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Questions and Answers
What condition is characterized by the body's inability to metabolize galactose?
Which model of inheritance is associated with galactosemia?
What is the positive result indicated by a mucic acid test?
Which test can distinguish between aldehydes and ketones?
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What chemical change occurs during Benedict's test when reducing sugars are present?
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What type of bond is found in the structure of fructans?
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Which of the following statements about chitin is true?
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What is the main use of chitin in animals?
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What organism is primarily responsible for the production of dextran from sucrose?
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Which of the following best describes the composition of dextran?
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What two monosaccharides are obtained upon hydrolysis of sucrose?
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What is the primary component responsible for the structure of amylose?
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What type of carbohydrate is maltose classified as?
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Which of the following statements about raffinose is true?
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Which artificial sweetener is known for being calorie-free?
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What is the main consequence of lactose intolerance?
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Which enzyme is primarily responsible for hydrolyzing starch?
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Which sugar is referred to as milk sugar?
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What describes the structure of amylopectin?
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What is trehalose classified as?
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Which of the following is an example of a heteroglycan?
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What type of bond links monosaccharides in a disaccharide?
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What is the product of the enzymatic breakdown of cellulose?
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What is the structure of mucilage classified as?
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Which fatty acid configuration can lead to cardiovascular disorders?
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What is the main role of glycolipids in cell membranes?
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What is the impact of increased carbon chain length on the melting point of fatty acids?
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Where does fatty acid synthesis occur in the cell?
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What is a key byproduct of glycolysis that contributes to fatty acid synthesis?
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Which enzyme is responsible for converting Acetyl-CoA to Malonyl-CoA?
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What type of lipid is a triacylglycerol?
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What does the iodine number indicate about a lipid?
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Which of the following lipid types provides structural integrity to cell membranes?
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Which process takes place after condensation in fatty acid biosynthesis?
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Which type of fatty acids remain liquid at room temperature?
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What characteristic do steroid lipids possess?
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Which of the following substances are made from fatty acids?
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What happens to the degree of unsaturation as the iodine number increases?
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What is the primary use of mannitol derived from manna?
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Which amino sugar is derived from glucose?
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What occurs during the phosphorylation of glucose?
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What color does the Anthrone test produce when positive?
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What are the cyclic forms of monosaccharides commonly known as?
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What is the result of Tauber’s test?
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What does the Keller-Killiani test indicate?
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Which type of lipid provides the principal energy source for the body?
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What do fatty acids in the human body typically contain?
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Which test produces a cherry red color upon heating with a solution of benzidine?
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What is mannitol's role as an osmotic-diuretic?
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What is the result of the Seliwanoff’s test for a ketose?
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Which of these tests is specifically for distinguishing pentose from hexose sugars?
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What defines a class of compounds as lipids?
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Study Notes
Galactosemia
- A metabolic disorder where the body can't metabolize galactose due to an excess in the blood.
- Follows an autosomal recessive inheritance pattern, leading to a deficiency in the enzyme galactase.
- Diagnosed using the Mucic Acid Test which yields positive crystal formation and is also known as Galactaric Acid
Reducing Sugar
- A sugar that can be oxidized, indicated by the reduction of cupric hydroxide in alkaline solution to red cuprous oxide in Benedict's Test.
- Distinguished from ketones by Tollen's Test (Silver Mirror Test). Aldehydes readily oxidize, ketones do not.
- Maltose is a reducing sugar composed of two glucose units (GLU + GLU).
- Lactose (milk sugar) is also a reducing sugar, composed of glucose and galactose (GLU + GAL).
- Lactose intolerance occurs due to lack of the enzyme lactase which is needed for lactose hydrolysis.
- Sucrose is a non-reducing sugar.
Carbohydrates: A Comprehensive Overview
- Sugars, starches, and fibers are complex carbohydrates.
- Monosaccharides are simple sugars like glucose, fructose, and galactose.
- Disaccharides are composed of two monosaccharide units linked via a glycosidic bond.
- Oligosaccharides consist of 3-10 monosaccharide units.
- Polysaccharides are made up of many (>10) monosaccharide units linked together by glycosidic bonds.
- Homoglycans consist of one type of monosaccharide, while heteroglycans contain multiple types of monosaccharides.
Key Polysaccharides
-
Starch: Temporary carbohydrate storage in plants, comprised of amylose and amylopectin.
- Amylose: Linear, composed of 250-300 D-glucopyranose units linked by α-1,4 glycosidic bonds, soluble in water.
- Amylopectin: Branching (every 25 units), composed of 1000 or more glucose units with α-1,4 and α-1,6 linkages.
- Glycogen: The carbohydrate storage form in animals.
- Cellulose: A structural component of plant cell walls, composed of linear chains of glucose units linked by β-1,4 glycosidic bonds, insoluble in water.
Other Notable Polysaccharides
- Dextran: A glucose polymer found in certain bacteria, used in treatment of shock.
- Chitin: A structural component of arthropod exoskeletons and fungal cell walls, composed of N-acetyl-β-D-glucosamine units.
Visual Representation of Carbohydrates
- The structure of carbohydrates is depicted using Fischer, Haworth, and Conformational formulas.
