16 Questions
What is a common property of lipids?
Being relatively insoluble in water
What is the primary function of fat in the human body?
To store excess energy
What is the name of the C18 saturated fatty acid?
Octadecanoic acid
What does the notation 18:0 denote in a fatty acid?
A C18 fatty acid with no double bonds
What is the function of lipoproteins in the body?
To transport lipids in the blood
How do nonpolar lipids act in myelinated nerves?
As electrical insulators
What is the typical location of the double bond in most monounsaturated fatty acids?
Between C-9 and C-10
What is the estimated survival time in case of starvation for a 70 kg man?
3 months
What is unique about the double bonds in polyunsaturated fatty acids?
They are always separated by a methylene group
What is the length of hydrocarbon chains in fatty acids?
C4 to C36
What is the common chain length of fatty acids?
Even numbers of carbon atoms in an unbranched chain of 12 to 24 carbons
What type of fatty acids are liquid at room temperature?
Cis-unsaturated fatty acids
What is the name of the C16 fatty acid?
Hexadecanoic acid
What is the name of the fatty acid with the notation 16:0?
Palmitic acid
What is the purpose of partial hydrogenation of fats and oils?
To create trans-unsaturated fatty acids
What is the characteristic of trans-unsaturated fatty acids?
They are produced by microorganisms in the gastrointestinal tract
Study Notes
Lipid Structure and Function
- Lipids are a diverse group of compounds, including fats, oils, steroids, waxes, and related compounds.
- They are relatively insoluble in water and soluble in nonpolar solvents such as ether and chloroform.
Biological Functions
- Lipids are important dietary constituents due to their high energy value.
- Fat-soluble vitamins and essential fatty acids in natural foods are vital.
- Fat is stored in adipose tissue, serving as a thermal insulator in subcutaneous tissues and around organs.
- Nonpolar lipids act as electrical insulators, allowing rapid propagation of depolarization waves along myelinated nerves.
- Lipoproteins are important cellular constituents, serving as the means of transporting lipids in the blood.
Fatty Acids
- Fatty acids are hydrocarbon chains of various lengths (C4 to C36) and degrees of unsaturation, terminating with carboxylic acid groups.
- Systematic names for fatty acids are derived from the parent hydrocarbon by substituting "oic" for the final.
- Fatty acid notation (e.g., 18:0 or 18:2) indicates the carbon chain length and number of double bonds.
Fatty Acid Structures
- Most commonly occurring fatty acids have even numbers of carbon atoms in an unbranched chain of 12 to 24 carbons.
- Double bonds in monounsaturated fatty acids are typically between C-9 and C-10 (Δ9), and in polyunsaturated fatty acids, generally Δ12 and Δ15.
- Double bonds in polyunsaturated fatty acids are separated by a methylene group (-CH=CH-CH2-CH=CH-).
Examples of Fatty Acids
- Palmitic acid (16:0)
- Oleic acid (18:1)
- Linoleic acid (18:2)
- α-Linolenic acid (18:3)
- Arachidonic acid (20:4)
- Lignoceric acid (24:0)
- Nervonic acid (24:1)
Other Fatty Acid Notes
- Essential fatty acids are precursors of prostaglandins.
- Fatty acids with chain lengths of 4-10 carbons are found in significant quantities in milk.
- Trans-unsaturated fatty acids are formed by microorganisms in the gastrointestinal tract of ruminant mammals or through chemical partial hydrogenation of fats and oils.
This quiz covers the chemical structure and diverse biological functions of lipids, including their properties and importance in the diet.
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