Lipids part 2 Flashcards
Semi-permeable structure that defines the boundaries of all cell types
a double layer of
lipids, which acts as a barrier to the passage of polar molecules and ions.
Cell membrane
The cell membrane has many roles:
1. Controlling the flow of ions into and out of the cells
2. Uptake of nutrients and disposal of waste
3. Cell recognition and communication
The fluid Mosaic model which includes lipids, proteins, and carbohydrates allows ___
lateral diffusion
Two types of backbones in membranes which are linked to fatty acids:
Glycerol - simple 3 carbon tri-alcohol
Sphingosine - more complex hydrocarbon (two alcohols, amine, long-chain alkene)
Glycerophospholipids are also known as:
phosphoglycerides
Unsaturated fatty acids are commonly found connected to C2 of glycerol-3-phosphate
The major component of most eukaryotic cell membranes.
Phosphatidylcholine
Type of Ether Lipid
Vinyl ether analog of phosphatidylethanolamine
* Common in vertebrate heart tissue
* Also found in some protozoa and anaerobic bacteria
Plasmalogen
Type of Ether Lipid
Aliphatic ether analog of phosphatidylcholine
Acetic acid has esterified
First signaling lipid
Stimulates aggregation of blood platelets
Plays role in mediation of inflammation
Platelets-Activating Factor
T or F: The backbone of sphingolipids is glycerol
False, the backbone is the amino alcohol sphingosine
Subclasses of sphingolipids (3)
Sphingomyelins
Glycosphingolipids
Gangliosides
Ceramide (sphingosine + amide-linked fatty acid) + phosphocholine attached to the alcohol
is abundant in myelin sheath that surrounds some nerve cells in animals.
Sphingomyelins
Contains both a fatty acid and carbohydrate
contains a single monosaccharide unit - either glucose or galactose
– They occur primarily in brain (7% of dry mass)
Two types:
globosides
gangliosides
Glycosphingolipids
glycosphingolipids with two or more sugars usually D- glucose, D-galactose, or N-acetyl-D-galactosamine
globosides
Most complex glycosphingolipids
contains an oligosaccharide head group with one or more residues of the charged monosaccharide, sialic acid.
Sialic acid gives gangliosides a negative charge at neutral pH.
Gangliosides
Blood groups are determined by the ___ in glycosphingolipids.
type of sugars located on the head groups
Individuals with no active glycosyltransferase will have the ___.
Individuals with a glycosyltransferase that transfers an N-acetylgalactosamine group have ___.
Individuals with a glycosyltransferase that transfers a galactose group have ___.
O antigen
A blood group
B blood group
a lipid whose structure is based on a fused ring system of three 6
carbon rings and one 5 carbon ring
Steroid
The most abundant animal steroid. Related sterols are present in the membranes of most eukaryotic cells.
- modulate fluidity and permeability (stabilizes membranes)
- thicken the plasma membrane
- no sterols in most bacteria
Cholesterol
Important features of biological membranes (4)
Membrane fluidity
Selective permeability
Self-sealing capability
Assymmetry
fluidity of biological membranes is determined by the proportions of saturated and unsaturated fatty acid groups
Cholesterol is able to fit in between the fatty acid side chains of the lipid bilayer.
Membrane fluidity
Each membrane exhibits its own transport capability or selectivity based on its protein component.
Selective permeability
When lipid bilayers are disrupted, they immediately and spontaneously reseal.
Self-sealing capability
Biological membranes are asymmetric, that is, the lipid composition of each half of a bilayer is different.
Assymmetry
A substance moves across a cell membrane by diffusion from a region of higher concentration.
Passive transport
A substance moves across a cell membrane with the aid of a membrane protein.
Facilitated transport
