Midterm 2 Flashcards
Que signifie ‘’ the lipid-bilayer is SEMI-PERMEABLE’’ ?
Que la membrane est perméable (permissive) à certaines substances, mais pas toutes.
V\F
The more charged the molecule, the more easily it crosses the lipid bilayer.
F
The more charged the molecule, the less easily it crosses the lipid bilayer.
Place ces substances en ordre de facilité à traverser la membrane cellulaire:
H2O, sucrose, Ca2+, O2.
- O2 (Hydrophobic)
- H2O (Small Uncharged Polar)
- Sucrose (Large Uncharged Polar)
- Ca2+ (Ions)
What is the name of a transporter that can bind to a specific solute molecule and allows it to cross the cellular membrane?
A membrane protein
What kind of links form membrane proteins?
- Temporary Hydrogen bond
2. Electrostatic interactions
Is there binding to the solute molecules in channel proteins
?
No. Channel proteins simply keeps a hole open. NO BINDING.
Without energy input, in what direction does the solute move?
Which direction it goes depend on the CONCENTRATION GRADIENT (from high to low concentration).
What are the 3 part of passive transport and what characterized them?
- Simple diffusion
- Channel mediated
- Transport mediates
NO ENERGY INPUT (from high to low concentration)
What allows active transport?
To move from low to high concentration
If the inside of the cell is positive, which of the cation or the anion would move inside more easily?
The negative anion , because it would be attracted by the positive charge.
Is there a maximum to transport rate?
There is a maximum to transport rate for transporters, because they can only transport a maximum number of molecules at a time. However, diffusion rate is linear, it only depends on gradient concentration.
What are the 3 most types of active transport?
I. Coupled transport: uses the concentration gradient of a solute to move another solute
II. ATP diven
III Light
What is the name type of a simple transporter that moves a single solute molecule?
Uniport
What is the name type of a transporter that moves 2 molecules at a time in the same direction?
Coupled-SYMPORT
What is the name type of a transporter that moves 2 molecules in opposite direction?
Coupled-ANTIPORT
What is the occluded form?
Meaning that the transporter is closed
How does the glucose moves trough the membrane?
The glucose move through COUPLED-SYMPORT movement with a coupled-transporter that uses (Na+)SODIUM
How is the sodium transported in the extracellular fluid?
The sodium is actively transported out of the cell in a Sodium-Potassium ANTIPORTER that uses ATP
Name the molecules used in those type of ATP transporters. I. P-type pump II. ABC transporters III. V-type proton pump IV. F-type ATP synthase
I. P-type pump: IONS out of the cells
II. ABC transporters: wide variety of small molecules
III. V-type proton pump: protons, ATP (hydrolysis)
IV. F-type ATP synthase: protons (synthesize ATP)
What type of ATP transporters is able to move anti-cancer drugs?
ABC transporters
What is the role of the P-type calcium transporter in the ER muscle cells?
To bring the calcium ions OUT of the sacroplasmic reticulum of the cell while using ATP (symporter of calcium and protons)
Name 2 exemple of P-types transporters
I. Calcium SYMPORTER of the ER of muscle cells
II. Sodium-Potassium ANTIPORTER
How many molecules of ATP usually use ATP transporters?
2 ATPs
What is the name of the part of a channel proteins that only allows some molecules in the channel?
The selectivity filter
Is the channel protein always open?
No. It can be closed or open
What are the different signals that channel proteins can respond to?
I. Voltage: voltage-gated channel
II. Ligands (small molecules) IN or OUT - ligand-gated channels (extra\intra cellular)
III. Physical\mechanical movement -mechanically gated channel
What is the particularity of the alpha helix in the voltage gated potassium channel?
The alpha helix is slightly positive at one end, and slightly negative at the other (POLAR)
What are the 4 important parts of the voltage-gated potassium channel?
- Alpha helices
- Central pore
- Vestibule
- Selectivity filter
Is the voltage gated potassium channel permeable to water?
No. The selectivity filter is too small for water to pass through.
Is the vestibule and the pore of the voltage gated potassium channel selective?
No. They allow for different types of ions and water to get in until they reach the selectivity filter.
How come the potassium can passe the selectivity filter of the voltage fated potassium channel but not the sodium?
Because potassium is able to make transcient 4 H bounds in the selectivity filter, wich removes water, but not sodium (too small). Therefore the energy required to remove water is too low.
How works the mechanosensor in bacteria that responds to osmotic presur?
Water entering the cell make the volume increase, which make the membrane stretched and opens the channel.
What are the 4 importants part in the voltage gated sodium channel in the neurones?
- Ion channel
- Selectivity filter
- Voltage sensors
- Inactivation domain
T\F
The alpha helices in neurones move in response to a change in voltage
T
What is the normal voltage difference across the neurone membrane?
-60 mV to -70 mV
What is the level of mV where the voltage triggers the channel to open and autorise ion flow across the membrane in neurones?
-55 mV
When is voltage gated sodium channel open?
When the extracellular space is negative and the cytosol positive.
What are the name of the channels in the post-synaptic membrane that respond tu neurotransmitters?
Ligand-gated ion channels.
How many subunits is there in the ligand-gated ion channel of the post synaptic membrane?
5
What does the selectivity filter passes in the post synaptic membrane?
Positive ions