- Nearly all naturally occurring sugars are Dextro sugars.
- The Haworth projection shows the ring structure of sugars with specific positions for hydroxyl groups.
Amino Sugars
- Building blocks of polysaccharides found in chitin and hyaluronic acid.
- Common amino sugars include glucosamine, galactosamine, and mannosamine.
Tests for Carbohydrates
- Molisch Test: A general test for all carbohydrates.
- Anthrone Test: Used to identify carbohydrates, specifically for the detection of furfural formation, which results in a blue-green solution.
- Tauber's Test: Specific for pentose sugars, producing a cherry red color when heated with a solution of benzidine in glacial acetic acid.
- Tauber's Aminoguanidine test: Used to differentiate between aldose and ketose sugars.
- Bial's Orcinol Test: Distinguishes pentoses from hexoses by furfural formation.
- Seliwanoff's Test: Distinguishes between ketose and aldose sugars.
- Keller-Killiani Test: Identifies deoxy sugars, forming a reddish-brown layer at the junction of liquids.
- Moore's Test: Identifies reducing sugars based on the production of caramel odor from heating with alkali solution.
Lipids
- Major energy source for the body, provide hydrophobic barrier for cell and subcellular structures.
- Heterogeneous group of compounds characterized by hydrophobic properties.
- Consist of hydrophobic hydrocarbon chains with a terminal carboxyl group.
- Contain an even number of Carbon Atoms that are either saturated or unsaturated.
- Exist freely in the body as unesterified forms and fatty acyl esters.
Lipids
- Lipids are a diverse group of organic compounds that are insoluble in water but soluble in organic solvents.
- Common examples of lipids include fats, oils, waxes, steroids, and phospholipids.
- Lipids are essential components of cell membranes, hormones, and energy storage.
- Lipids can be classified into different types based on their structure and function.
Steroids
- Steroids are a class of lipids that have a characteristic four-ring structure.
- Examples of steroids include cholesterol, testosterone, estrogen, progesterone, aldosterone, cortisol, and bile salts.
Glycolipids
- Glycolipids are lipids with carbohydrates attached by a glycosidic bond.
- Glycolipids are important for maintaining the stability of cell membranes and facilitating cell recognition.
Characteristics of Fatty Acids
- Fatty acids are long-chain carboxylic acids that are an important component of lipids.
- Fatty acids have low water solubility.
- The solubility of fatty acids decreases with increasing chain length.
- Fatty acids can be saturated or unsaturated.
- Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.
- The melting point of fatty acids is influenced by both the length of the carbon chain and the degree of unsaturation.
- Longer chains increase melting point, while a greater degree of unsaturation decreases melting point.
- Saturated fatty acids are generally solid at room temperature, while unsaturated fatty acids are usually liquid.
Fatty Acid Synthesis
- Fatty acid synthesis occurs in the cytosol.
- Fatty acid synthesis requires Acetyl-CoA as a starting material.
- Acetyl-CoA is a byproduct of the decarboxylation of pyruvic acid in aerobic respiration.
- Pyruvic acid is a byproduct of the glycolysis reaction.
- Acetyl-CoA is converted to Acetyl-CoA ACP (acyl carrier protein).
- Malonyl-CoA is formed from Acetyl-CoA by the carboxylase enzyme.
- Malonyl-CoA is then converted to Malonyl-ACP by the acyl acp transferase enzyme.
- Acetyl-CoA ACP reacts with Malonyl ACP to undergo a condensation reaction.
- The condensation reaction results in the release of carbon dioxide and the formation of 3-ketoacyl-ACP.
- 3-ketoacyl-ACP is reduced to 3-hydroxyl-ACP by the B-ketoacyl-ACP reductase enzyme.
- This reduction requires the oxidation of NADPH to NADP.
- 3-hydroxyl-ACP undergoes dehydration to form Enoyl-ACP by the B-hydroxyl-ACP dehydrase enzyme.
- Enoyl-ACP is reduced to Acyl-ACP by the enoyl-ACP reductase enzyme.
- This reduction requires the oxidation of NADPH to NADP.
Types of Lipids
- Lipids can be classified into different types based on their structure and function.
- Simple lipids are the simplest type of lipid and are formed by the combination of fatty acids with alcohols.
Triacylglycerol
- Triacylglycerol, also known as triglyceride, is the simplest lipid, formed by combining fatty acids with glycerol.
- Triacylglycerols are a valuable form of energy storage and are important for regulating temperature.
Phospholipids
- Phospholipids are the most abundant type of lipid found in cell membranes.
- Phospholipids give the cell membrane structural integrity.
Iodine Number
- The iodine number refers to the number of grams of iodine absorbed by 100 grams of a substance under specific conditions.
- The iodine number reflects the degree of unsaturation in a substance.
- A low iodine number (<100) indicates that the substance is non-drying, while a higher iodine number (>120) indicates that it is drying.
- Melting point, specific gravity, and refractive index also help identify, determine purity, and measure the quality of lipids.
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Description
This quiz covers key concepts related to galactosemia, reducing sugars, and the classification of carbohydrates. Explore the metabolic processes, tests used for diagnosis, and understand the differences between various types of sugars. A great resource for students studying biochemistry and metabolism.
