5 LIPIDS Flashcards
What are lipids and lipoproteins primarily composed of?
Carbon, hydrogen, and oxygen (CHO)
What additional element is often coupled with CHO in biomolecules to form proteins?
Nitrogen
What biomolecule element combination indicates carbohydrates or lipids?
CHO without nitrogen
What is another common term for lipids?
Fats
What is the main type of bond in lipids that makes them hydrophobic?
Covalent and hydrophobic bonds
In what type of solvents are lipids soluble?
Organic solvents (e.g., chloroform, ether)
What type of transport mechanism is required for lipids in the blood?
Lipoproteins
What role do lipids play in energy storage?
Storing energy
Which vitamins rely on lipids for absorption in the small intestine?
Vitamins A, D, E, and K
What structural role do lipids play in cells?
They are components of the cell membrane.
Name a type of hormone synthesized from lipids.
Steroid hormones (e.g., estrogen, testosterone)
What lipid consists of three fatty acids attached to a glycerol molecule?
Triglycerides (or triacylglycerol)
What lipid has a phosphate group attached?
Phospholipids
What is the structure of cholesterol?
Carbon ring structure with alcohol functional groups
A cholesterol molecule forming an ester bond with another molecule
cholesteryl ester
What group do fatty acids terminate with?
Carboxyl group (-COOH)
How are fatty acids classified based on their length?
Short-chain (4-6 carbons), medium-chain (8-12 carbons), and long-chain (more than 12 carbons)
What distinguishes saturated from unsaturated fatty acids?
Saturated fatty acids have no double bonds, while unsaturated fatty acids contain double bonds.
What type of configuration do cis fatty acids have?
Same side of the molecule
What type of configuration do trans fatty acids have?
Opposite configuration
What is another name for triglycerides?
Neutral fats
How many fatty acids are attached to glycerol in triglycerides?
Three fatty acids
What type of triglycerides tend to be solid at room temperature?
Those containing saturated fatty acids
Where are triglycerides primarily stored in the human body?
Adipose tissue
How do phospholipids differ structurally from triglycerides?
Phospholipids have only two fatty acids.
Where are phospholipids primarily found in the cell?
Cell membrane (phospholipid bilayer)
Which part of the phospholipid bilayer is hydrophilic?
The head
Which part of the phospholipid bilayer is hydrophobic?
The tail
What is the most abundant form of phospholipid in the cell membrane?
Lecithin (phosphatidylcholine) – 70%
Which phospholipid is found in the myelin sheath of neurons?
Sphingomyelin
Name two types of cephalin.
phosphatidyl ethanolamine and phosphatidyl serine
What role does phosphatidyl serine play in cell signaling?
It serves as a cell receptor for signal transduction.
What is the purpose of the hydrophilic heads in the phospholipid bilayer?
To interact with the extracellular matrix and cytoplasm
What purpose does phospholipid testing serve in fetal development?
To assess if the fetus can survive delivery and detect potential fetal distress
What is the backbone of sphingomyelin?
Sphingosine
In which organs does sphingomyelin accumulate in Niemann-Pick disease?
Liver and spleen
Which phospholipid is derived from sphingosine rather than glycerol?
Sphingomyelin
In which cells or tissues is sphingomyelin an essential component?
Red blood cell (RBC) membranes and nerve sheaths
What type of molecule is cholesterol?
An unsaturated steroid alcohol
How many rings does the structure of cholesterol contain?
Four rings (A, B, C, and D)
What are the two forms of cholesterol?
Esterified (cholesteryl ester) and unesterified (free cholesterol)
What condition results from high cholesterol levels in the blood?
Hypercholesterolemia
What role does cholesterol play in steroid hormone synthesis?
It acts as a precursor.
What can cholesterol be converted into in the liver?
Bile acids (e.g., cholic acid, chenodeoxycholic acid)
Name a vitamin that cholesterol can help synthesize.
Vitamin D
What reaction does LCAT catalyze for cholesterol?
