Gluconeogenesis Mechanisms
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Questions and Answers

What is the primary function of glucagon in relation to glucose metabolism?

  • To inhibit the production of glucose from lactate
  • To promote the storage of glucose as glycogen
  • To enhance the uptake of glucose by muscle cells
  • To stimulate the conversion of glycogen to glucose (correct)

    • In which organs does gluconeogenesis primarily occur?

  • Adipose tissue and brain
  • Liver and cortex of kidneys (correct)
  • Liver and muscles
  • Heart and pancreas

    • Which hormone is responsible for stimulating glycogenesis?

  • Adrenaline
  • Glucagon
  • Insulin (correct)
  • Cortisol

    • What is the end product of glycogenolysis in muscle cells?

    <p>Glucose-6-phosphate</p> Signup and view all the answers

    Which factor does NOT promote the process of gluconeogenesis?

    <p>High levels of insulin</p> Signup and view all the answers

    What role does adrenaline play in glycogen metabolism?

    <p>It stimulates glycogenolysis for energy during stress</p> Signup and view all the answers

    What stimulates glycogen synthase to promote glycogenesis?

    <p>Glucose-6-phosphate</p> Signup and view all the answers

    Which statement accurately describes glycogen storage in the body?

    <p>Liver glycogen acts as a glucose reservoir for the whole body.</p> Signup and view all the answers

    What type of linkage is present in lactose between D-galactose and D-glucose?

    <p>β(1-4) glycosidic linkage</p> Signup and view all the answers

    Which statement best describes the sweetness and solubility of lactose anomers?

    <p>β-lactose is sweeter and more soluble than α-lactose</p> Signup and view all the answers

    Which compound is produced by the partial hydrolysis of starch by amylase?

    <p>Maltose</p> Signup and view all the answers

    What is the primary component of malt that leads to the formation of maltose?

    <p>Baked barley</p> Signup and view all the answers

    Why does lactase deficiency result in digestive issues when consuming milk?

    <p>It leads to the fermentation of lactose by bacteria</p> Signup and view all the answers

    Which type of sugar is classified as an aldohexose?

    <p>D-Glucose</p> Signup and view all the answers

    What distinguishes α and β anomers of a sugar?

    <p>The configuration around the anomeric carbon</p> Signup and view all the answers

    In what condition is glucose frequently utilized in medical treatment?

    <p>To treat hypoglycemia</p> Signup and view all the answers

    What defines a chiral center in a molecule?

    <p>An atom bonded to four different groups</p> Signup and view all the answers

    Which molecular configuration represents a molecule that is achiral?

    <p>A symmetrical molecule</p> Signup and view all the answers

    Which conditions favor the conversion of glucose to glycogen?

    <p>High glucose concentration and low energy demand</p> Signup and view all the answers

    What is the primary function of gluconeogenesis?

    <p>To produce glucose from non-carbohydrate sources</p> Signup and view all the answers

    What happens during glycogenolysis?

    <p>Breakdown of glycogen into glucose</p> Signup and view all the answers

    Which product of glycolysis is utilized for energy during cellular respiration?

    <p>Pyruvate</p> Signup and view all the answers

    What is the primary purpose of glycogenesis?

    <p>To store excess glucose for future use</p> Signup and view all the answers

    Which of the following accurately describes the products of glycolysis?

    <p>Two molecules of pyruvate, ATP, NADH, and water</p> Signup and view all the answers

    What is the primary role of gluconeogenesis in the human body?

    <p>To synthesize glucose from non-carbohydrate sources</p> Signup and view all the answers

    Which of the following cellular locations is associated with glycolysis?

    <p>Cytoplasm</p> Signup and view all the answers

    Which of the following statements about glycogenesis is correct?

    <p>It is the synthesis of glycogen from glucose.</p> Signup and view all the answers

    What is the main product produced during the reduction of glucose?

    <p>Sorbitol</p> Signup and view all the answers

    Which process directly uses ATP to convert glucose into glucose-6-phosphate?

