Which category do Sphingomyelin, Plasmalogens, and Cardiolipin belong to? A) Neutral Fats (Triglycerides/Triacylglycerol) B) Derived Lipids C) Fatty Acids D) Compound Lipids E) Cholesterol and Sterols
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What are the most important sterols in the human body?
Cholesterol
What are the three types of derived lipids?
Sphingomyelin, Plasmalogens, Cardiolipin
What is a fatty acid?
An organic acid that occurs in a natural triglyceride
What are substituted fatty acids?
Hydroxy fatty acid and methyl fatty acid, in which one or more of the hydrogen atoms have been replaced by – OH or – CH3 group
What is the structure of cholesterol's nucleus?
Cyclopentanoperhydrophenanthrene nucleus
Give examples of lipids.
Fats, oils, waxes and related compounds
Give an example of a saturated fatty acid with 10 carbon atoms.
Caproic acid C5H11COOH
How many double bonds are present in linolenic acid series?
Three
What are the two types of fatty acids based on the presence of double bonds?
Saturated FA (contain no double bonds) and Unsaturated FA (contain one or more double bonds)
What are neutral fats?
Tri-esters of glycerol with various fatty acids.
Where are sulpholipids present in the body?
They are present in various tissues including liver, kidney, testes, brains, and certain tumors.
Where is cholesterol synthesized in the body from?
AcetylCoA
What does Phosphatidyl Choline (Lecithin) yield on hydrolysis?
Glycerol, fatty acids, phosphoric acid, and nitrogenous base choline
What do R1, R2, R3 represent in neutral fats?
Fatty acid chains which may or may not all be the same.
What is the normal level of serum total cholesterol in an adult?
150 to 250 mg
Where do cerebrosides (glycosphingosides) occur in large amounts?
They occur in large amounts in the white matter of the brain and in the myelin sheaths of nerves.
What are examples of phospholipids?
Phosphatidyl choline (Lecithin), Cephalin, Phosphatidylserine, Phosphatidic acid
What are the dietary sources of linoleic acid?
Peanut oil, corn oil, cottonseed oil, soya bean oil and egg yolk.
What are the types of lipids that contain nitrogen but no nitrogenous base?
Kerasin, Cerebron, Nervon, and Oxynervon.
What do lipoproteins contain as a prosthetic group to proteins?
lipids
In which solvents is cholesterol soluble?
Ether, chloroform, hot alcohol, ethyl acetate, and vegetable oils
What is the difference between oil and fat in terms of physical state at room temperature?
Oil is liquid at room temperature, while fat is solid under the same conditions
What does the '18' in 18:1;9 represent in the shorthand notation for a fatty acid?
Number of carbon atoms
What does the '1' in 18:1;9 represent in the shorthand notation for a fatty acid?
Number of double bonds
What do saturated acids end in?
Saturated acids end in 'anoic', for example, octanoic acid.
How do unsaturated acids end?
Unsaturated acids end in 'enoic', for example, octadecenoic acid (oleic acid).
What does Δ9 denote in fatty acid naming?
Δ9 denotes a double bond between C9 and C10.
What are neutral fats?
Tri-esters of fatty acids with glycerol
What is the precursor for prostaglandins and leukotrienes in the body?
Arachidonic acid
What is the general formula for arachidonic acid?
CnH2n – 7 COOH
What is the range of chain length for fatty acids?
C4 to C24
Where are cyclic fatty acids present?
In some seeds
How are emulsions formed and what stabilizes them?
Emulsions are larger in size and formed when non-polar lipids (e.g. T-G) are mixed with water (aqueous medium). They can be stabilized by emulsifying agents such as amphipathic lipids (e.g. phosphatidyl choline). Emulsifying agents form a surface layer separating the main bulk of non-polar material from the water.
How much cholesterol does a hen's egg give?
250 mg
Where does Coprosterol occur?
Coprosterol (Coprostanol) occurs in faeces by reduction of cholesterol by bacteria.
