BIOCHEMISTRY VIVA QUESTIONS: 100 Q&A IN LIPIDS.
- What are lipids?
Lipids are a group of biomolecules that include fats, oils, waxes, phospholipids, and steroids. They are characterized by their insolubility in water but solubility in organic solvents.
- What are the primary functions of lipids in the body?
Lipids serve several important functions, including energy storage, structural component of cell membranes, insulation, and signaling.
- What are triglycerides?
Triglycerides are the most common type of lipid in the body and dietary fats. They consist of glycerol and three fatty acids.
- How do lipids differ from carbohydrates and proteins in terms of energy storage?
Lipids store more energy per gram (approximately 9 calories) compared to carbohydrates and proteins (approximately 4 calories each).
- What are saturated fatty acids?
Saturated fatty acids have no double bonds between carbon atoms in their hydrocarbon chain and are typically solid at room temperature.
- Give an example of a food high in saturated fats.
Butter is an example of a food high in saturated fats.
- What are unsaturated fatty acids?
Unsaturated fatty acids have one or more double bonds in their hydrocarbon chain and are usually liquid at room temperature.
- Name two types of unsaturated fatty acids.
Two types of unsaturated fatty acids are monounsaturated and polyunsaturated.
- Which fatty acid is commonly found in olive oil?
Oleic acid is a monounsaturated fatty acid commonly found in olive oil.
- What is the difference between cis and trans fatty acids?
Cis fatty acids have the hydrogen atoms on the same side of the double bond, while trans fatty acids have the hydrogen atoms on opposite sides.
- Are trans fats healthy?
No, trans fats are considered unhealthy and are associated with an increased risk of heart disease.
- What are essential fatty acids?
Essential fatty acids are fats that the body cannot produce, so they must be obtained from the diet. Examples include omega-3 and omega-6 fatty acids.
- How are essential fatty acids beneficial to health?
Essential fatty acids play crucial roles in brain function, cell membranes, and inflammation regulation.
- What are phospholipids?
Phospholipids are a type of lipid that forms the structural basis of cell membranes. They have a hydrophilic head and hydrophobic tail.
- What is the role of cholesterol in the body?
Cholesterol is a lipid that is vital for cell membrane structure, hormone synthesis, and bile acid production.
- Where is cholesterol produced in the body?
Cholesterol is primarily synthesized in the liver.
- How is cholesterol transported in the bloodstream?
Cholesterol is transported in the bloodstream by lipoproteins, such as low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
- Which lipoprotein is often referred to as “bad cholesterol”?
Low-density lipoprotein (LDL) is often referred to as “bad cholesterol” because high levels of LDL are associated with an increased risk of heart disease.
- Which lipoprotein is often referred to as “good cholesterol”?
High-density lipoprotein (HDL) is often referred to as “good cholesterol” because it helps remove cholesterol from the bloodstream.
- What is a lipid bilayer?
A lipid bilayer is a double layer of phospholipids that forms the basic structure of cell membranes.
- How does the lipid bilayer provide selective permeability to cell membranes?
The lipid bilayer’s hydrophobic interior prevents the passage of hydrophilic molecules, providing selective permeability.
- What are lipoproteins made of?
Lipoproteins consist of lipids (such as cholesterol and triglycerides) surrounded by proteins.
- What is lipolysis?
Lipolysis is the breakdown of triglycerides into glycerol and fatty acids, releasing stored energy.
- Where does lipolysis primarily occur?
Lipolysis primarily occurs in adipose tissue (fat cells).
- What role do lipids play in vitamin absorption?
Certain vitamins, such as vitamins A, D, E, and K, are fat-soluble, meaning they require lipids for absorption and transport in the body.
- What is the role of lipids in maintaining body temperature?
Lipids, particularly subcutaneous fat, act as insulation and help regulate body temperature.
- What are eicosanoids?
Eicosanoids are lipid signaling molecules that include prostaglandins, thromboxanes, and leukotrienes, which play roles in inflammation and immunity.
- How are lipids transported in the bloodstream after digestion?
After digestion, lipids are transported in the bloodstream as chylomicrons, which are large lipoprotein particles formed in the intestinal cells.
- What is the main function of chylomicrons?
Chylomicrons transport dietary triglycerides and other lipids from the intestines to various tissues in the body.
- What is the difference between endogenous and exogenous lipids?
Endogenous lipids are produced within the body, while exogenous lipids are obtained from the diet.
- How do lipids contribute to cell signaling?
Lipids can act as secondary messengers in various cell signaling pathways, helping to transmit signals within cells.
- What is the role of lipids in myelin sheath formation?
Lipids, particularly sphingomyelin, are essential components of the myelin sheath that insulates and protects nerve cells.
- What is the difference between a fat and an oil?
Fats are lipids that are typically solid at room temperature, while oils are lipids that are liquid at room temperature.
- What is the primary lipid component of cell membranes?
Phospholipids are the primary lipid component of cell membranes.
- What are adipocytes?
Adipocytes are specialized cells that store triglycerides as fat droplets in adipose tissue.
- What is adipose tissue’s primary function?