    <p>Glycolysis</p> Signup and view all the answers

    Which enzyme is primarily responsible for catalyzing the conversion of glucose to glycogen?

    <p>Glycogen synthase</p> Signup and view all the answers

    Which of the following statements is true regarding glucose metabolism?

    <p>Glycogen can be broken down to glucose through glycogenolysis.</p> Signup and view all the answers

    What product results from the complete oxidation of glucose from glycolysis in aerobic conditions?

    <p>Carbon dioxide and water</p> Signup and view all the answers

    Which cellular process is responsible for generating glucose during fasting states?

    <p>Gluconeogenesis</p> Signup and view all the answers

    Which of the following processes directly produces glucose from glycogen?

    <p>Glycogenolysis</p> Signup and view all the answers

    During gluconeogenesis, which of the following substrates is NOT typically used to synthesize glucose?

    <p>Fatty acids</p> Signup and view all the answers

    In the process of glycogenesis, which enzyme is primarily responsible for adding glucose to the growing glycogen chain?

    <p>Glycogen synthase</p> Signup and view all the answers

    Which of the following statements about glycolysis is true?

    <p>It results in the production of 4 ATPs but has a net gain of 2 ATPs.</p> Signup and view all the answers

    What is the primary function of glycogenolysis in the human body?

    <p>To break down glycogen for energy</p> Signup and view all the answers

    Which of the following molecules can activate the process of glycogenolysis?

    <p>Glucagon</p> Signup and view all the answers

    Which pathway primarily occurs when blood glucose levels are low to replenish glucose?

    <p>Gluconeogenesis</p> Signup and view all the answers

    Which of the following factors does NOT positively influence glycogen synthesis?

    <p>Increased physical activity</p> Signup and view all the answers

    What is the end product of glycolysis when glucose is fully metabolized under anaerobic conditions?

    <p>Lactate</p> Signup and view all the answers

    What is the primary regulatory step unique to gluconeogenesis that bypasses glycolysis?

    <p>Conversion of oxaloacetate to phosphoenolpyruvate</p> Signup and view all the answers

    What is produced as a byproduct when glucose is converted to gluconic acid by glucose oxidase?

    <p>Hydrogen peroxide</p> Signup and view all the answers

    Which process describes the breakdown of glucose to provide energy?

    <p>Glycolysis</p> Signup and view all the answers

    What is the main end product of glucose after it undergoes reduction?

    <p>Sorbitol</p> Signup and view all the answers

    Which enzyme system is primarily responsible for measuring blood glucose levels?

    <p>Hexokinase</p> Signup and view all the answers

    During which process does glucose get converted into glycogen using non-carbohydrate sources?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What is the term for a molecule that has non-superimposable mirror images?

    <p>Chiral molecule</p> Signup and view all the answers

    In a Haworth projection, if a substituent points to the right in the Fisher structure, where does it point in the Haworth projection?

    <p>Down</p> Signup and view all the answers

    What classification is used for sugars that contain an aldehyde group?

    <p>Aldoses</p> Signup and view all the answers

    What type of anomer has the hydroxyl group (OH) on the same side of the oxygen ring?

    <p>α anomer</p> Signup and view all the answers

    Which molecule is considered tasteless and cannot be utilized by the human body?

    <p>L-glucose</p> Signup and view all the answers

    What is the classification of a monosaccharide that has six carbons?

    <p>Hexose</p> Signup and view all the answers

    What is a common use of 50% glucose solution in medical treatment?

    <p>To restore blood glucose concentrations</p> Signup and view all the answers

    What defines a chiral center in a molecule?

    <p>An atom with four different groups</p> Signup and view all the answers

    What type of linkage is primarily found in starch?

    <p>α-1,4 linkages</p> Signup and view all the answers

    Which of the following is NOT a characteristic of polysaccharides?

    <p>Can be digested by all organisms</p> Signup and view all the answers

    What defines the degree of branching in polysaccharides such as amylopectin?

