30 Questions
What is the Greek origin of the term 'lipids'?
Lipos means 'fat'
Which of the following is NOT a function of lipids in the body?
Forming the backbone of proteins
What makes fats different from oils?
Fats are solid at room temperature, while oils are liquid
Which type of simple lipids are esters formed from long-chain carboxylic acids and long-chain alcohols?
Waxes
What is the composition of fats like triacylglycerides?
Glycerol backbone with 3 esterified fatty acids
What characterizes compound lipids?
Esters of fatty acids with alcohol and additional group
What is the meaning of the Greek word 'eikos'?
20
Which compound is responsible for inducing contraction of the muscle in airways to the lungs?
Leukotrienes
What effect do prostacyclins have on blood vessels?
Dilating blood vessels
Which compound is involved in regulating inflammation, blood pressure, and fever?
Prostaglandins
What is the main mechanism of action for Paracetamol and Aspirin as described in the text?
Inhibit prostaglandin synthesis
Which enzymatic pathways lead to the synthesis of eicosanoids?
Cyclooxygenase and lipoxygenase
Which type of cholesterol is known as the 'good' cholesterol?
HDL
What is the function of LDL particles in the bloodstream?
Transport cholesterol from the liver to other tissues
How many types of lipoprotein particles are classified based on their density?
5
Why do some doctors recommend aspirin to reduce the chance of heart attack or stroke?
To decrease blood clotting
What is the purpose of a lipid profile test?
To screen for risk of cardiovascular disease
Which lipoprotein is responsible for removing cholesterol from cell surfaces?
HDL
Why are omega-3 and omega-6 fatty acids considered essential?
Because they cannot be synthesized by the body
What causes rancidity in oils and fats?
Exposure to air and moisture
Which type of fatty acids are particularly susceptible to oxidative rancidity?
Polyunsaturated fatty acids
What is the role of eicosanoids in the body?
Function as hormones
What causes the unpleasant taste and smell associated with rancidity?
Formation of butyric acid
Why are fatty acids like omega-3 and omega-6 important for human health?
To synthesize eicosanoids
What effect do unsaturated fatty acids have on their melting points compared to saturated fatty acids?
They have lower melting points
How does the number of double bonds in unsaturated fatty acids affect their melting points?
The melting points decrease as the number of double bonds increases
Why are linoleic acid and α-linolenic acid considered essential fatty acids?
Because they cannot be synthesized in the body beyond certain unsaturation sites
How are linoleic acid and α-linolenic acid obtained by humans?
By consuming a variety of plants or animals that have consumed these plant fats
What is the significance of linoleic and α-linolenic acid being referred to as omega fatty acids?
They have unsaturation sites beyond certain carbons
What is the main reason that linoleic and α-linolenic acid cannot be synthesized in the body?
Due to the specific location of their unsaturation sites
Study Notes
Lipids
- Lipids are organic compounds found in living organisms that are soluble in nonpolar organic solvents.
- Lipids have a variety of structures and functions, including fats, oils, waxes, cholesterol, other sterols, and most steroids.
Functions of Fat in the Body
- Makes food palatable
- Provides energy
- Acts as a thermal insulator and cushion around organs
- Stores fat-soluble vitamins (A, D, E, etc.)
- Forms the backbone of hormones and cell membranes
Classification of Lipids
- Lipids can be classified into three types: simple lipids, compound lipids, and derived lipids
Simple Lipids
- Esters of fatty acids with various alcohols
- Examples include:
- Fats: Esters of fatty acids with glycerol (e.g., triacylglycerides)
- Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols (e.g., beeswax)
Compound Lipids
- Esters of fatty acids with alcohol and possessing additional groups
Essential Fatty Acids
- Two essential fatty acids that cannot be synthesized by the body: linoleic acid and α-linolenic acid
- These fatty acids must be obtained through diet or by consuming plants or animals that have consumed these plant fats
Omega Fatty Acids
- Omega-3 (ω3) and omega-6 (ω6) fatty acids are unsaturated essential fatty acids
- Examples include:
- Palmitoleic acid (16:1Δ9)
- Stearic acid (18:0)
- Oleic acid (18:1Δ9)
- Linoleic acid (18:2Δ9,12)
- α-Linolenic acid (18:3Δ9,12,15)
- Arachidonic acid (20:4Δ5,8,11,14)
- Eicosapentaenoic acid (20:5Δ5,8,11,14,17)
Rancidity of Oils
- Rancidity is a degradation process that modifies lipids, resulting in an unpleasant taste and smell
- Caused by incomplete oxidation or hydrolysis of fats and oils, or by bacterial action
Eicosanoids
- Hormones synthesized from essential fatty acids omega-3 and omega-6
- Examples include:
- Prostaglandins: regulate physiological responses such as inflammation, blood pressure, blood clotting, fever, and pain
- Thromboxanes: constrict blood vessels and stimulate platelet aggregation
- Leukotrienes: induce contraction of airway muscles and implicated in allergic reactions, inflammatory reactions, and heart attacks
- Prostacyclins: dilate blood vessels and inhibit platelet aggregation
Mechanism of Analgesic
- Aspirin and paracetamol are weak inhibitors of cyclooxygenase-1 (COX-1) and COX-2
- Inhibit thromboxane synthesis and prostacyclin production, leading to decreased blood clotting and anti-inflammatory effects
Lipoproteins and Lipid Profile
- Lipoproteins are particles that contain cholesterol, cholesterol esters, phospholipids, and proteins
- Classified into five types based on density: high-density lipoprotein (HDL), intermediate lipoprotein (IDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and chylomicrons
- HDL is a cholesterol scavenger, removing cholesterol from membranes and delivering it back to the liver
- LDL is the "bad" cholesterol, while HDL is the "good" cholesterol
Test your knowledge about omega-3 and omega-6 essential fatty acids, their common names, structures, and roles in the diet. Learn about the numerical symbols and common names of various fatty acids along with the concept of rancidity in oils.
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