Adipose tissue serves as the body’s primary energy storage site and acts as a thermal insulator.
- What are lipoprotein lipase and hormone-sensitive lipase?
Lipoprotein lipase is an enzyme that breaks down triglycerides into fatty acids and glycerol, while hormone-sensitive lipase releases stored triglycerides from adipose tissue during lipolysis.
- How are lipids involved in the formation of steroid hormones?
Steroid hormones are derived from cholesterol, a type of lipid.
- What are prostaglandins, and what role do they play in the body?
Prostaglandins are lipid compounds involved in inflammation, blood clotting, and various physiological processes.
- Which lipid compound is a key component of cell signaling pathways?
Diacylglycerol (DAG) is a key lipid component involved in various cell signaling pathways.
- What is the difference between lipids and carbohydrates in terms of energy storage?
Lipids store more energy per unit of weight than carbohydrates.
- What is the function of wax in plants and animals?
Waxes act as protective coatings in plants and animals, preventing water loss and providing a waterproof layer.
- What is a lipid profile test?
A lipid profile test measures cholesterol and triglyceride levels in the blood and helps
assess a person’s risk for cardiovascular disease.
- What are the two main classes of lipids found in the human body?
The two main classes of lipids found in the human body are glycerolipids and sphingolipids.
- What is the role of lipids in cell membrane fluidity?
Unsaturated fatty acids in cell membranes increase fluidity, while saturated fatty acids decrease fluidity.
- How does the body transport cholesterol from the liver to other tissues?
Cholesterol is transported from the liver to other tissues in the body by LDL particles.
- What is the main function of brown adipose tissue (brown fat)?
Brown adipose tissue primarily generates heat by burning fat to help regulate body temperature.
- Which lipid is a precursor for vitamin D synthesis?
Cholesterol is a precursor for vitamin D synthesis when exposed to ultraviolet (UV) radiation from the sun.
- What is the role of lipids in the nervous system?
Lipids play a critical role in neural development and the maintenance of neural function.
- How do lipids contribute to the buoyancy of marine animals?
Certain marine animals store lipids in their tissues, providing buoyancy in water.
- What are the health benefits of omega-3 fatty acids?
Omega-3 fatty acids are associated with reduced inflammation, improved heart health, and cognitive function.
- What is the difference between cis and trans isomers of unsaturated fatty acids in terms of health effects?
Cis isomers of unsaturated fatty acids are generally considered healthier than trans isomers, which are associated with adverse health effects.
- How does excessive consumption of trans fats impact health?
Excessive consumption of trans fats increases the risk of heart disease, stroke, and other cardiovascular problems.
- How can lipids be used as a source of metabolic water?
When triglycerides are broken down during metabolism, water is produced as a byproduct.
- What is the primary function of phospholipids in cell membranes?
Phospholipids form a lipid bilayer, providing a barrier that controls the movement of substances in and out of cells.
- Which lipid is an essential component of bile, aiding in fat digestion?
Bile salts, derived from cholesterol, are essential components of bile.
- What is the main dietary source of phospholipids?
Egg yolks are a primary dietary source of phospholipids, particularly phosphatidylcholine.
- How do lipids contribute to the formation of micelles during digestion?
In the small intestine, bile salts surround dietary lipids, forming micelles that aid in lipid digestion and absorption.
- How do lipids function as surfactants in the lungs?
Lipids, particularly pulmonary surfactant, reduce surface tension in the lungs, preventing alveoli from collapsing during expiration.
- What is the role of lipids in the synthesis of sex hormones?
Lipids, specifically cholesterol, serve as the precursor for the synthesis of sex hormones, such as estrogen and testosterone.
- What is the recommended intake of omega-3 fatty acids per day?
The recommended intake of omega-3 fatty acids varies by age and gender but is typically around 250-500 mg per day for adults.
- How does the body store excess dietary fat?
Excess dietary fat is stored in adipose tissue as triglycerides.
- What is the primary structural component of triglycerides?
The primary structural component of triglycerides is glycerol.
- What is the role of lipids in the myelin sheath’s electrical insulation?
Lipids in the myelin sheath create an electrically insulating layer around nerve fibers, which aids in the rapid conduction of nerve impulses.
- How do lipids contribute to the formation of cell signaling molecules?
Lipids can be cleaved to produce signaling molecules such as eicosanoids, which regulate various physiological processes.
- Which type of lipoprotein transports cholesterol from peripheral tissues back to the liver for excretion?
High-density lipoprotein (HDL) transports cholesterol from peripheral tissues back to the liver for excretion.
- What is the impact of a diet high in saturated fats on blood cholesterol levels?
A diet high in saturated fats can raise LDL cholesterol levels and increase the risk of heart disease.
- Which lipid is the primary storage form of energy in the body?
Triglycerides are the primary storage form of energy in the body.
- How do lipids contribute to the sensation of taste in food?
Lipids, particularly fatty acids, contribute to the sensation of taste in food and can be perceived as “savory” or “umami.”
- What are the health benefits of consuming healthy fats, such as avocados and nuts?
Healthy fats can improve heart health, reduce inflammation, and support brain function.
