose uptake by muscle cells using GLUT4 transporters.
Primary Active Transport:
Definition: Movement of molecules against their concentration gradient using energy directly from ATP hydrolysis.
Examples: Sodium-potassium pump (Na⁺/K⁺ ATPase) that pumps sodium out and potassium into the cell.
Scenario: Maintaining low sodium and high potassium concentrations inside nerve cells.
Secondary Active Transport with Symport:
Definition: Transport of two different molecules in the same direction across a membrane, where one molecule moves down its gradient, providing energy for the other to move against its gradient.
Examples: Sodium-glucose co-transporter in intestinal cells.
Scenario: Glucose absorption in the intestines alongside sodium ions.
Secondary Active Transport with Antiport:
Definition: Transport of two different molecules in opposite directions across a membrane, where one molecule moves down its gradient, providing energy for the other to move against its gradient.
Examples: Sodium-calcium exchanger in cardiac muscle cells.
Scenario: Removal of calcium ions from heart cells while sodium ions enter.
Simple Diffusion:
Plasma Membrane Proteins Involved: None (directly through the lipid bilayer).
Energy Source: No energy required; relies on concentration gradient.
Direction: High to low concentration.
Type of Molecules Moved: Small, nonpolar molecules like oxygen (O₂) and carbon dioxide (CO₂).
Facilitated Diffusion:
Plasma Membrane Proteins Involved: Channel proteins or carrier proteins (e.g., glucose transporters, ion channels).
Energy Source: No energy required; relies on concentration gradient.
Direction: High to low concentration.
Type of Molecules Moved: Polar or charged molecules such as glucose and ions (e.g., Na⁺, K⁺).
Primary Active Transport:
Plasma Membrane Proteins Involved: Pump proteins (e.g., Na⁺/K⁺ ATPase).
Energy Source: Direct use of ATP.
Direction: Low to high concentration (against gradient).
Type of Molecules Moved: Ions like sodium (Na⁺) and potassium (K⁺)
Secondary Active Transport with Symport:
Plasma Membrane Proteins Involved: Co-transporter proteins (e.g., sodium-glucose co-transporter).
Energy Source: Indirect use of energy from the gradient of another molecule (usually Na⁺).
Direction: Both molecules move in the same direction; one down its gradient, the other against.
Type of Molecules Moved: Typically involves ions and nutrients, such as sodium (Na⁺) and glucose.
Secondary Active Transport with Antiport:
Plasma Membrane Proteins Involved: Exchanger proteins (e.g., sodium-calcium exchanger).
Energy Source: Indirect use of energy from the gradient of another molecule (usually Na⁺).
Direction: Molecules move in opposite directions; one down its gradient, the other against.
Type of Molecules Moved: Often involves ions, such as sodium (Na⁺) and calcium (Ca²⁺)
