chapter 12 (part 1 and 2)
osmosis result in___
a) volume change
b) pressure change
The fluids outside of plant cells is _____. The inside of the vacuole is ____. Thus water flows into the ____ and ____. This causes the cells to swell.
plant cell and vacuole
The loss of water in the whole plant causes the fluid outside of the cells to become hypertonic.
Water flows out of the cells, the cells shrink in a process called ___
what is plasmolysis?
water flows out of the cells, the cells shrink in a process called plasmolysis
What’s a contractile vaculoe, and how does it work?
it pumps water out of the cell.
to expel water, the vacuole uses exocytosis to remove the water
How does the cell force water into the contractile vacuole?
It expends a lot of energy actively pumping ions into the vacuole to make a hypertonic solution in it.
Compare and contrast the different means of solutes crossing membranes.
In the kidney, water is reabsorbed in responce to the hormone ___
vasopressin (antidiuretic hormone)
The presence of vasopressin promotes permeability and reabsorption. Aquaporins move from internal membranes to cell membrane… thus water is reabsorbed into the bloodstream.
in a hydrated state the aquaporins are located in ___
when vasopressin is present, it promotes ___ because auaporins move from ___ to ___ membrane.
internal membrane (so water passed into the bladder)
internal to cell membrane
Aquaporin channel regulate water flow
The flow is regulated by location of aquaporin proteins
3 types of gated channels
*gated bc they can be open or closed
1. Voltage gated channels (K+ channel)
2. Ligand-gated channels (neurotransmitters)
3. Mechano- gated channels
Ligand-gated ion channels
The binding of the neurotransmitter acetylcholine at certain synapses opens the Na+ channel. This initiates a nerve impulse or muscle contraction.
Mechanically-gated ion channels
Mechanically-gated ion channels
Sound waves bend cilia-like projections on the hair cells of the inner ear; the bending opens up ion channels, leading to the creation of
- How are K+ channels selective?
•Together with active transport, how are electrochemical gradients set up and dissipated in neurons? Which integral membrane proteins are involved in this process??
•The difference between indirect and direct active transport
•The importance of the Na+/K+ pump and how it works
•The relevance and functioning of the Ca2+ ATPase
•The difference between a symport and an antiport pump
•How the sodium/glucose co-transporter functions, and what other transporters are used to bring glucose into the bloodstream
active transport is:
•specific for a given chemical or ion
•coupled to the consumption of energy
•unidirectional (only pumped in one direction, as opposed to ion channels which flow in whatever gradient is set up)
•controlled by the cell
Active transport is bidirectional. Transporter or a pump can pump ions in both directions
The difference between indirect and direct active transport
Direct - transporter binds ATP directly and uses E of its hydrolysis
Indirect (cotransport) - transporter uses the E from ATP to set up a [c] gradient of one molecule. This E is used to transport another molecule.
How the sodium/glucose co-transporter functions, and what other transporters are used to bring glucose into the bloodstream
utilizes a sodium gradient to transport glucose against its concentration gradient
2 Na and one glucose transported together
glucose moves from ___ [c] in gut to __ [c] within the cells lining the gut.
energy source is ___
low [c], high [c] within the cells lining gut
The importance of the Na+/K+ pump and how it works
this sodium-potassium ATPase transporter uses ATP energy to pump out 3 Na and pump in 2K, against their [c] gradients
importance of Na/K ATPase
name 4 reasons
1) creates a net charge across plasma membrane - resting potential stage
2) accumulation of Na ions outside of the cell draws water out of the cell thus enabling to maintain osmotic balance
3) the Na ion gradient provide energy to run several types of indirect pumps
4) Fact: almost 1/3 of all the energy generated (ATP) in animal cells is used just to run this pump
The relevance and functioning of the Ca2+ ATPase
Ca pumps keeps the cytosolic Ca [c] ___
In resting muscle, there is a much __ [c] of ___ in ER than cytosol.
Ca via ___ pass into the ___ where it triggers muscle contartion
Energy comes from each molecule of ATP to pump 2 Ca ions
higher, Ca ions
facilitated diffusion, cytosol
Rapid movement of ions across membrane is ____
This rapid movement are from __ to __ [c]
The movement is done through ___
- The movement is non-selective
- each ion channel will pass only 1 type of ion
- the movement of ions id unidirectional
from high to low [c]
False, selective movement. K channels are selective for only K ions
False, the movement is bidirectional dependant on [c]
How are K+ channels selective?
selectivity based on stabilizing the pore structure in an ‘open’ state.
Na+ions are smaller and cannot stabilize the pore shape and are not passed.
Together with active transport, how are electrochemical gradients set up and dissipated in neurons? Which integral membrane proteins are involved in this process??
1) resting potential
2) Na/K pump set up electrochemical gradient
3) signal percieved in neuron body -- Na channels open -- Na flow from outside to inside - depolarization
4) K ion channels recognize the change in polarity -- open up K channels -- K from inside to outside
5) Ca channels recognize depolarization -- allow Ca into the cell - fusion of neurotransmitters
Which integral membrane proteins are involved in this process??
the sum of these signals determines whether the neuron will generate an action potential and send it down the axon to interact with other neurons.