    <p>Frequency of branch points</p> Signup and view all the answers

    Which characteristic distinguishes amylose from amylopectin?

    <p>Presence of branching</p> Signup and view all the answers

    Which factor primarily distinguishes different classes of carbohydrates?

    <p>Sugar residue</p> Signup and view all the answers

    Which polysaccharide is primarily used for energy storage in plants?

    <p>Starch</p> Signup and view all the answers

    What type of linkage connects repeating disaccharide units in bacterial cell walls?

    <p>β-1,4 bonds</p> Signup and view all the answers

    What is a key role of polysaccharides in the human body?

    <p>Form of stored chemical energy</p> Signup and view all the answers

    What is a major difference between starch and cellulose?

    <p>Cellulose has β-linkages, starch has α-linkages</p> Signup and view all the answers

    Which statement correctly describes the structure of Gram-positive bacteria?

    <p>They have a thick peptidoglycan wall.</p> Signup and view all the answers

    What type of polysaccharide consists of only one type of monosaccharide?

    <p>Homopolysaccharide</p> Signup and view all the answers

    What is the basic repeating unit of polysaccharides?

    <p>Monosaccharide</p> Signup and view all the answers

    What is the primary component of inulin?

    <p>Fructose</p> Signup and view all the answers

    How do animal cells use carbohydrates compared to plant cells?

    <p>They have a fluid extracellular matrix.</p> Signup and view all the answers

    Which polysaccharide resembles starch in structure but has more branches?

    <p>Glycogen</p> Signup and view all the answers

    What occurs during the condensation reaction forming polysaccharides?

    <p>A water molecule is released</p> Signup and view all the answers

    What is the function of carbohydrates in molecular recognition?

    <p>They are involved in cell signaling.</p> Signup and view all the answers

    What distinguishes Gram-negative bacteria from Gram-positive bacteria?

    <p>More complex structure with lipopolysaccharides</p> Signup and view all the answers

    Which statement reflects the importance of carbohydrates as a source of energy?

    <p>They are a preferential source of energy.</p> Signup and view all the answers

    What is one use of inulin in medical testing?

    <p>To assess kidney function.</p> Signup and view all the answers

    What causes the souring of milk?

    <p>Conversion of lactose to lactic acid by bacteria</p> Signup and view all the answers

    What type of sugar is lactose classified as?

    <p>Disaccharide</p> Signup and view all the answers

    Which anomer of lactose is sweeter and more soluble?

    <p>β-lactose</p> Signup and view all the answers

    What linkage is present in lactose between D-galactose and D-glucose?

    <p>β(1-4) glycosidic linkage</p> Signup and view all the answers

    Which statement accurately describes maltose?

    <p>It is formed by two D-glucose residues linked by an α(1-4) glycosidic linkage</p> Signup and view all the answers

    What occurs naturally only in milk?

    <p>Lactose</p> Signup and view all the answers

    What is the ratio of α and β anomers of lactose found in milk?

    <p>2:3</p> Signup and view all the answers

    What is maltose derived from?

    <p>Partial hydrolysis of starch by amylase</p> Signup and view all the answers

    Which compound is commonly used in baby food?

    <p>Maltose</p> Signup and view all the answers

    What causes the discomfort after consuming milk for some individuals?

    <p>Lactose intolerance due to inadequate lactase</p> Signup and view all the answers

    What role does glucagon play in the metabolic process of gluconeogenesis?

    <p>It activates the breakdown of glycogen.</p> Signup and view all the answers

    Which function is primarily associated with liver glycogen?

    <p>Glucose reservoir for the body during fasting.</p> Signup and view all the answers

    In what way does insulin influence glycogenesis?

    <p>It stimulates glycogenosis and inhibits glycogenolysis.</p> Signup and view all the answers

    How does adrenaline contribute to glycogen metabolism?

