Plasma Membrane• Boundary that separates the living cell from it’s non-living surroundings.• Phospholipid bilayer• Amphipathic - having both: hydrophilic heads hydrophobic tails Phospholipid• ~8 nm thick
Plasma Membrane - cont.• Controls traffic into and out of the cell with phospholipids and transport proteins.• Selectively permeable Transport protein
Selective Permeability• The property of biological membranes which allows some substances to cross more easily than others.
Fluid Mosaic• 1972 - Singer and Nicolson called the membrane a “Fluid Mosaic Model”.• Mosaic: different proteins embedded in the phospholipids.• Fluid: proteins and phospholipids can move freely in the membrane.
Transport Proteins• Transports molecules or ions across biological membranes• 3 types of transport proteins: proteins 1. uniport 2. symport 3. antiport
Uniport Transport Protein• Carries a single solute across the membrane.extracellular intracellularfluid fluid
Symport Transport Protein• Translocate 2 different solutes simultaneously in same direction. extracellular intracellular fluid fluid
Antiport Transport Protein• Exchanges 2 solutes by transporting them in opposite directions. directions extracellular intracellular fluid fluid
Diffusion• The net movement of a substance (molecules) down a concentration gradient from an area of high concentration to an area of low concentration. concentration• passive transport: NO energy is expended.• facilitated diffusion: type of passive transport which uses transport proteins.
Osmosis• The movement of water across selectively permeable membranes. membranes• The water moves from a high concentration to low concentration. concentration
Question: What’s in a Solution?Answer:• solute + solvent → solution• NaCl + H20 → saltwater
Hypertonic• A solution with a greater solute concentration compared to another solution. solution 3% NaCl solution 97% H2O 5% NaCl 95% H2O Red Blood Cell
Hypotonic• A solution with a lower solute concentration compared to another solution. solution 3% Na solution 97% H2O 1% Na 99% H2O Red Blood Cell
Isotonic• A solution with an equal solute concentration compared to another solution. solution 3% Na solution 97% H2O 3% Na 97% H2O Red Blood Cell
Movement of H2O• Water will “ALWAYS” diffuses down a concentration gradient from a HYPOTONIC solution to a HYPERTONIC solution. solution“ALWAYS REMEMBER”• HYPOTONIC → HYPERTONIC
Animal Cells• Animal cells placed into a hypotonic solution will HEMOLYSIS (EXPLODE).• Animal cells placed into a hypertonic solution will CRENATE (SHRIVEL). Hemolysis Crenation Red Blood Cells
Plant Cells• Firmness or tension (vacuole full) that is found in plant cells (cell wall) that are in a hypotonic environment is called TURGID.• This process is called TURGOR PRESSURE. Water Water Central Vacuole Cell Wall Water
Plant Cells• When the plasma membrane pulls away from the cell wall (vacuole empty) in a hypertonic environment (loss of water) is called PLASMOLYSIS. PLASMOLYSIS Water Water plasma membrane Cell Wall Water
Active Transport• The movement of molecules (small or large) across the plasma membrane in which energy (ATP) is required. required• Examples:1. Sodium (Na) - Potassium (K) Pump2. Exocytosis3. Endocytosis
Sodium-Potassium Pump• The mechanism that uses energy (active transport) released from splitting ATP to transport Sodium (Na+) out of and Potassium (K+) into cells. extracellular intracellular fluid fluid K+ K+ Na+ Na+
Question:• How are large molecules transported into and out of the plasma membranes?