Unit 2 Membrane Transport Flashcards
phospholipid bilayer
head: hydrophilic & polar
fatty acid tails: hydrophobic & nonpolar
How would you describe the permeability of the plasma membrane?
semi permeable
what does the plasma membrane allow to pass through it?
- small
- nonpolar
- uncharged
what does the plasma membrane NOT allow to pass?
ions/charged molecules
transmembrane protein
channels or transporters that INCREASE the permeability of the plasma membrane
Vesicular transport
macromolecules pass via this method
What are the two major groups of membrane transport
passive and active
what are the types of passive transport
- simple diffusion
- facilitated diffusion
- osmosis
what is the gradient of passive transport
HIGH TO LOW CONCENTRATION/ WITHOUT THE USE OF ATP/ WITH OR DOWN THE GRADIENT
What are the types of active transport?
- primary active
- secondary active
- vesicular transport
what is the gradient of active transport
LOW TO HIGH CONCENTRATION/ WITH ATP/AGAINST OR UP THE GRADIENT
what is a concentration gradient
the difference between the amount of a chemical on one side of the membrane in comparison to the other
what is the difference between the concentration gradient inside and outside of the cell
OUTSIDE THE CELL: more O2 & Na ions
INSIDE THE CELL: more CO2 & K ions
what is an electrical gradient
the difference between ions or charges between one side of the membrane and another
what determines an electrical gradient
membrane potential
what is the difference between the electrical gradient outside and inside the cell?
INSIDE THE CELL is more NEGATIVE
OUTSIDE THE CELL is more POSITIVE
ELECTROCHEMICAL GRADIENT
electrical gradient + chemical gradient
Simple diffusion
The random mixing of particles by stirring causes the articles to spread and produces kinetic energy
what is the concentration gradient of simple diffusion
high to low
what diffuses in simple diffusion
the SOLVENT & SOLUTE
What factors affect the rate of diffusion?
- Steeper Gradient: more significant difference in concentration
- Higher temperature: heat generates more kinetic energy
- Large membrane surface area
- Distance of diffusion
- smaller particle
what does diffusion look like through the lipid bilayer?
- nonpolar
- hydrophobic
through what form of transport does GAS EXCHANGE occur?
diffusion
What are the 3 types of ion channels
- leakage
- voltage-gated
- ligand
Leakage channels
gates open and close (passing of Na+ and K+)
Voltage-gated channels
open in response to membrane potential (passing of Na+ and K+)
Ligand-gated channels
open and close in response to chemical stimuli (neurotransmitters, hormones, or other ions)
Why is facilitated diffusion needed within passive transport?
solute is too polar
what are the general steps of facilitated diffusion?
- solute binds to the specific transporter protein
- transporter makes a CONFORMATIONAL CHANGE
- the solute moves across the membrane and is released on the other side of the membrane
what solutes move via facilitated diffusion?
- glucose
- urea
- fructose
- galactose
- vitamins
Osmosis
net movement of SOLVENT through a selectively permeable membrane
Hydrostatic Pressure
pressure that the water column exerts
what does hydrostatic pressure prevent
prevents water from diffusing through the membrane
osmotic pressure
applied pressure by the solvent or another force when they are not permeable to the membrane
Tonicity
how the osmolarity of an outside solution effects the cell volume
HYPERtonic
tonicity of solution > tonicity of cell
what happens to a cell when in a HYPERtonic solution
CRENATION: the cell shrinks
HYPOtonic
tonicity of solution < tonicity of cell
what happens when a cell is in a HYPOtonic solution
HEMOLYSIS: the cells wells and burst
ISOtonic
tonicity of solution = tonicity of cell
what happens when a cell is placed in an ISOtonic solution?
stays the same
what mechanism is used in Primary Active Transport
Sodium Potassium Pump (Na/K Pump)
Where does primary active transport get its energy to make the pump work?
energy comes from ATP, and it changed the shape of the transporter protein that pumps a substance across the membrane
What does the sodium-potassium pump strive to maintain in primary active transport
LOW Na+ and HIGH K+ in cytosol (inside the cell)
secondary active transport
energy stored in the Na+ or H+ concentration gradient used to drive other substances against their gradient = ION GRADIENTS
SYMporter
aka cotransporters; move substrates in the same direction
ANTIporters
aka exchangers; move substrates in the opposite direction
what ion begin the process of secondary transport
SODIUM ION
Transport Vesicles
a sac; site of budding
what are the 2 ways in which vesicles perform
Endocytosis and Exocytosis
ENDOcytosis
bring INTO the cell
what are the two types if endocytosis
phagocytosis and pinocytosis
phagocytosis
cell eating
what performs phagocytosis
WBCs and macrophages
Pinocytosis
cell drinking
Exocytosis
release something from the cell
where do these vesicles used form for exocytosis
inside the cell, and they fuse to the cell membrane to release contents
what kinds of things perform exocytosis
digestive enzymes, hormones, neurotransmitters and waste products
diffusion
passing from one side of the membrane to another
do we need ATP for ion channels
NO ATP NEEDED
What is the gradient of Na and K in primary active transport?
LOW TO HIGH/ AGAINST/ UPHILL/ UP
what is the main role of the sodium-potassium pump
to maintain gradient equilibrium
in secondary active transport, what is the gradient
sodium is going with while potassium eventually goes against using the energy from the start
Example of pinocytosis
absorption of nutrients from food