    <p>It stimulates glycogenolysis in muscle cells for energy.</p> Signup and view all the answers

    What is the primary substrate for gluconeogenesis when dietary carbohydrates are insufficient?

    <p>Lactate</p> Signup and view all the answers

    What type of sugars are classified as ketoses?

    <p>Sugars with a ketone group</p> Signup and view all the answers

    Which statement correctly describes chiral molecules?

    <p>They contain at least one chiral center.</p> Signup and view all the answers

    In the context of sugars, what distinguishes α anomers from β anomers?

    <p>The configuration of the hydroxyl group relative to the oxygen ring</p> Signup and view all the answers

    What configuration does D-glucose possess when compared to L-glucose in terms of taste?

    <p>D-glucose is sweet and nutritious</p> Signup and view all the answers

    How does a substituent's position in a Fisher projection affect its representation in a Haworth projection?

    <p>Right becomes down, left becomes up</p> Signup and view all the answers

    What is the overall function of a monosaccharide like D-glucose?

    <p>To provide a source of energy</p> Signup and view all the answers

    What defines a molecule as achiral?

    <p>It has four identical groups bonded to a central atom.</p> Signup and view all the answers

    Which of the following statements is true about the use of glucose in medical treatment?

    <p>Glucose 50% solution is used in hypoglycemia treatment</p> Signup and view all the answers

    What is the primary role of galactose in the human body?

    <p>Component of glycoproteins in brain tissue</p> Signup and view all the answers

    How is fructose structurally related to glucose?

    <p>It is a ketose with a different arrangement of atoms</p> Signup and view all the answers

    What type of bond links the monosaccharide units in a disaccharide?

    <p>Glycosidic bond</p> Signup and view all the answers

    Which statement best describes sucrose?

    <p>It is commonly found in fruits and vegetables</p> Signup and view all the answers

    What is a characteristic feature of cellobiose?

    <p>It contains two beta-D-glucose units</p> Signup and view all the answers

    Why is fructose used as a dietary sugar?

    <p>It requires less quantity for the same sweetness</p> Signup and view all the answers

    What type of oligosaccharide is maltose classified as?

    <p>Homo oligosaccharide</p> Signup and view all the answers

    What makes sucrose a non-reducing sugar?

    <p>It lacks free hemiacetal form</p> Signup and view all the answers

    In what medical conditions is fructose commonly administered intravenously?

    <p>Uncontrolled diabetes and hepatic disease</p> Signup and view all the answers

    Which of the following accurately describes the glycosidic linkage in di- and oligosaccharides?

    <p>It forms between two OH groups of monosaccharides</p> Signup and view all the answers

    What characteristic distinguishes amylose from amylopectin?

    <p>Amylose adopts a helical conformation in water.</p> Signup and view all the answers

    Which property is not associated with cellulose?

    <p>It contains only α(1,4) glycosidic bonds.</p> Signup and view all the answers

    What is produced when cellulose undergoes complete hydrolysis?

    <p>Glucose</p> Signup and view all the answers

    Why can humans not digest cellulose found in grass?

    <p>Humans have a deficiency of cellulase enzymes.</p> Signup and view all the answers

    What is the role of cellulases found in some bacteria?

    <p>To break down cellulose into glucose.</p> Signup and view all the answers

    What color does iodine produce when it interacts with amylose?

    <p>Blue</p> Signup and view all the answers

    What structural feature contributes to the mechanical strength of plant fibers?

    <p>Hydrogen bonding between polysaccharide chains</p> Signup and view all the answers

    What type of linkage is primarily found in cellulose?

    <p>b(1,4) glycosidic bonds</p> Signup and view all the answers

    Which of the following is not a composition element of wood cellulose?

    <p>Glucose polymers</p> Signup and view all the answers

    What feature allows animals such as cows to digest cellulose from grass, unlike humans?

    <p>Presence of specialized digestive bacteria</p> Signup and view all the answers

    Which type of linkage is primarily found in amylose?

