The Lipid Bilayer

Question 1

Plasma Membrane

Answer 1

Consists of lipid bilayer with embedded proteins

Defines a cell and establishes ion gradients between cytosol & extracellular environment

Defines individual organelles

Contains proteins that are sensors of external signals -> allowing cell to adapt to changing environment

Question 2

Lipids in cell membranes

Answer 2

Most abundant (häufigste) lipids are PHOSPHOLIPIDS
In addition, membranes contain cholesterol & glycolipids
(Lipid is asymmetric-important for cell function)

Lipids in membrane are AMPHIPHILIC (sowohl hydrophil als auch lipophil / in polaren & unpolaren lösungsmitteln gut löslich)

Question 3

Lipid bilayer fluidity

Answer 3

Depends on its composition (phospholipids & cholesterol)

Depends on fatty acid hydrocarbon chain length & double bonds:
SHORT CHAINS & DOUBLE BOND INCREASE FLUIDITY

Cholesterol increases fluidity & provides mechanical STABILITY

Question 4

Phospholipid distribution (lipid bilayer is asymetric)

Answer 4

OUTER MONOLAYER: Phosphatidylcholine & sphingomyelin

INNER MONOLAYER: phosphatidylserine & phosphatidylethanolamine

Question 5

Glycolipid distribution (lipid bilayer is asymetric)

Answer 5

OUTER MONOLAYER

Function: protection, cell recognition

Question 6

Cholesterol distirbution (lipid bilayer is asymetric)

Answer 6

Equally in both monolayers