Topic 1 Lipids Flashcards
- Contain carbon, hydrogen, and oxygen atoms (CHO), like carbohydrates
- Have long hydrocarbon tails that make them very hydrophobic
Lipid
- Lipid molecule with a glycerol backbone and three fatty acids
- Glycerol and the three fatty acids are connected by ester linkages
- Saturated: no double bonds, straight chains, bad for health
- Unsaturated: double bonds, kinks, good for health
Triacylglycerol (triglyceride)
- Three carbons and three hydroxyl groups
Glycerol backbone
- Long hydrocarbon tails
Fatty acids
- Have no double bonds and as a result pack tightly (solid at room temperature)
Saturated fatty acids
- Have double bonds
- Can be divided into monounsaturated fatty acids and polyunsaturated fatty acids
Unsaturated fatty acids
- One double bond
Monounsaturated fatty acids
- Two or more double bonds
Polyunsaturated fatty acids
- Have kinks that cause the hydrocarbon tails to bend
- Do not pack tightly
Cis-unsaturated fatty acids
- have straighter hydrocarbon tails
- pack tightly
Trans-unsaturated fatty acids
Phospholipids, Cholesterol, and Steroids
Lipid Molecules
- lipid molecules that have a glycerol backbone, one phosphate group, and two fatty acid tails
- the phosphate group is polar
- the fatty acids are nonpolar
- amphipathic
- assemble to form lipid bilayers
Phospholipids
- lipid molecule that is a component of the cell membranes and is amphipathic
- the most common precursor to steroid hormones
- the starting material for vitamin D and bile acids
Cholesterol
- 3 6-membered rings and 1 five-membered ring
Steroids
- both hydrophobic and hydrophilic
Amphipathic
- lipids that have four hydrocarbon rings
Steroid Hormones
Temperature, Cholesterol, Degrees of unsaturation
Factors that influence membrane fluidity
- Increasing temperatures increase fluidity while decreasing temperatures decrease it
- Become rigid in cold water
- Become flexible in warm water
Temperature
- Holds membrane together at high temperatures and keeps membrane fluid at low temperatures
Cholesterol
- Saturated fatty acids pack more tightly that unsaturated fatty acids, which have double bonds that may introduce kinks
Degrees of unsaturation
- Allow the transport of lipid molecules in the bloodstream due to an outer coat of phospholipids, cholesterol, and proteins
Lipoproteins
- Low-density lipoproteins (LDLs)
2. High-density lipoproteins (HDLs)
Types of Lipoproteins
- Have low protein density
- Work to deliver cholesterol to peripheral tissues
- Sometimes considered “bad cholesterol” which can cause vessel blockage and heart disease
Low-density lipoproteins (LDLs)
- Have high protein density
- Take cholesterol away from peripheral tissues
- Considered “good cholesterol” because they deliver cholesterol to the liver to make bile (reduces blood lipid levels)
High-density lipoproteins (HDLs)
- Simple lipids with long fatty acid chains connected to monohydroxy alcohol through ester linkages
- Used mainly as protective coatings on skin and exoskeleton
Waxes
- Contain a single hydroxyl group
Monohydroxy alcohols
- Lipid derivatives containing long fatty acid carbon chains with conjugated double bonds and six-membered rings at each end
- Function mainly as pigments
- Subgroups: carotenes and xanthophylls
Carotenoids
- Have a backbone with alipathic (non-aromatic) amino acids
- Serve important functions in the plasma membranes of cells
Sphingolipids
- 4 joined pyrrole rings
Porphyrins
- Specialized fat cells
- Two types:
1. White fat cells
2. Brown fat cells
Adipocytes
- composed of triglycerides with a thin layer of cytoplasm
White fat cells
- have cytoplasm, lipid droplets, and mitochondria
Brown fat cells
- Carbohydrate group instead of phosphate group like phospholipids
Glycolipids
- Transport lipids in the blood
- Lipid cores surrounded by phospholipids and apolipoproteins
Lipoproteins