    <p>α-1,4 glycosidic bonds</p> Signup and view all the answers

    What distinguishes amylopectin from amylose?

    <p>Amylopectin has α-1,6 linkages at branching points.</p> Signup and view all the answers

    Which property is true for polysaccharides?

    <p>They can serve as both storage and structural components.</p> Signup and view all the answers

    Which of the following represents a key difference between starch and cellulose?

    <p>Starch can be metabolized by humans, but cellulose cannot.</p> Signup and view all the answers

    What is the primary repeating unit in polysaccharides?

    <p>Monosaccharides</p> Signup and view all the answers

    What is one of the parameters to distinguish between different polysaccharides?

    <p>Degree of branching in the polymer chain</p> Signup and view all the answers

    Which type of polysaccharide is known for its role as an energy store in plants?

    <p>Starch</p> Signup and view all the answers

    How does glycogen compare to amylopectin in terms of branching?

    <p>Glycogen is more highly branched than amylopectin.</p> Signup and view all the answers

    Which structure is characterized by having a linear chain of D-glucose with links formed by β-1,4 glycosidic bonds?

    <p>Cellulose</p> Signup and view all the answers

    What happens during the formation of polysaccharides?

    <p>A water molecule is released.</p> Signup and view all the answers

    Study Notes

    Metabolic Pathways

    • Neoglucogenesis cycle recycles lactate (from muscles and RBCs) and glycerol (from adipose tissue) into glucose.
    • Takes place predominantly in the liver and kidneys' cortex.
    • Activated under low carbohydrate intake to fulfill glucose needs.

    Hormonal Regulation

    • Glucagon, secreted by pancreatic α-cells, plays a crucial role in increasing blood glucose levels.
    • Regulates conversion between fructose 1,6-bisphosphate and fructose 6-phosphate, promoting gluconeogenesis.

    Glycogenesis

    • Glycogenesis is the conversion of glucose into glycogen for storage in the liver and muscles.
    • Essential for blood sugar maintenance and immediate energy supply during fasting.
    • Liver glycogen acts as a reservoir for the entire body; muscle glycogen provides local energy for muscle contraction.

    Glycogenesis Regulation

    • Insulin stimulates glycogenesis by activating glycogen synthase and inhibiting glycogenolysis.
    • Glucagon stimulates glycogenolysis while inhibiting glycogenesis.
    • Adrenaline triggers glycogenolysis in muscle cells for quick energy release during stress.
    • Allosteric regulation involves glucose-6-phosphate, which can activate glycogen synthase.

    Glycogenolysis

    • Glycogenolysis is the breakdown of glycogen to release glucose, primarily occurring in the liver and kidneys.
    • In muscle cells, it produces glucose-6-phosphate for local energy requirements.

    Glucose Measurement

    • Glucose oxidase enzyme converts glucose to gluconic acid and hydrogen peroxide; detection methods involve photometric or electrical analysis.
    • Test methods include Testape for urine glucose and Dextrostix for blood glucose.

    Esterification Reactions

    • Hydroxyl groups in sugars can react with acids, forming phosphate esters, key intermediates in carbohydrate breakdown.

    Reduction and Sugar Alcohols

    • Aldehydes can be reduced to primary alcohols, producing sugar alcohols like sorbitol, a common food and cosmetic moisturizing agent.

    Glycolysis

    • Glycolysis is the breakdown of glucose to produce energy (pyruvate, ATP, NADH) occurring in the cytoplasm without oxygen.

    Gluconeogenesis

    • Gluconeogenesis synthesizes glucose from non-carbohydrate sources (amino acids, lactate), vital during fasting.

    Carbohydrate Structures

    • Sugars can be represented in straight chain (Fischer projections) or cyclic forms (Haworth projections).
    • D- and L-sugars are enantiomers with different optical rotations.

    Chirality

    • Chiral centers have four distinct groups bonded to an atom; chiral molecules cannot superimpose their mirror images.

