Plasma Membrane Flashcards
Fluid-mosaic Model
- is a description of the plasma membrane
- ‘fluid’ comes from phospholipid bilayer which has consistency like light oil
- ‘mosaic’ comes from integral proteins studded along membrane
Components of the Plasma Membrane & their Functions
1- Phospholipid bilayer
2- Cholesterol (steroid): strength & support to bilayer
3- Actin Filaments: tend to cross each other in a mesh to support the intracellular membrane
4- Peripheral Proteins: work w/actin filaments to support intracellular membrane
5- Integral Proteins: integrated & spans whole width of the membrane
6- Glycoprotein: carb chain + protein
7- Glycolipid: carb chain + phospholipid
Integral Proteins
- span entire width of membrane
- can change position @ anytime
- various functions
- many diff kinds in a cell membrane
- determine cell function
Channel Proteins
Selective, allows molecules/ions to move passively down concentration gradient by diffusion
eg. Hydrogen, Chlorine, ATP
-Cystic Fibrosis
Carrier Protein (passive)
Selective, allows molecules/ions to move through membrane one by one down its concentration gradient by diffusion.
eg. glucose, amino acids
-???
Carrier Protein (active)
Selective, requires energy to pump molecules/ions against their concentration gradient in an unequal swap (to maintain charge).
eg. Sodium-Potassium pump imp. for nerve transmission
-migraine headaches
Cell Recognition Protein
A glycoprotein; the carb chain is linked to DNA & can differentiate if another cell has the same carb chain. If not, it requires energy to trigger immune response.
- MHC Major Histocompatability Complex (glycoproteins)
- organ rejection from transplant
Receptor Protein
“Lock & Key” method; bonds w/correct key to unlock a reaction in the cell (req energy).
Purely a reactive (not transport) cell.
eg. Insulin ‘key’ triggers other passive carrier proteins to wake up & function
-Diabetes
Enzymatic Protein
Catalyzes a specific reaction; acts as an enzyme that synthesizes/breaks down certain molecules.
- Involved in metabolism, breaking down food into monomers to use by the body (ATP)
eg. triglyceride hydrolyzed by body into 1 glycerol + 3 fatty acids
-Cholera
Glycolipids
Lipid in plasma membranes that bears a carb chain attached to hydrophobic tail on the extracellular side
Glycoproteins
Proteins in the plasma membrane that bears a carb chain on the extracellular side
Facilitated Transport
No energy required. Use of a plasma membrane carrier to move a substance into/out of a cell down its concentration gradient.
Active Transport
Energy required. Use of Use of a plasma membrane carrier to move a substance into/out of a cell against its concentration gradient.
-pump
Differentially Permeable
The ability to regulate the passage of substances into/out of the cell.
-factors: size, polar/non-polar
Membrane-Assisted Transport (Vesicle Formation)
Used for large macromolecules to pass through the membrane by forming vesicles around them (req. energy).
- keeps molecules contained
- quarantine from cytoplasm
