2.4-2.5 Plasma membrane And Plant Cells Flashcards
What does the plasma membrane separate?
Separate internal cell environment (intracellular space) from external environment (extracellular space)
What is the Plasma membrane comprised primary of?
Phospholipids
Phospholipids are amphipathic because? What do they form? (2)
- Hydrophilic heads and hydrophobic tails (has both properties)
- forms a bilayer
The plasma membrane is selectively permeable. What does that mean?
- The ability of a membrane to regulate the substances that enter and exit
Where are the hydrophilic heads oriented?
Towards the aqueous environment
Where are the hydrophobic tails oriented?
Facing inward away from aqueous environment
What is the Fluid Mosaic Model?
A model to describe the structure of cell membranes
The fluid membrane is held together by what type of interactions, and what does it allow? (2)
- how together by weak hydrophobic interactions and can therefore move and shift
What factors affect fluidity of the cell membrane? (3)
- temperature
- unsaturated hydrocarbon tails help maintain fluidity at low temps
— because kinked tails prevent tight packing of phospholipids
How does cholesterol help maintain fluidity of the cell membrane? (3)
- maintains fluidity at high and low temps
- high temperature: reduces movement
- low temperature: reduced tight packing of phospholipids to prevent breakage at cold temps, and increase rigidity
What does the “Mosaic” mean in the fluid mosaic model?
The plasma membrane is comprised of many macromolecules
What are the two major categories of proteins in the plasma membrane?
Integral and peripheral proteins
What are integral proteins? (3)
- proteins that are embedded into the lipid bilayer
- A.k.a. transmembrane proteins
- Amphipathic
What are peripheral proteins?
- Proteins that are not embedded into the lipid bilayer
- loosely bonded to the surface
What are membrane carbohydrates important for?
Cell-to-cell recognition