Esterification of cholesterol
In which organ is LCAT synthesized?
Liver
What protein activates LCAT?
Apo A-1 (found in HDL)
What happens to HDL when LCAT is activated?
It accumulates cholesterol as cholesterol ester (esterified cholesterol).
What process involves liberating cholesterol from its ester form?
Saponification
What is the function of cholesterol in the body besides being a fuel source?
Precursor for steroid hormones, bile acids, and vitamin D
What shape are lipoproteins?
Spherical
What is located on the surface of lipoproteins?
Cholesterol and phospholipids
What is located in the core of lipoproteins?
Triglyceride and cholesteryl ester
What is the main function of lipoproteins?
Delivery of fuel (lipids) to peripheral cells
Name the four major human lipoproteins.
Chylomicrons, VLDL, LDL, HDL
Which lipoprotein is the least dense?
Chylomicrons
Which lipoprotein is the most dense?
HDL
Which lipoprotein carries exogenous triglycerides?
Chylomicrons
Which lipoprotein carries endogenous triglycerides?
VLDL
What is the role of LDL in cholesterol transport?
Transports cholesterol from the liver to peripheral cells (“bad cholesterol”)
What is the role of HDL in cholesterol transport?
Transports cholesterol from peripheral cells to the liver (“good cholesterol”)
Where are apolipoproteins primarily located?
On the surface of lipoprotein particles
What role do apolipoproteins play in the structural integrity of lipoproteins?
They help maintain structural integrity.
What is the function of apolipoproteins as ligands?
They act as ligands for cell receptors and as activators/inhibitors for enzymes.
How do apolipoproteins aid in lipid solubilization in the blood?
They assist in the esterification of lipids.
Name the enzyme that catalyzes the lysis of lipid bonds in lipoproteins.
Lipoprotein Lipase (LPL)
What is the primary apolipoprotein found in chylomicrons?
Apo B-48
How do chylomicrons affect the appearance of postprandial (after eating) plasma?
They cause turbidity in the plasma.
Where are chylomicrons produced?
In the intestine
What is the principal role of chylomicrons?
Delivery of dietary lipids to hepatic and peripheral cells
What layer do chylomicrons create in plasma?
A creamy top layer
What is the electrophoretic pattern of VLDL?
Pre-beta lipoprotein
Where are VLDL produced?
In the liver
What apolipoproteins do VLDL contain?
Apo B-100, apo E, and Apo Cs
What do VLDL primarily transport?
Endogenous triglycerides from the liver to peripheral tissues
What condition causes VLDL to contribute to turbidity in plasma?
Fasting hyperlipidemia
What is the layman’s term for LDL
Bad cholesterol
What is the electrophoretic pattern of LDL?
Beta lipoprotein
What is the primary apolipoprotein in LDL?
Apo B-100
How is LDL formed
From the lipolysis of VLDL
What risk is associated with elevated levels of LDL
Hypercholesterolemia leading to atherosclerosis
What is the layman’s term for HDL
Good cholesterol
What is the electrophoretic mobility pattern of HDL?
Alpha lipoprotein
What is the size and density of HDL compared to other lipoproteins?
Smallest and most dense lipoprotein particle
Which apolipoprotein is typically found in HDL
Apo A-1
What are the two major types of HDL?
HDL2 and HDL3
What type of lipoprotein is Lipoprotein (a)
LDL-like particle
What does Lipoprotein (a) contain linked to Apo B-100?
One molecule of apo (a)
What is the risk associated with elevated levels of Lipoprotein (a)?
Increased risk of premature coronary heart disease and stroke
How is IDL classified in relation to lipoproteins?
A minor lipoprotein
What is Lipoprotein X (LpX) rich in?
Free cholesterol and phospholipids
In what conditions is LpX found?
Obstructive jaundice and LCAT deficiency
What does Beta-VLDL refer to?
VLDL that appears in the LDL position during electrophoresis
What condition is associated with the accumulation of Beta-VLDL?
Type 3 hyperlipoproteinemia
