Leftovers for first test Flashcards
What type(s) of transport require conformation of proteins
facilitated transport and active transport
What does it mean for a carrier protein to be saturated
there are too many solute molecules compared to carrier proteins
what does the green arrow in a diffusion diagram represent? What does a red arrow mean?
green arrow means direction of concentration gradient, red arrow means direction of transport
Define osmosis
diffusion of water across a selectively permeable membrane in response to concentration gradients
Do animal cells expend energy to counteract the inward and outward movement of water by osmosis
yes
How does water move in osmosis (from what kind of region to what kind of region)
it moves from a higher concentration of free water (less solute) to a region of lower concentration of free water (more solute)
Name a type of membrane we commonly see used to demonstrate osmosis
cellophane membrane
What is osmotic pressure
force needed to stop osmotic flow
what if a cell is in a hypotonic solution
the cell will swell and create pressure
In a hypotonic solution, what happens if the cell membrane is strong enough? Name an example
If Cell membrane is strong, cell reaches counterbalance of osmotic pressure driving water in with hydrostatic pressure driving water out. Like cell wall of prokaryotes, fungi, plants, and protists
In a hypotonic solution, what happens if a cell’s membrane is not strong enough? Name an example
The cell will swell and burst, like animal cells (they must be in isotonic environments)
What is Tonicity
property of solution with respect to a particular membrane
Define hypotonic
Solution surrounding a cell contains nonpentrating solutes at lower concentrations than the cell
define hypertonic and what happens to the cell
solution surrounding a cell contains nonpenetrating solutes at higher concentrations than the cell. Cell will shrivel
define isotonic
Concentration of nonpenetrating solutes of inside and outside the cell are balanced
Why do animal cells pump Na+ outside the cell
to keep fluids on either side of plasma membrane isotonic
What is the bilayer permeable to
gases (CO2, N2, O2), small hydrophobic and uncharged polar molecules (ethanol)
what is the bilayer slightly permeable to
urea and water
is glucose permeable to the membrane? How about fructose?
No, because even though they are uncharged polar molecules, they are too large
Are amino acids permeable to the membrane?
No
Is ATP permeable to the membrane?
No
Name 2 ways organisms maintain osmotic balance
Some cells use extrusion in which water is ejected through contractile vacuoles
Plant cells use turgor pressure to push cell membrane against cell wall and keep cell rigid
What is active transport
Moving substances against the gradient with a protein
Name 3 main functions of active transport
uptake of essential nutrients from fluid surrounding cells when concentrations are higher in cells,
removal of secretory or waste material even when…
maintenance of intracellular concentrations of H+ Na+ K+ Ca2+
What is membrane potential and how do you make it
Electrical charge difference (voltage) across a membrane using active transport of ions
What are some examples where we see membrane potential
neurons and muscle cells in response to a stimulus
What are the two types of active transport
Primary active transport and secondary active transport
What is primary active transport
Directly uses ATP to fuel active transport to move substances from low to high concentration with carrier proteins
Name an example of Primary active transport
Sodium potassium pump
How many potassiums and sodiums are involved in a single pump for the sodium potassium pump? Where does each molecule go
3 Na+ and towards outside of cell and 2 K+ going inside of cell
Go into detail of the steps of sodium potassium pump
1) carrier protein intially has higher affiniity for sodium and is open to inside the cell (inward facing conformation) so Na+ from inside attaches to protein
2) ATP is attached to protein hydrolysis occurs to release one phosphate and attach to the protein
3) protein conforms to outward facing, and now has a higher affinity for K+. Bc of this, Na+ is released out of cell and K+ out of cell goes into protein
4) dephosphorylation occurs and phosphate goes away and proteins goes back to inward face, releasing K+ into cell
Describe what happens in Calcium pump
Ca2+ from cytoplasm into cell exterior and from cytosol into vesicles of ER