Lec 2 Flashcards
A cell membrane is composed of phospholipids and contains no proteins. This membrane is impermeable to:
- water
- ions
- water and ions
- the membrane is permeable.
Answer: 3. water and ions.
Membrane transport depends on the presence of which type of membrane proteins?
Integral Membrane Proteins
Integral Membrane proteins have membrane spanning a-helical domains of how many amino acids?
20 amino acids
Integral Membrane Proteins can have multiple membrane spanning domains.
T or F?
True
Integral Membrane Proteins cannot be linked to membrane phospholipids.
T or F?
False: They can be linked via oligosaccharide.
Integral Membrane Proteins can be linked to fatty acids or prenyl groups.
T or F?
True
What type of proteins can be “non-covalently bound with integral proteins” ?
Peripheral Proteins
What are the two types of membrane transport?
Active Transport
Passive Transport
- Passive Transport or “Flow” can be acheived through what three types of integral protein transport structures?
- pores or leak channels
- channels
- carriers
Which passive transport structure is the fastest?
Which is the slowest?
pres or leak channels - fastest
carriers - slowest
Which passive transport structure is never fully open?
carriers - gated by 2 doors that are never open at the same time
Which passive transport structure can be closed?
channels - they are gated.
Which passive transport structure undergoes simple diffusion, where Net flux = JX ?
pores and channels - have a linear relationship between net flux and ion concentration.
Whats the title of the experiment that led to the discovery of transport proteins by injecting a the gene for a protein into a frog ocyte? This led to the swelling and exploding of the ocyte.
The Exploding Cell Assay
Which type of transport structure reaches a maximum net influx at an unlimited concentration of ions?
Carriers : creates Carrier Mediated or Facilitated Diffusion.
What are the two subcategories of Active Transport?
Primary
Secondary
Na+/K+ pump is an example of what subtype of Active Transport?
Primary Active transport
In a Na+/K+ Pump, How many ions of each are pumped into the cell membrane, and how many are pumped out?
Na+ = __ pumped in or out?
K+ = __ pumped in or out?
3 Na+ out
2 K+ in
Helps maintain standard gradient of higher K+ inside the cell and higher Na+ outside the cell.
What type of secondary active transport structure pumps ions of opposite charge in the same direction?
Cotransporter or Symporter
What type of secondary active transport structure pumps ions (with the same charge) in opposite directions?
Exchangers or Antiporters
Passive transport is primarily responsible for the maintenance of differences between the concentrations of key ions and is required for resting membrane potential and action potential.
T or F?
False : Active Transport is primarily responsible.
What are the two types of secondary active transport structures?
Cotransporter/Symporter
Exchangers/ Antiporters
Na+ is about 145 mM inside or outside the cell?
outside
K+ is about 120-155 mM inside our outside the cell?
inside
Voltage gated ion channels are made up of a single subunit or a pseudo-subunit protein.
T or F?
False - channels are made up of multiple subunits or pseudo-multimeric proteins
Voltage gated ions channels are made up of _______ a-helices.
a. hydrophobic
b. hydrophilic
c. amphipathic
d. ionic
amphipathic a-helicies
In voltage gated ion channels, the parts of the molecule that face the inside of the “pore” have _____ surfaces.
a. hydrophobic
b. hydrophilic
c. amphipathic
d. none of the above
hydrophilic - to allow passage of charged ions.
