30 Questions
Which type of lipids contain phosphate in addition to fatty acids and alcohol?
Compound lipids
Where are fatty acids mainly found in natural fats?
As unesterified form
What is the term for fatty acids containing no double bonds?
Saturated
What does the term 'ω9' indicate in relation to a fatty acid chain?
A double bond on the ninth carbon
Which carbon is referred to as the omega carbon in fatty acids?
Terminal methyl group
In which lipids can derived lipids be found in association with nature?
Compound lipids
What is phosphatidylglycerol formed from?
Phosphatidic acid and glycerol
How many glycerol molecules are present in cardiolipins?
2
What makes plasmalogens different from other phospholipids?
Enol form of fatty alcohol
Where are cardiolipins found in the human body?
Nervous system
How many phosphates are present in diphosphatidylglycerol?
2
What characterizes the R group in plasmalogens?
Choline
What is the precursor of the ω6 family of polyenoic acids?
Linoleic acid
Which acids are present in nuts, olives, and various oils such as sunflower, cottonseed, and corn oil?
ω6 PUFAs
What physical properties dictate that fatty acids containing up to six carbons are completely soluble in water?
Solubility in lipids
Which fatty acids are considered essential and not synthesized in our body?
Linoleic acid
Which fatty acids are classified as non-essential and are formed in our body mainly from carbohydrates?
Stearic acid
What beneficial health effects do ω3 PUFAs provide?
Lower the blood pressure
Where are phytosterols primarily found?
Higher plants
Which organ can synthesize its own cholesterol?
Liver
What form does free cholesterol take?
Nonesterified
Where is cholesterol found in the highest concentrations?
Adrenals
What can cholesterol be converted into in the liver?
Bile acids
What is cholesterol's main role in cell membranes?
Structural component
What is the structure of gangliosides composed of?
Ceramide and a complex carbohydrate radical
Where are glycolipids mainly found in the body according to the text?
Brain tissues and myelin sheath
What is the main function of gangliosides in cell membranes?
Act as receptors for hormones and external stimuli
Which lipids are produced by the hydrolysis of either simple or conjugated lipids according to the text?
Steroids
How many carbon atoms are present in the steroid nucleus as described in the text?
17
What is the classification of steroids discussed in the text?
Sterols, bile acids, and steroid hormones
Study Notes
Biomedical Intake
- Decreased plasma cholesterol and polyenoic acids
- ω6 PUFAs (e.g., linoleic acid) and ω3 PUFAs (e.g., α-linolenic acid) are present in nuts, oils, flaxseed, canola, and fish oil
- Intake of ω6 PUFAs may lead to decreased plasma cholesterol
- Intake of ω3 PUFAs may reduce the incidence of cardiovascular disease by:
- Lowering blood pressure
- Lowering plasma triacylglycerol levels
- Decreasing the tendency to thrombosis
Nutritional Classification of Fatty Acids
- Essential Fatty Acids (EFAs):
- Not synthesized in the body, must be taken in through diet
- Include α-linolenic and linoleic acids
- Deficiency produces: dermatitis in infants, fatty liver, growth retardation, defective sperms, brain, and retina
- Non-Essential Fatty Acids:
- Formed in the body from carbohydrates
- Not essential to take in through diet
Physical Properties of Fatty Acids
- Solubility in water:
- Fatty acids with up to six carbons are completely soluble in water
- Waxes: esters of fatty acids with higher molecular weight monohydric alcohols
- Compound lipids:
- Phospholipids: contain phosphate in addition to fatty acids and alcohol
- Glycolipids (glycosphingolipids): contain a fatty acid, sphingosine, and carbohydrate
Fatty Acids
- Occur mainly as esters in natural fats and oils
- Fatty acids that occur in natural fats are usually monocarboxylic acids containing an even number of carbon atoms
- Chain may be saturated (no double bonds) or unsaturated (one or more double bonds)
Nomenclature of Fatty Acids
- Carbon atoms are numbered from the carboxyl carbon (carbon No. 1)
- The carbon atoms adjacent to the carboxyl carbon are numbered as 2, 3…etc and are also known as α, β…etc, carbons respectively
- The terminal methyl group is known as the ω carbon, used to indicate the site of a double bond
Phosphatidylglycerol
- Formed from phosphatidic acid and glycerol
Cardiolipins (Diphosphatidylglycerol)
- Formed from two molecules of phosphatidic acid connected by a molecule of glycerol
- Contain 4 FAs, 3 glycerol, and 2 phosphates
- Important component of inner mitochondrial membrane
Plasmalogens
- Type of ether phospholipid
- Characterized by the presence of an enol form of fatty alcohol in ether linkage at position-1, a fatty acid at position-2, and an R-group at position-3
- Found in numerous human tissues (e.g., nervous and cardiovascular system)
Sterols
- Include zoosterols (animals and humans), phytosterols (higher plants), and mycosterols (lower plants, yeast, and fungi)
- Cholesterol:
- Exogenous (dietary) sources: eggyolk, red meat, liver, kidney, butter, and brain
- Endogenous: synthesized by the liver and intestine
- Present in all tissues, but higher concentrations in nervous tissue, liver, adrenals, gonads, skin, and adipose tissue
- Plasma level: 120-200 mg/dL (30% free, 70% esterified)
- Importance and derivatives of cholesterol:
- Converted into bile acids and bile salts in the liver
- Precursor of all steroid hormones
- Can be oxidized into 7-dehydrocholesterol, then converted into vitamin D3 under UV rays
- Important constituent of cell membranes
This quiz covers the classification of lipids, including waxes, compound lipids (such as phospholipids and glycolipids), and derived lipids. Test your knowledge on the different types of lipids and their components.
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