- How do lipids contribute to the structure and function of cellular organelles?
Lipids form the membrane structures of various cellular organelles, including the endoplasmic reticulum and Golgi apparatus.
- What is the impact of excessive alcohol consumption on lipid metabolism?
Excessive alcohol consumption can lead to abnormal lipid metabolism, contributing to fatty liver disease and other health issues.
- How are lipids involved in the absorption of fat-soluble vitamins in the intestines?
Lipids facilitate the absorption of fat-soluble vitamins (A, D, E, and K) by forming micelles in the small intestine.
- What is the connection between lipids and atherosclerosis?
Elevated levels of LDL cholesterol and low levels of HDL cholesterol are risk factors for atherosclerosis, a condition where plaque builds up in the arteries.
- How do lipids contribute to the energy reserves in hibernating animals?
Hibernating animals rely on stored lipids to sustain themselves during periods of reduced metabolic activity.
- What is the impact of omega-3 fatty acids on cardiovascular health?
Omega-3 fatty acids have been shown to lower blood triglyceride levels and reduce the risk of heart disease.
- How do lipids contribute to the formation of the blood-brain barrier?
Lipids in the cell membranes of brain capillaries create a barrier that regulates the passage of substances between the blood and the brain.
- How are lipids involved in the formation of the outermost layer of the skin?
Lipids in the skin’s outermost layer form a protective barrier that prevents water loss and protects against external factors.
- What is the link between lipids and Alzheimer’s disease?
Abnormal lipid metabolism in the brain has been associated with the development of Alzheimer’s disease.
- How do lipids contribute to energy production during prolonged physical activity?
During prolonged physical activity, the body relies on stored lipids for energy, sparing glycogen stores.
- What is the impact of a high-fat diet on insulin sensitivity?
A high-fat diet can lead to reduced insulin sensitivity and an increased risk of type 2 diabetes.
- How do lipids function as antioxidants in the body?
Some lipids, such as vitamin E, act as antioxidants, neutralizing harmful free radicals.
- What is the role of lipids in the production of sebum on the skin?
Sebaceous glands in the skin produce sebum, a mixture of lipids that helps moisturize and protect the skin.
- How do lipids contribute to the formation of cell signaling receptors?
Lipids play
a role in the structure and function of cell signaling receptors, including G protein-coupled receptors.
- What are the health risks of a diet high in trans fats?
A diet high in trans fats can increase the risk of heart disease, stroke, and inflammation.
- How do lipids contribute to the formation of lipid droplets in cells?
Lipid droplets serve as storage sites for excess lipids in cells, protecting the cell from lipotoxicity.
- What is the link between lipids and obesity?
Excessive consumption of lipids can contribute to obesity, as excess triglycerides are stored as fat in adipose tissue.
- What are the health implications of an imbalance between omega-3 and omega-6 fatty acids?
An imbalance between omega-3 and omega-6 fatty acids may promote inflammation and contribute to various chronic diseases.
- How do lipids contribute to the formation of cell membranes during cell division?
Lipids play a role in the formation of new cell membranes during cell division.
- What is the impact of a low-fat diet on hormone production?
A very low-fat diet can negatively impact the production of certain hormones, including sex hormones.
- How do lipids contribute to the formation of lipid rafts in cell membranes?
Lipid rafts are specific regions of the cell membrane enriched in cholesterol and sphingolipids, contributing to membrane organization and signaling.
- What are the health benefits of consuming omega-3 fatty acids during pregnancy?
Omega-3 fatty acids support the development of the fetal brain and eyes and may reduce the risk of preterm birth.
- How do lipids contribute to the formation of the cuticle in insects and other arthropods?
In insects and other arthropods, lipids contribute to the formation of a waterproof cuticle that protects against water loss.
- What is the connection between lipids and insulin resistance?
Elevated levels of certain lipids can contribute to insulin resistance and the development of type 2 diabetes.
- How are lipids involved in the formation of adipokines in adipose tissue?
Adipokines are hormones and cytokines produced by adipose tissue, and their synthesis may be influenced by the presence of lipids.
- What is the role of lipids in fetal lung development?
Lipids play a critical role in fetal lung development, particularly in the synthesis of pulmonary surfactant.
- How do lipids contribute to the formation of lipid bodies in yeast and other organisms?
Lipid bodies serve as storage sites for lipids in cells, providing a reservoir of energy.
- What are the health implications of consuming too many omega-6 fatty acids compared to omega-3 fatty acids?
An excessive intake of omega-6 fatty acids relative to omega-3 fatty acids may contribute to inflammation and certain chronic diseases.
- How are lipids involved in the synthesis of lipoproteins in the liver?
The liver synthesizes lipoproteins that transport lipids in the bloodstream, including VLDL, LDL, and HDL.
- What is the connection between lipids and gallstones?
An imbalance of cholesterol and bile salts in the gallbladder can lead to the formation of gallstones, which can be composed of cholesterol or other substances.
Kindly note that the information provided here is for educational purposes only and should not replace professional medical advice. If you have specific health concerns or questions related to lipids or any other medical condition, it is essential to consult with a healthcare professional.