Chapter 3 vocab Flashcards
Permeability
Determines what moves in and out of a cell, and a membrane that restricts movement is selectively permeable
Permeability restricts materials based off
- size
- electrical charge
- molecular shape
- lipid solubility
Passive processes
no energy required
active processes
requiring energy
types of transport processes
- diffusion and osmosis (passive)
- carrier-mediated transport (passive or active)
- vesicular transport (active)
Diffusion
Net movement of a substance from area of higher concentration to area of lower concentration
Concentration gradient
Difference between high and low concentrations of a substance
Factors influencing diffusion
- Distance the particle has to move
- Ion and molecule size (smaller=faster)
- Temp (hotter=faster)
- conc. gradient (steeper grad.=faster diff)
- Electrical forces (opp attract, likes repel)
Simple diffusion
- lipid soluble compounds
- Dissolved gases
- water molecules
Channel mediated diffusion
- water-soluble compounds and ions
- affected by size, charge, and interaction with cell walls
Osmosis
- diffusion of water across a selectively permeable membrane
- water molecules diffuse across a membrane toward the solution with more solutes
osmotic pressure
The force with which pure water moves into a solution as a result of solute conc.
Hydrostatic pressure
pressure needed to block osmosis
Aquaporins
Abundant water channels that water can use to cross through a membrane
osmopolarity (osmotic conc)
Total solute conc in a solution
Tonicity
How a solution affects cells
Isotonic solution
Does not cause osmotic flow
Hypotonic solution
Lower solute conc than the cell
Hypertonic solution
Higher solute conc than the cell
Hemolysis
Rupture of a cell in a hypotonic solution. Gains water
Crenation
Loss of water and shrinkage of a cell in a hypertonic solution
Carrier-mediated transport
Proteins transport ions or organic substrates across plasma membrane
Aspects of carrier-mediated transport
- specificity
- saturation limits
- regulation
Symport (cotransport)
Two substances move in the same direction at the same time (carrier-mediated)
Antiport (countertransport)
One substance moves in while another moves out
Facilitated diffusion
Carrier proteins transport molecules too large to fit through channel proteins. Passive
Receptor site
Where the molecule binds on a carrier protein
Active transport
Move substrates against conc. gradients
Ion pumps
Move ions (Na,K,Ca,Mg). Active
Exchange pumps
Move two ions in opposite directions at the same time
Primary active transport
Pumping solutes against a conc. gradient using ATP
Sodium-potassium exchange pump
One ATP powers the movement of 3 sodium ions (Na) out, and 2 potassium ions (K) in
Secondary active transport
ATP required to establish a conc. gradient of one substance in order to passively transport another. (ex. Na conc. gradient drives glucose transport into cells)
Vasicular transport (bulk transport)
Materials move into or out of a cell in vesicles
Endocytosis
The importation of extracellular materials packaged within vesicles, which requires ATP
Receptor-mediated endocytosis
Receptors (glycoproteins) bind target molecules (ligands)
Clathrin-coated pits
Where receptors and their ligands migrate to in plasma membrane to enter cell in Receptor-mediated endocytosis.
Caveolae
Small indentations with which some receptors are associated with in receptor-mediated endocytosis
Pinocytosis
Endosomes “drink” extracellular fluid
Phagocytosis
Large objects engulfed in phagosomes
Pseudopodia
Cytoplasmis extensions used in phagocytosis
Exocytosis
Granules or droplets are released from the cell as a vesicle fuses to plasma membrane
Potential difference
When positive and negative charges are separated in membrane potential
Membrane potential
Unequal charge across the plasma membrane
Resting membrane potential
-10mV to -100 mV (depends on cell type)
