E2 Chapter 7: Membrane Structure and Function Flashcards
Exam 2
The two staple ingredients in making a cell membrane are
- Proteins
- Lipids
Basic unit of life
Cells
What forms the boundary between interior region and outside region of the cell?
Plasma membrane
The interior region contains __________, which is made up of ____________
Cytoplasm; cytosol
The phospholipid head is ____________ and _______ water
Hydrophilic; and loves water (polar)
The fatty acid tails are __________ and ___________ water
Hydrophobic; hate water (nonpolar)
Just like the phospholipid bilayer, membrane proteins are _______________, meaning they contain both hydrophobic and hydrophilic parts
amphipathic
The plasma membrane is slightly permeable. This is due to what reasons? (2)
- Hydrophilic and hydrophobic DO NOT interact
- The interior of plasma membrane is nonpolar/hydrophobic
What is the currently accepted cell model called?
Fluid mosaic model
A membrane is held together by ______________, which is weaker than what type of bonding?
hydrophobic interactions; covalent bonding
The membrane exhibits ________________ ___________, which is allowing certain things to cross compared to others
Selective permeability
What are easy to diffuse across the membrane?
Small nonpolar/hydrophobic molecules
What is the diffusion of small nonpolar molecules called?
Simple diffusion
Why do certain molecules simple diffuse? (2)
- Can interact with a hydrophobic interior
- Can squeeze past the membrane easily
What molecules do not diffuse easily?
Hydrophilic/polar molecules
Large molecules
Why do certain molecules not pass through the membrane easily?
- Polar does not readily interact with hydrophobic interior
- Too big to squeeze through
What do polar/large molecules use to enter a cell?
Active transport
What type of proteins enable passage of molecules that cannot pass?
Transport proteins
Where are transport proteins?
Embedded in lipid bilayer
What proteins form a hydrophilic open corridor that only certain polar ions can use to get into the membrane?
Channel proteins
Any molecules simply diffusing are moving against/with the concentration gradient?
With; moves DOWN the conc grad
The diffusion of free water across a selectively permeable membrane
Osmosis
When surrounding a certain cell, will cause the cell to lose water
Hypertonic surroundings
When surrounding a certain cell, will cause the cell to gain water
Hypotonic surroundings
The passage of molecules/ions down their electrochemical gradient with the assistance of specific transmembrane ptein
Facilitated diffusion
Na+ VG channels are examples of what type of protein?
Channel proteins
Pumping a solute across a membrane against its gradient takes a lot of energy in a process called
Active Transport
A pump that transports sodium out and potassium into the cell AGAINST their gradients
Sodium potassium pump
Na+/k+ pump pumps __ K into or out of?
2 K into
Na+/K+ pumps __ Na into or out of?
3 Na out of
Is the inside of the cell more positive or negative?
Negative
The voltage across a whole membrane is called
Membrane potential
The diffusion of free water across a selectively permeable membrane, _______________, which actively transports protons (hydrogen ions, ) out of the cell
Proton pump (H+)
