Lecture 7 - Composition & Function of The Plasma Membrane Flashcards
What type of cells has a plasma membrane?
Eukaryotic Cells
What is the plasma membrane?
the boundary that separates the living cell from its surroundings. Essential for all cells
What is the role of the plasma Membrane?
it acts as a barrier to prevent the contents of the cell from escaping and mixing with molecules in the environment
What type of permeability does the plasma membrane have?
Selective permeability allowing some substances to cross it more easily than others
What are lipid bilayers?
when lipids are arranged in two closely apposed sheets in which proteins are embedded and some carbohydrates
What are the most abundant lipids in the plasma membrane?
Phospholipids
What are Glycolipids?
lipids containing sugars representing their hydrophilic head
What are the 4 major functions of membrane proteins?
- Transport of Molecules
- Enzymatic Activity
- Signal Transduction/cell communication
- Structural Support - attaches to the extracellular matrix
What are the 2 types of transport?
- Passive Transport
- Active Transport
What is passive transport?
When molecules move across the membrane without wasting energy from areas with high concentrations to a low concentration
What are the 3 types of Passive Transport?
- Diffusion
- Osmosis
- Facilitated Diffusion
What is Diffusion
free movement of molecules across the lipid bilayer from high to low concentration areas until equilibrium is reached
What is Osmosis
spontaneous movement of water across a semipermeable membrane from high water potential to a solution with low water potential
What is High water potential?
Low solute (water) concentration
What is low Water potential?
High solute (water) concentration
What is Osmotic pressure?
hydrostatic pressure is required to stop the net flow of water across a membrane - done by separating water potentials
What is Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
What is an isotonic solution?
solution with the same water concentration inside and outside the cell
What is a hypertonic solution?
solution with higher water concentration outside the cell than inside
How can osmosis pressure impact blood cells in hypertonic solutions?
change in osmotic pressure can cause cells to swell or shrink rapidly
What is Facilitated diffusion?
passive movement of molecules down a concentration gradient via transport proteins
What are the 3 transporter types for passive transport?
- Uniporters
- Symporters
- Antiporters
What is Endocytosis
Uptake (from outside to inside) of macromolecules and large proteins
What are the 3 types of Endocytosis?
- Phagocytosis
- Pinocytosis
- Receptor - mediated Endocytosis
What are the 3 types of Endocytosis?
- Phagocytosis
- Pinocytosis
- Receptor-mediated Endocytosis
What is Exocytosis
secretion / excretion (from inside to outside)
