Lipids Flashcards
Steroids
Ringed lipids that help regulate metabolic activities.
Examples: cholesterol, steroid hormones, vitamins
Steroids
Fat-soluble vitamins
The four fat-soluble vitamins are A, D, E, K.
Mnemonic: Think of a FAT NAKED man on the beach.
Steroids
Cholesterol
Plays two key roles:
1) Structure and fluidity in the cell membrane
2) Precursor to steroid hormones
Steroids
Steroid hormones
Key properties of steroid hormones:
1) They act more slowly because their mechanism affects gene transcription and expression.
2) They have a long half-life so they work at low concentrations.
3) They can diffuse freely but act only on cells with their specific high-affinity receptor.
Steroids
Terpenes
These are precursors of steroids that are non-cyclic and contain double bonds. They form into steroids through a cyclization reaction.
Lipid Storage
Adipocytes
Cells that store lipids inside their smooth endoplasmic reticulum.
Also known as lipocytes or fat cells.
Lipid Storage
Micelle
In aqueous solutions, phospholipids will form into a micelle, due to the grouping together of hydrophobic components.
The hydrophobic tails will point inward and the hydrophilic heads will point outward.
Lipid Storage
Chylomicrons
These are lipoproteins that function in transport of triacylglycerols. They are similar structurally to a micelle but also contain proteins.
Lipid Storage
Saponification reaction
Refers to the ester hydrolysis of triacylglycerols, with the nucleophilic attack performed by a strong base.
This results in free fatty acids which travel in the bloodstream.
Lipid Storage
Soaps
Salt forms of free fatty acids
Types of lipids
Waxes
Contain long-chain alcohol esters connected to a fatty acid.
Provide waterproofing and defense. Mainly present in plants.
Types of lipids
Phospholipids
Form the membrane bilayer. Contain a polar head and a nonpolar tail.
Types of lipids
Sphingolipids
A lipid with a sphingosine backbone.
Most are phospholipids and are found in the cell membrane.
Glycosphingolipids are attached to a sugar rather than a phosphate.
Types of lipids
Lipid rafts
Regions of the cell membrane with glycoprotein, cholesterol, and receptors organized into a unit.
The lipid component allows the unit to move around the membrane.
Types of lipids
Triacylglycerols
A form of fatty acids that functions as energy storage.
Composed of a glycerol backbone attached to three fatty acids.
Properties of lipids
Saponification
The ester hydrolysis of lipids using a strong base.
Phospholipid structure
Overall structure
Structurally they are like a triacylglycerol, but one of the fatty acids is replaced by a phosphate.
Phospholipid structure
Head
The head consists of a phosphate group connected to an alcohol and is polar.
Phospholipid structure
Tail
The tail consists of two fatty acids and is nonpolar.
Phospholipid structure
Head-tail linkage
The head and tail are connected by a phosphodiester linkage
Phospholipid structure
Backbone
The backbone is made of glycerol (glycerophospholipid) or sphingosine (sphingophospholipid).
