أسئلة المحاضرة الثالثة بيو (قبل التعديل)
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Questions and Answers

What is the primary sugar acid in association with heparin?

  • Galacturonic acid
  • Glucuronic acid (correct)
  • Rhamnose
  • Mannuronic acid

    • Which of the following compounds is NOT a polysaccharide?

  • Sialic acid (correct)
  • Chondroitin
  • Heparin
  • Hyaluronic acid

    • What is attached to the core protein in cartilage to form its structure?

  • Nucleic acids
  • Amino acid sequences
  • Lipid molecules
  • Linear carbohydrate chains (correct)

    • Which of the following best describes the attachment of carbohydrate chains in cartilage?

    <p>Covalent bonds (B)</p> Signup and view all the answers

    What type of biological macromolecule primarily forms the backbone of cartilage?

    <p>Proteins (B)</p> Signup and view all the answers

    What type of polysaccharide is primarily used for storage in plants?

    <p>Starch (C)</p> Signup and view all the answers

    Which polysaccharide serves a structural function in plant cells?

    <p>Cellulose (D)</p> Signup and view all the answers

    Glycogen is primarily found in which type of organism?

    <p>Animals (A)</p> Signup and view all the answers

    Which of the following statements is true about cellulose?

    <p>It provides structural support in plant cell walls. (A)</p> Signup and view all the answers

    What classification does starch fall under?

    <p>Storage polysaccharide (D)</p> Signup and view all the answers

    What is the source of agar?

    <p>Marine red algae (C)</p> Signup and view all the answers

    Which of the following best describes agar?

    <p>A polysaccharide (A)</p> Signup and view all the answers

    In terms of chemical composition, agar is primarily what type of molecule?

    <p>Polysaccharide (B)</p> Signup and view all the answers

    Which characteristic is NOT associated with agar?

    <p>Soluble in cold water (C)</p> Signup and view all the answers

    What characteristic describes the structure of amylopectin?

    <p>A highly branched layer with branch points every 30 linkages (D)</p> Signup and view all the answers

    How often do branch points occur in amylopectin's structure?

    <p>Every 30 linkages (D)</p> Signup and view all the answers

    Which statement best describes the branching of amylopectin?

    <p>Branches occur at consistent intervals of every 30 linkages (C)</p> Signup and view all the answers

    What type of polysaccharide is amylopectin classified as?

    <p>A branched storage polysaccharide (D)</p> Signup and view all the answers

    What characteristic is true regarding the formation of cellulose in plants?

    <p>Formed of β-glucose units (D)</p> Signup and view all the answers

    Which statement accurately describes cellulose's role in plants?

    <p>It provides structural support in cell walls. (A)</p> Signup and view all the answers

    Which statement is true regarding the enzymatic process related to cellulose?

    <p>Cellulose hydrolysis is not significant in dietary processes. (A)</p> Signup and view all the answers

    In what way is cellulose different from starch in terms of structure and function?

    <p>Cellulose comprises β-glucose units while starch comprises α-glucose units. (D)</p> Signup and view all the answers

    What can be concluded about the importance of cellulose?

    <p>It is central to the structural framework of plant life. (B)</p> Signup and view all the answers

    What distinguishes homo-polysaccharides from hetero-polysaccharides in terms of monosaccharide composition?

    <p>Homo-polysaccharides contain only one type of monosaccharide, while hetero-polysaccharides contain more than one type.</p> Signup and view all the answers

    Explain how the classification of polysaccharides as homo or hetero relates to their functional roles in organisms.

    <p>Homo-polysaccharides typically serve storage or structural roles due to their uniform composition, whereas hetero-polysaccharides have diverse functions due to their varied monosaccharide types.</p> Signup and view all the answers

    What implications does the structural composition of homo-polysaccharides have on their digestibility?

    <p>The uniform nature of homo-polysaccharides can make them more easily digestible compared to hetero-polysaccharides, which may have complex structures.</p> Signup and view all the answers

    In the classification of polysaccharides, how does the presence of multiple monosaccharides influence the properties of hetero-polysaccharides?

    <p>The diversity in monosaccharides allows hetero-polysaccharides to exhibit unique properties, such as varying solubility, viscosity, and biological functions.</p> Signup and view all the answers

    How might the structural characteristics of homo-polysaccharides impact their storage capacities in biological systems?

    <p>The simplicity of homo-polysaccharides can enhance their efficiency in storage, allowing for quick mobilization of energy when needed.</p> Signup and view all the answers

    What is the primary role of glucose during fasting according to the content?

    <p>To maintain blood glucose levels.</p> Signup and view all the answers

    How does the breakdown of glucose contribute to bodily function during fasting?