Name some other steroids besides Coprosterol and Sitosterol.
Other steroids include bile acids, adrenocortical hormones, gonadal hormones, D vitamins, cardiac glycosides, and some alkaloids.
What effect does the ingestion of fats rich in essential fatty acids have on fibrinolytic activity?
Increase in fibrinolytic activity follows the ingestion of fats rich in essential fatty acids.
What are eicosanoids derived from?
Eicosapolyenoic fatty acids
What is cholesterol?
Cholesterol is a type of lipid molecule found in the cell membranes and is a precursor for the synthesis of steroid hormones, bile acids, and vitamin D.
What is the difference between 7-dehydrocholesterol and cholesterol?
It differs by a second double bond, between C7 and C8
What are the physiological sources of glycerol?
The physiological sources of glycerol include endogenous source from the lipolysis of fats in adipose tissue and exogenous source from dietary intake, with 22% of glycerol directly absorbed into the portal blood from the gut.
What are some examples of derived lipids?
Obtained by hydrolysis of lipids in group 1 and 2, that still possess the general characteristics of lipids.
Where is squalene found?
Found in human sebum, shark and liver of other mammals.
What are the constituents of natural membranes including cells and organelles membranes?
Lipoproteins and phospholipids
What are the fat soluble vitamins that require lipids for absorption?
Vitamins A, D, E and K
What is the general formula for oleic acid?
Cn H2n – 1 COOH
Where is phytanic acid found?
In butter
What are sulpholipids known to contain?
Contain sulphate groups
How can glycerol be converted in the body?
Glycerol can be converted to glucose or glycogen by gluconeogenesis.
What are Vit A and Vit D esters?
Palmitic or stearic acids esters of Vit A (Retinol) or Vit D respectively.
What is the structural configuration of naturally occurring fats?
D-structural configuration.
What are the esters of fatty acids with various alcohols?
Simple Lipids
What is the clinical significance of estimating lecithin phosphorus ratio in amniotic fluid?
It is clinically useful in predicting adequate fetal lung maturity and determining whether a fetus will develop respiratory distress after delivery.
What is glycerol?
Glycerol is the simplest trihydric alcohol containing three hydroxyl groups in the molecule.
What is the significance of gangliosides in the body?
They serve as specific membrane binding sites (receptor sites) for circulating hormones, thus influencing various biochemical processes in the cell.
What are the products of hydrolysis of gangliosides?
A long chain fatty acid, alcohol (sphingosine), and a carbohydrate moiety containing glucose, galactose, N-acetyl galactosamine, and N-acetyl neuraminic acid (sialic acid).
What is the structure of cerebrosides (glycosphingosides)?
Cerebrosides have no glycerol, no phosphoric acid, and no nitrogenous base.
What are lipids composed of?
Alcohol and fatty acids, but some contain phosphoric acid, nitrogenous base and carbohydrates
What is the general formula for saturated fatty acids?
CnH2n+1 COOH
What are compound lipids?
Esters of fatty acids containing other groups in addition to alcohol and fatty acids.
What are the physical properties of neutral fats?
Colorless, odorless, and tasteless substances. Insoluble in water but soluble in organic fat solvents.
How can fats be hydrolyzed?
Fats may be hydrolyzed by superheated steam, by acids or alkalis, or by lipases (the specific fat-splitting enzymes).
What does the '9' in 18:1;9 represent in the shorthand notation for a fatty acid?
Position of the double bond
Why must essential fatty acids be provided in the diet?
They cannot be synthesized in the body
What is the difference between 'cis' and 'trans' forms in terms of the orientation of radicals around the double bond?
'Cis' form has radicals on the same side of the bond, while 'trans' form has radicals on the opposite side.
What is the biomedical importance of lipids?
Lipids play a crucial role in energy storage, insulation, protection of vital organs, and as components of cell membranes.
In which diseases have metabolic defects of essential fatty acids been noted?