    Monosaccharide Classification

    • Monosaccharides classified as aldoses or ketoses depending on functional groups, further divided based on carbon count (trioses to hexoses).

    D-Glucose

    • D-Glucose, also known as blood sugar, is the most abundant and critical for human metabolism, found in ripe fruits.

    Use of Monosaccharides

    • 50% glucose solution is hypertonic, utilized in medical treatment to restore blood glucose levels, especially in hypoglycemia.

    Starch and Cellulose

    • Starch consists of amylose and amylopectin; iodine testing yields a blue color indicative of starch presence.
    • Cellulose, a linear homopolymer of β-D-glucose, contributes to plant fiber strength.

    Lactose

    • Lactose, or milk sugar, is produced in mammalian glands from glucose, occurring in a mix of α and β forms.

    Disaccharides

    • Maltose, formed from starch hydrolysis, is linked by a α(1→4) glycosidic bond and useful in baby foods and other products.

    Health Note

    • Lactose intolerance causes digestive issues in some individuals due to insufficient β-galactosidase enzyme, affecting milk consumption.

    Structural Representation of Sugars

    • Sugars can be represented in straight chain forms including Fischer projections and perspective structural formulas.
    • D-sugars have optical rotation properties; L-amino acids do not.
    • Haworth projections are more realistic representations, where substituents' orientation differs from Fischer projections.

    Chirality

    • A chiral center has four different substituents, leading to non-superimposable mirror images.
    • Chiral molecules differ from achiral molecules, which have superimposable mirror images.

    Classification and Nomenclature of Monosaccharides

    • Monosaccharides are classified as aldoses (aldehyde group) or ketoses (ketone group).
    • Classified further by carbon count: trioses, tetroses, pentoses, and hexoses.

    D-Glucose

    • Known as grape sugar, dextrose, or blood sugar; most abundant and nutritionally significant.
    • Sweetness and nutritional value are high; present in ripe fruits with 20-30% glucose by mass.
    • D-glucose is utilized by cells for energy, unlike L-glucose which is tasteless and non-utilizable.

    Uses of Monosaccharides

    • 50% glucose solution is hypertonic and useful for restoring blood glucose levels during hypoglycemia.
    • No hemiacetal formation occurs due to glycosidic linkages; open-chain form is not possible.

    Lactose

    • Known as milk sugar, occurs naturally solely in milk.
    • Enzymes synthesize lactose from glucose; comprises D-galactose and D-glucose linked by β(1-4) glycosidic linkage.
    • Contains both α and β anomers in a 2:3 ratio; β-lactose is sweeter and more soluble. Souring of milk is caused by conversion to lactic acid by bacteria.

    Maltose

    • Also known as malt sugar, originates from starch hydrolysis by amylase.
    • Found in baby food and malted milk; formed from two D-glucose residues linked by an α(1-4) glycosidic bond.

    Uses of Disaccharides

    • Maltose can derive from icodextrin used in dialysis.
    • Sucrose is often added to medications to improve taste; Iron sucrose treats iron deficiency.

    Polysaccharides

    • Composed of repeating monosaccharide units linked by glycosidic bonds, releasing water during formation.
    • Identifiable by monosaccharide type, polymer length, glycosidic linkage type, and branching degree.

    Types and Functions of Polysaccharides

    • Homoglycans include amylose (linear α-D-glucose) and amylopectin (branched α-D-glucose).
    • Starch is a combination of amylose and amylopectin; glycogen resembles amylopectin but is more branched.
    • Cellulose features a linear D-glucose chain with β-1,4 linkages.

    Starch Characteristics

    • Starch consists of polymers of D-glucose, with α-linkages found in starch and β-linkages in cellulose.
    • Amylopectin has branches every 12 to 30 glucose residues; starch serves as an energy reserve in plants.

    Carbohydrates in Cell Structures

    • Bacterial cell walls are composed of carbohydrates; gram-positive bacteria have thick peptidoglycan walls, while gram-negative have more complex structures.
    • Plant cells utilize cell walls for stability; animal cells utilize an extracellular matrix for dynamic structural needs.