    <p>It provides necessary energy to sustain vital functions.</p> Signup and view all the answers

    What physiological process occurs in the body to manage blood glucose levels when fasting?

    <p>Glycogenolysis, where glycogen is broken down into glucose.</p> Signup and view all the answers

    What is the significance of maintaining blood glucose levels during fasting?

    <p>It is essential for preventing hypoglycemia and ensuring proper brain function.</p> Signup and view all the answers

    What might happen if blood glucose levels drop too low during fasting?

    <p>It can lead to symptoms of hypoglycemia, such as dizziness and confusion.</p> Signup and view all the answers

    What role do glycosaminoglycans (GAGs) play in connective tissue?

    <p>GAGs contribute to the structure and function of connective tissue by providing hydration and elasticity, as well as forming a significant part of the extracellular matrix.</p> Signup and view all the answers

    How are proteoglycans formed and what is their significance in connective tissue?

    <p>Proteoglycans are formed by the covalent attachment of GAGs to core proteins, which is significant for forming a resilient extracellular matrix that supports cell adhesion and tissue structure.</p> Signup and view all the answers

    Describe the structural differences between cartilage and bone.

    <p>Cartilage is more flexible and has a gel-like matrix enriched with water and GAGs, while bone is rigid and consists of a mineralized matrix primarily made up of collagen and hydroxyapatite.</p> Signup and view all the answers

    What is the impact of age-related changes in connective tissue on mobility?

    <p>Age-related changes, such as decreased GAG content and hydration in connective tissue, lead to stiffer joints and reduced mobility, causing discomfort and pain.</p> Signup and view all the answers

    Why are glycosaminoglycans considered important for joint health?

    <p>GAGs play a vital role in joint health by retaining water and providing lubrication, which helps reduce friction between joint surfaces during movement.</p> Signup and view all the answers

    What is the glomerular filtration rate and why is it significant?

    <p>The glomerular filtration rate (GFR) measures how well the kidneys filter blood, indicating kidney function and health.</p> Signup and view all the answers

    How do bacteria in the gut of ruminants contribute to their digestion?

    <p>Bacteria in the gut of ruminants help break down complex carbohydrates and cellulose through fermentation, facilitating nutrient absorption.</p> Signup and view all the answers

    What factors can influence the glomerular filtration rate?

    <p>Factors such as blood pressure, hydration levels, and the presence of certain medical conditions can influence the GFR.</p> Signup and view all the answers

    What role do gut bacteria play in the metabolic processes of ruminants?

    <p>Gut bacteria play a crucial role by fermenting dietary fibers and synthesizing essential vitamins and fatty acids.</p> Signup and view all the answers

    Why is an accurate measurement of the glomerular filtration rate important in clinical settings?

    <p>An accurate GFR measurement is important to assess kidney health and guide treatment decisions for various renal conditions.</p> Signup and view all the answers

    How does the presence of glycoproteins on red blood cells determine a person's blood group?

    <p>The blood group is determined by the specific antigens present on the surface of red blood cells, which are types of glycoproteins.</p> Signup and view all the answers

    What role do blood group antigens play in transfusions?

    <p>Blood group antigens can trigger immune responses if incompatible blood is transfused.</p> Signup and view all the answers

    Describe the implication of blood group antigens in organ transplantation.

    <p>Blood group antigens must be compatible to prevent rejection of transplanted organs.</p> Signup and view all the answers

    In the context of blood grouping, what is the significance of glycoproteins?

    <p>Glycoproteins are significant as they form the specific antigens that determine the ABO blood types.</p> Signup and view all the answers

    What is the biochemical basis for the differences in human blood groups?

    <p>The biochemical basis is the variations in glycoproteins on red blood cells that express different antigens.</p> Signup and view all the answers

    What is the defining characteristic of homo-polysaccharides in terms of monosaccharide composition?

    <p>Homo-polysaccharides contain only one type of monosaccharide.</p> Signup and view all the answers

    How do hetero-polysaccharides differ from homo-polysaccharides?

    <p>Hetero-polysaccharides contain more than one type of monosaccharide.</p> Signup and view all the answers

    In the context of polysaccharides, what are homo-glycans and hetero-glycans?

    <p>Homo-glycans refer to homo-polysaccharides, while hetero-glycans refer to hetero-polysaccharides.</p> Signup and view all the answers

    What role do the types of monosaccharides play in determining the characteristics of polysaccharides?

    <p>The type of monosaccharides influences the structural and functional properties of the polysaccharides.</p> Signup and view all the answers

    How would you categorize a polysaccharide composed of glucose and fructose?

    <p>It would be categorized as a hetero-polysaccharide.</p> Signup and view all the answers

    What unique structural feature distinguishes glycosaminoglycans from other carbohydrates?

