T11-12 Lipid Digestion and Absorption Flashcards
A single alcohol functional group can form how many hydrogen bonds?
2
An un-ionized carboxyl group forms how many hydrogen bonds?
3
Is glucose hydrophobic or hydrophilic?
hydrophilic, because of its many -OH groups
Which three classes of molecules are considered to be amphipathic?
fatty acids; phospholipids; cholesterol
Which two classes of molecules are considered to be hydrophobic?
triglycerides; cholesteryl esters
Describe the solubility of fatty acids in water.
low, but finite, solubility in water
How are fatty acids transported in blood? (2)
transported as part of a triglyceride (glycerol backbone + 3 fatty acids); or attached to albumin
Describe the solubility of cholesterol in water.
no solubility in water — it exists at the aqueous/lipid interface
Do most fatty acids have an even or odd number of carbons?
most have an even number of carbons
List the four major groupings of fatty acids and the associated criteria.
short chain (<6 carbons)
medium chain (6-12 carbons)
long chain (13-21 carbons)
very long chain (>20 carbons)
Differentiate between saturated, monounsaturated, and polyunsaturated fatty acids.
saturated = 0 double bonds
monounsaturated = 1 double
polyunsaturated = more than 1 double bond
What are the most common long-chain fatty acids in the human diet?
stearic acid (C18:0)
oleic acid (C18:1)
linoleic acid (C18:2), both double bonds in cis configuation
Why are free fatty acids dangerous? What is a consequence of this property?
they are soaps/detergents that can destroy biological membranes
therefore, FFAs have to be stored as triacylglycerol
Which molecule is the major energy source for all eukaryotes?
triacylglycerol
Describe the hydrophilicity/hydrophobicity of triacylglycerol.
Triacylglycerol is very hydrophobic
In adipose tissue, how are triacylglycerols stored?
stored into one large lipid droplet
How much triglyceride is consumed by the typical American each day?
50-100 grams per day, with 50% from plants and 50% from animals
Describe the relationship between fatty acid saturation and phase of matter.
more saturation (i.e. more C-H bonds and fewer C=C double bonds) means the fat will be more solid at room temperature
Why are plant fats more liquid and animal fats more solid at room temperature?
plant fats = higher proportion of 18:1 and 18:2 unsaturated fatty acids
animal fats = higher 16:0, 18:0 saturated fatty acids
What is an exception to the general trend that plant fats are liquid at room temperature?
tropical plant fats (coconut oil or palm oil) have larger proportions of saturated long-chain fatty acids, so they are more solid at room temperature
What are the major dietary plant sterols? (2)
sitosterol
campesterol
Describe the cholesterol content of meat.
1.4 mg cholesterol per gram
Describe the cholesterol content of egg yolks.
250 mg (surprisingly high)

