1.4 Flashcards
(30 cards)
define passive movement
movement that uses existing kinetic energy in the form of random motion
- existing potential energy in the form of charge or concentration gradient
- thus requires no energy input
define active movement
- movement that requires extra energy input
- to move against charge or concentration gradients (low to high)
what are the 3 main passive movement manifests for particles?
- simple diffusion
- facilitated diffusion
- osmosis
describe simple diffusion and what it typically occurs with
- the net movement of particles from an area of high concentration to an area of low concentration (down the conc gradient)
- typically occurs with small uncharged or hydrophobic particles across a semi-permeable membrane
describe facilitated diffusion and what it typically occurs with
- net movement of particles form an area of high conc to an area of low conc
- via a channel or passive carrier proteins
- typically occurs with larger or charged particles
give an example of when simple diffusion occurs
- the movement of oxygen and carbon dioxide across the cell membrane
what do carrier proteins normally transport?
- lipids
- insoluble molecules
what do channel proteins normally transport?
- small polar molecules
- ions
what causes the potassium channels to close?
when its internal charge is negative relative to outside
what causes the potassium channels to open?
when a neuron fires a signal, its internal charge becomes positive relative to the outside
how does potassium ions leave the channel?
- potassium ions undergo facilitated diffusion to leave
how does potassium ions get back into the cell?
- occurs through active transport
what are the 2 types of active carrier proteins?
- symporters
- antiporters
what are symporters?
- carrier proteins
- that transports 2 molecules in the same direction
- co-transportation
what are antiporters?
- carrier proteins
- that transports 2 molecules in the opposite directions
- often done by using ATP to open the carrier to the inside or the outside of the cell
give an example of a symporter
- the glucose-sodium carrier protein
- present in the small intestine and kidney
give an example of an antiporter
- Na+/K+ ATPase pump
wtf is phosphorylation and what does it cause?
- when ATP binds a phosphate to the Na+/K+ pump
- phosphorylation causes the pump to change conformation to now open to the outside of the neuron
what enters and what leaves the Na+/K+ pump?
- 3 sodium ions exits the pump by binding to the pump’s binding site
- the bound phosphate group detaches from the pump causing it to return to its original conformation
- 2 potassium ions enters through the pump
define vesicular transport
- movement of large material or materials in bulk
- into and out of the cell by using vesicles
what are vesicles and how are they formed?
- spheres of phospholipid bilayer
- formed when the pinching off the plasma membrane
what is endocytosis?
- the transport of large materials or materials in bulk into the cell
describe the process of endocytosis
- materials come near the plasma membrane
- plasma membrane invaginates to engulf the materials
- once engulfed, the plasma membrane pinches off to form a vesicle, which moves through the cytoplasm to its end destination
what is exocytosis?
- the transport of large materials or materials in bulk out of the cell