    <p>Glycosaminoglycans have a repeating disaccharide unit structure, which is often sulfated.</p> Signup and view all the answers

    Describe the primary function of dextran in biological systems.

    <p>Dextran primarily functions as an energy-storage polysaccharide in certain bacteria and yeast.</p> Signup and view all the answers

    In what way does inulin differ from starch and glycogen in terms of energy storage?

    <p>Inulin serves as a storage polysaccharide primarily in plants, but it is indigestible by humans, unlike starch and glycogen.</p> Signup and view all the answers

    How do proteoglycans contribute to the mechanical properties of connective tissue?

    <p>Proteoglycans trap water in the extracellular matrix, providing hydration and resilience to connective tissues.</p> Signup and view all the answers

    What role does cellulose play in the structural integrity of plant cells?

    <p>Cellulose provides rigidity and strength to plant cell walls, allowing plants to maintain their shape.</p> Signup and view all the answers

    What is the primary function of hyaluronic acid within the extracellular matrix?

    <p>It serves as a lubricant and acts as an anticoagulant.</p> Signup and view all the answers

    How does the presence of glycosaminoglycans (GAGs) affect the properties of connective tissue?

    <p>GAGs contribute to the hydrophilic nature and structural integrity of connective tissue.</p> Signup and view all the answers

    What role does the anticoagulant property of hyaluronic acid play in the body?

    <p>It helps prevent blood clotting, maintaining smooth blood flow.</p> Signup and view all the answers

    In what way does hyaluronic acid function in relation to lubrication?

    <p>It reduces friction between cells and tissues, facilitating smooth movement.</p> Signup and view all the answers

    Why is the presence of abundant hyaluronic acid important for connective tissues?

    <p>It enhances tissue hydration and resilience, supporting overall mechanical function.</p> Signup and view all the answers

    What is the main structural component of plant cell walls and what units is it formed of?

    <p>Cellulose, formed of β-glucose units.</p> Signup and view all the answers

    How is cellulose hydrolyzed and what dietary importance does it hold?

    <p>Cellulose is hydrolyzed by inulinase and has no dietary importance in humans.</p> Signup and view all the answers

    Why is cellulose considered the most abundant natural polymer found in the world?

    <p>Because it is present in the cell walls of nearly all plants.</p> Signup and view all the answers

    Discuss the significance of cellulose in relation to plant structural integrity.

    <p>Cellulose provides structural support to plants, enabling them to maintain shape and resist external pressure.</p> Signup and view all the answers

    In what way does cellulose contribute to the ecological system?

    <p>Cellulose serves as a source of energy for certain microorganisms and supports the food chain.</p> Signup and view all the answers

    How does the absence of inulinase in humans influence carbohydrate digestion, particularly for diabetic patients?

    <p>The absence of inulinase in humans prevents the hydrolysis of certain carbohydrates, making complex carbohydrates a suitable dietary option for diabetic patients to manage their blood sugar levels.</p> Signup and view all the answers

    What is the significance of resistance to hydrolysis by acid and digestive tract amylase for human dietary choices?

    <p>The resistance to hydrolysis allows certain carbohydrates to remain intact during digestion, thereby providing a controlled release of glucose, which is beneficial for blood sugar management.</p> Signup and view all the answers

    In what way might the dietary management of diabetic patients benefit from understanding the functionality of inulin?

    <p>Understanding inulin's functionality can guide diabetic patients in selecting foods that have a low glycemic index, thus preventing spikes in blood sugar levels.</p> Signup and view all the answers

    What role could inulin play in the diets of individuals with digestive disorders?

    <p>Inulin can act as a prebiotic, promoting beneficial gut bacteria, which may aid digestion and improve overall gut health for those with digestive disorders.</p> Signup and view all the answers

    Why is a diet emphasizing resistant carbohydrates beneficial for patients with diabetes?

    <p>A diet rich in resistant carbohydrates slows down glucose absorption, leading to improved glycemic control and reduced insulin requirements.</p> Signup and view all the answers

    Agar is derived from ______.

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

    Inulin is commonly found in various ______.

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

    Dextran is a polysaccharide that consists of ______ molecules.

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

    Dextrin is a form of carbohydrate that is derived from ______.

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

    Both amylopectin and glycogen are types of ______.

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

    Starch consists of two layers: amylose and ______.

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

    ______ is an animal starch that consists of α-glucose units.

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

    Amylose is the inner linear non-branching ______ of starch.

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

    Both starch and glycogen consist of α-D glucose units, also known as ______.

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

    Glycogen is characterized by its highly ______ structure.

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

    The carbohydrate part consists of ______ chains.

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

    These chains are attached to protein via OH of ______ and threonine residues.

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

    Glycoproteins are formed by the attachment of carbohydrates to ______.