Metabolic defects of essential fatty acids, linked to dietary insufficiency, have been noted in different diseases e.g. cystic fibrosis, hepatorenal syndrome, Crohn’s disease.
What are compound lipids?
Compound lipids are lipids that contain fatty acids, a phosphate group, and a simple organic molecule.
What are the functions of Essential Fatty Acids (EFA) in the body?
Structural elements of tissues, structural element of gonads, synthesis of prostaglandins and other compounds, structural element of mitochondrial membrane, serum level of cholesterol, effect on clotting time.
What risk do people with familial hypercholesterolemia have?
Higher risk of heart disease and death at a younger age
What is the molecular formula of cholesterol?
C27H45OH
What are the four important types of cerebrosides isolated from the brain?
GM-1, GM-2, GM-3, and GD-3.
What are some exogenous sources of cholesterol?
Butter, cream, milk, egg yolk, meat
What is the biomedical importance of Sitosterol?
Sitosterol may decrease intestinal absorption of both exogenous and endogenous cholesterol, thus lowering the blood cholesterol level.
What is the biomedical importance of lipids?
Dietary constituent, source of energy in the body, yields more energy per gram compared to carbohydrates, can be stored in the body in unlimited amount, and lipid deposits in the body exert insulating effect and provide padding and protection around internal organs.
How are fatty acids named?
Fatty acids are named after the hydrocarbon with the same number of carbon atoms, with 'oic' being substituted for the final 'e' in the name of the hydrocarbon.
What is Dehydrocholesterol?
Dehydrocholesterol is a pro-vitamin D.
What are the transporters of triglycerides and cholesterol in the body?
Lipoproteins
What is the most abundant polyenoic fatty acid present in retinal photoreceptor membranes?
Docosahexaenoic acid is the most abundant polyenoic fatty acids present in retinal photoreceptor membranes.
What is the alcohol group in Phosphoinositides?
Inositol
What is the role of linolenic acid in vision?
Linolenic acid is necessary in the diet for optimal vision as it enhances the electrical response of the photoreceptors to illumination.
What are neutral fats also known as?
Neutral fats are also known as triglycerides or triacylglycerol.
What is the most common sterol in the human body?
Cholesterol is the most common sterol in the human body.
What are some uses of liposomes in the medical field?
i. Can be used in combination with tissue-specific antibodies, as carriers of drugs in the circulation, targeted to specific organs, e.g. in cancer therapy, ii. Used for gene transfer into vascular cells, and iii. As carriers and delivery agents for topical and transdermal drugs and cosmetics
What are Stigmasterol and Sitosterol?
Stigmasterol and Sitosterol occur in higher plants and have no nutritional value for human beings.
What is the shorthand notation for CH3(CH2)7 - CH=CH(CH2)7 - COOH?
18:1;9
How are lower fatty acids classified?
Lower fatty acids have 10 carbon atoms or less.
What is the defining characteristic of unsaturated fatty acids?
They contain at least one C - C double bond in the structure.
What are the three polyunsaturated fatty acids considered essential fatty acids?
Linoleic acid, linolenic acid, and arachidonic acid
What may happen if there is a lack of essential fatty acids in the diet?
It may lead to growth retardation and other deficiency symptoms
What information does a popular convention formula for fatty acids show?
The number of carbon atoms, the number of double bonds, and the positions of the double bonds.
Where is Phosphatidyl Choline (Lecithin) distributed in animals?
Liver, brain, nerve tissues, sperm and egg-yolk
Why are lipids generally insoluble in water?
Lipids are generally insoluble in water because they mainly contain nonpolar hydrocarbon groups.
Where are lipases found?
(a) Lingual lipase (saliva), (b) Gastric lipase (gastric juice), (c) Pancreatic lipase (pancreatic juice), (d) Intestinal lipase (intestinal epithelial cell), (e) Adipolytic lipase (adipose tissue), (f) Serum lipase
What is saponification?
