Membranes and Lipids Flashcards
(39 cards)
Which membrane type consists of the greatest percentage of cell membranes in a cell in liver hepatocytes or liver exocrine cells
rER
Plasma is only 2%/5%
Does the plasma membrane consist a majority of a cell’s membrane content?
no lol
What is a membrane lipid bilayer permeable/impermeable to
permeable to:
- Small Hydrophobic Molecules (e.g. O2)
- Small Uncharged polar molecules (H2O, Ethanol)
Impermeable to:
- Large uncharged polar molecules (e.g. amino acids, glucose)
- Ions (e.g. H+, Cl-)
Hydrophobic Lipid Bilayer Rough Thickness
5-8nm
Integral Proteins
Membrane Spanning Protein
Peripheral Proteins
Protein attached to Membrane
Layer of associated carbohydrates on membranes
Glycocalyx
How are glycocalyxes attached to membranes
Via glycoproteins or glycolipids
Nature of all membrane lipids (in terms of attraction to water)
Amphipathic
Micelles
The formation of a spherical monolayer by membrane lipids
Saturated Fatty Acids
No Double Bonds
Two Main Types of Lipids in Membranes
Phospholipid
- Contains phosphate group in hydrophilic part
Glycolipid
- Contains covalently attached carbohydrate
How are phospholipids joined
Via a phosphodiester linkage
3 Classes of Membrane Lipids
- Phosphoglycerides (Phospholipid)
- Sphingolipids (Phospho- or Glyco- Lipid)
- Cholesterol (Sterol)
Describe the vague structure of a phosphoglyceride
Fatty acids Esterified to glycerol backbone
Phosphate attached to position 3 of glycerol
Phosphate head is hydrophilic
How do phosphoglycerides vary
The hydrophilic head groups generally differentiate them
Most prominently occurring phosphoglyceride
Phosphatidylcholine
**Lecithin
Sphingolipids
A simple fatty acid joined to sphingosine (Fatty Amine)
Can be phosholipid or glycolipid
Has 2 Hydrophobic tails; one fatty acid residue (R) and one from fatty acid tail
Where are sphingolipids found
Often prominent in neuron membranes
**Sphingomyelin found in myelin sheaths
Purpose of sphingolipids
Not really known
What percentage of membranes does cholesterol account for
Around 10%
Why is vegan diet cholesterol free
Plant membranes use phytosterols not cholesterol
How does cholesterol maintain fluidity
Ring structure is very rigid so the fatty acids that it attracts are held but other parts are not held and this promotes fluidity
What is more prominent in outer membrane leaflet
Phosphatidylcholine and Sphingomyelin
**DONT MEMORISE