    Biomedical Importance of Carbohydrates

    • Carbohydrates are primary energy sources, store energy, form cellular structures, and assist in molecular recognition.

    Glucose Measurement Techniques

    • Glucose oxidase converts glucose into gluconic acid and hydrogen peroxide, enabling urine and blood glucose measurement.
    • Various enzymatic methods are used, including glucose oxidase, glucose dehydrogenase, and hexokinase.

    Esterification and Oxidation Reactions

    • Hydroxyl groups of sugars can form esters, typically with phosphates.
    • Oxidation converts aldehydes into carboxylic acids; reduction turns aldehydes into sugar alcohols (Alditols), such as sorbitol.

    Glycolysis and Gluconeogenesis

    • Glycolysis breaks down glucose to produce pyruvate, ATP, and NADH in the cytoplasm without oxygen.
    • Gluconeogenesis allows the production of glucose from non-carbohydrate sources to regulate blood glucose levels during deprivation.

    Structural Representation of Sugars

    • Sugars can be represented in straight chain form through Fisher projections or perspective structural formulas.
    • Haworth projections offer a more realistic depiction of sugars compared to Fisher projections.
    • In Haworth projections, substituents that are right in Fisher are down and those that are left are up.

    Enantiomers

    • D and L configurations indicate the spatial arrangement of glyceraldehyde.
    • D-sugars possess measurable optical rotation, while L-amino acids do not.

    Chirality

    • Chiral centers have four distinct groups attached, leading to non-superimposable mirror images.
    • Achiral molecules have superimposable mirror images.

    Classification and Nomenclature

    • Monosaccharides are classified as aldoses (aldehyde group) or ketoses (ketone group).
    • Length classification includes trioses (3 carbons), tetroses (4), pentoses (5), and hexoses (6).

    D-Glucose (Aldohexose)

    • Known as grape sugar and the most abundant sugar in nature.
    • Essential for human nutrition; found at high concentrations in ripe fruits (20-30% glucose).
    • D-glucose is sweet and nutritious, while L-glucose is tasteless and unusable by the body.

    Uses of Monosaccharides

    • A 50% glucose solution is hypertonic and restores blood glucose in hypoglycemia.
    • Galactose is vital for brain function, synthesized in mammary glands, and crucial for glycoprotein formation.

    D-Fructose (Ketohexose)

    • Also called levulose or fruit sugar, found in many fruits and the sweetest sugar.
    • Used for energy in patients with hepatic disease or uncontrolled diabetes.
    • Structurally similar to glucose from carbon 3 to 6.

    Disaccharides

    • Composed of two monosaccharide units linked by glycosidic bonds.
    • Examples include sucrose (table sugar), lactose, and maltose.

    Glycosidic Linkage

    • Links two monosaccharides in disaccharides, formed between hydroxyl groups of the monomers.

    Polysaccharides

    • Composed of repeating monosaccharide units linked by glycosidic bonds.
    • Identified by the type of monosaccharide, length, type of linkage, and branching degree.

    Types of Polysaccharides

    • Homoglycans (e.g., starch, cellulose) and heteroglycans.
    • Starch consists of amylose (linear chains) and amylopectin (branched chains).
    • Glycogen is a highly branched polymer of glucose for energy storage.

    Starch and Cellulose

    • Starch is digestible for humans, while cellulose (β-1,4 linkages) is not, creating structural importance in plants.
    • Iodine stains starch blue due to helical structure of amylose.

    Glycogen

    • Serves as a glucose reservoir, particularly during fasting.
    • Glycogenesis converts glucose to glycogen, primarily in liver and muscle for energy storage.
    • Regulation involves hormones: insulin stimulates glycogenesis, while glucagon promotes glycogenolysis.

    Glycogenolysis

    • Process of degrading glycogen for glucose production, occurring primarily in liver and kidney cells for blood sugar maintenance.

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