Hydrolysis of a fat by an alkali. Products are glycerol and the alkali salts called 'soaps'.
What additive reactions do unsaturated fatty acids present in neutral fat exhibit?
Unsaturated fatty acids present in neutral fat exhibit all the additive reactions, i.e. hydrogenation, halogenation, etc.
What do unsaturated fatty acids undergo in oxidation?
Unsaturated fatty acids e.g. linseed oil undergo spontaneous oxidation at the double bond forming aldehydes, ketones and resins.
What is the variation in the location of the double bonds along the unsaturated fatty acid chain called?
Positional Isomers
What happens to essential fatty acids after isomerization and epimerization?
Essential fatty acids undergo β-oxidation after isomerization and epimerization, like other unsaturated fatty acids.
What are the major alcohols found in lipid molecules?
The major alcohols found in lipid molecules are glycerol and sphingosine.
What are examples of phospholipids?
Phosphatidyl choline (Lecithin), phosphatidyl ethanolamine (Cephalin), phosphatidyl inositol (Lipositol), phosphatidyl serine, plasmalogens, and sphingomyelins.
What are glycolipids?
Lipids that have a carbohydrate component and contain the alcohol sphingosine/sphingol, a nitrogenous base, and fatty acids, but not phosphoric acid or glycerol.
How are mono unsaturated fatty acids classified?
Mono unsaturated fatty acids contain one double bond.
What are the two types of isomers that occur in an unsaturated fatty acid?
Geometric Isomers and Positional Isomers
Which essential fatty acid can be used in the synthesis of arachidonic acid?
Linoleic acid
What is the characteristic arrangement of amphipathic lipids at oil-water interfaces?
The polar groups are in the water phase and the non-polar groups are in the oil phase.
What is the basic structure of biological membranes formed by amphipathic lipids?
Membrane bilayer.
What is the prerequisite for fat digestion and absorption from the intestine?
Micelles formation, facilitated by bile salts.
How are liposomes formed?
Liposomes are formed by sonicating an amphipathic lipid in an aqueous medium.
What are lipids?
Lipids are a diverse group of biomolecules that are insoluble in water but soluble in organic solvents.
Why can't essential fatty acids be synthesized in the body?
Introduction of additional double bonds in unsaturated fatty acid is limited to the area between the COOH group and the existing double bond and this is not possible between the CH3 group at the opposite end of the molecule and the first unsaturated linkage
In which body tissues is cholesterol found in largest amounts in normal human adults?
Brain and nervous tissue, liver, skin, intestinal mucosa
What is the major component of gallstones?
Cholesterol
In what forms does cholesterol occur?
Free and ester (bound) form
What is the characteristic structure of liposomes?
They consist of spheres of lipid bilayers that enclose part of the aqueous medium.
What are cholesterol esters?
Esters of fatty acids with cholesterol
What are some examples of Glycerophosphatides?
Phosphatidylethanolamine (cephalin), phosphatidylcholine (Lecithin), phospatidylserine, plasmalogens, phosphatidic acid, cardiolipins and phosphatides.
What is the alcohol group in Glycerophosphatides?
Glycerol
What causes rancidity in natural fats?
Rancidity is caused by oxidation or hydrolysis, resulting in an unpleasant odor and taste developed by most natural fats on aging.
What is the alcohol group in Phosphosphingosides?
Sphingosine (sphingol)
What are the two main types of derived lipids?
The two main types of derived lipids are fatty acids and alcohols.
What happens in the body when there is a deficiency of essential fatty acids?
Deficiency of essential fatty acids produces fatty liver.
What are the catabolized into simpler compounds for biosynthesis?
Lipids
From which dietary acid is docosahexaenoic acid formed?
Docosahexaenoic acid is formed from dietary linolenic acid.
What are waxes?
Esters of fatty acids with long straight chain alcohols
What are the essential fatty acids?
Essential fatty acids are fatty acids that cannot be synthesized by the body and must be obtained from the diet.