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

    The amide N of ______ is involved in N-glycosidic bond formation.

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

    Glycoproteins could be found as ______.

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

    The most common storage ______ in plants is a polysaccharide.

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

    Major form of storage ______ in animals and the human body.

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

    The storage polysaccharide in plants is primarily ______.

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

    In addition to starch, another significant polysaccharide for storage in animals is ______.

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

    Plants primarily use ______ as a method for storing energy.

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

    Organisms secrete ______ (β- glucosidase) which can hydrolyze cellulose.

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

    ______ consists of α-D glucose units and is commonly known as animal starch.

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

    Starch is classified as a type of ______.

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

    The structure of amylopectin includes ______ points that create branching.

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

    Cellulose serves a ______ function in plant cells, providing structural support.

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

    Study Notes

    Polysaccharides (Glycans)

    • Polysaccharides are a type of carbohydrate that plays an important role in different parts of the body.
    • Polysaccharides can be classified as either storage or structural.
    • Storage polysaccharides include starch and glycogen, which are used to store energy.
    • Structural polysaccharides include cellulose, which provides structural support.
    • Chondroitin, keratan, dermatan, heparin, heparan, and hyaluronic acid are examples of polysaccharides with unique functions.
    • Chondroitin is found in heart valves, cells, eye, and skin.
    • Keratan is found in aorta.
    • Dermatan is found in connective tissue.
    • Heparan is a component of cell membranes.
    • Heparin is a protective and supportive polysaccharide used in medicine.
    • Hyaluronic acid is found in cartilage, acting as a shock absorber.
    • All these polysaccharides have a core protein that is covalently attached to linear carbohydrate chains.
    • Dermatan sulfate is not a good lubricant leading to age-related pains.
    • An amino group is usually acetylated, sometimes sulphated.

    Polysaccharides

    • Agar is a polysaccharide isolated from marine red algae.
    • All glycosaminoglycans (GAGs) except hyaluronic acid and heparin are found covalently attached to protein to form proteoglycans.
    • Proteoglycans are major components of cartilage, tendons, skin, bone, and other connective tissues.
    • The branch points in amylopectin occur once every 30 linkages.
    • Amylopectin is the outer, highly branched layer of starch.
    • Amylopectin is hydrolyzed by inulinase in plants.
    • Amylopectin is the most abundant natural polymer found in the world.
    • Amylopectin is found in the cell walls of nearly all plants.
    • Cellulose is formed of β-glucose units.
    • Cellulose has no dietary importance in humans.

    Polysaccharides (Glycans)

    • Polysaccharides are classified into homopolysaccharides and heteropolysaccharides.
    • Homopolysaccharides consist of only one type of monosaccharide.
    • Homopolysaccharides are also called homoglycans.
    • Heteropolysaccharides consist of more than one type of monosaccharide.
    • Heteropolysaccharides are also called heteroglycans.
    • Homopolysaccharides serve as intracellular energy stores.
    • Homopolysaccharides are also found in structural components like joints and bones.
    • Heteropolysaccharides are predominantly found as extracellular glycosaminoglycans (GAGs).
    • When the body is fasting, homopolysaccharides can be broken down to produce glucose to maintain blood glucose levels.
    • Homopolysaccharides can also be used to determine the glomerular filtration rate.
    • Membrane-bound glycoproteins, such as blood group antigens, are linked to the presence of homopolysaccharides.
    • The ABO blood grouping system is based on the antigenic differences determined by the type of glycoprotein present on the surface of red blood cells.

    Polysaccharides

    • Polysaccharides are complex carbohydrates composed of multiple monosaccharide units linked together.
    • They are classified into homopolysaccharides and heteropolysaccharides based on the type of monosaccharide units present.
    • Homopolysaccharides (homoglycans) contain only one type of monosaccharide, while heteropolysaccharides (heteroglycans) contain more than one type of monosaccharide.

    Homopolysaccharides

    • Examples of homopolysaccharides include starch, glycogen, dextran, dextrin, inulin, and cellulose.
    • Starch and glycogen are storage polysaccharides found in plants and animals, respectively.
    • Dextran and dextrin are branched polysaccharides used in various industrial processes.
    • Inulin is a fructan found in plants, primarily in roots and tubers.
    • Cellulose is the most abundant natural polymer found in the cell walls of nearly all plants.

    Heteropolysaccharides

    • Examples of heteropolysaccharides include glycosaminoglycans, agar, and proteoglycans.
    • Glycosaminoglycans (GAGs) are a family of linear polysaccharides that play important roles in various biological processes, including structural support, lubrication, and anticoagulation.
    • Agar is a polysaccharide extracted from red algae used as a gelling agent in various industries.
    • Proteoglycans are large macromolecules composed of a core protein covalently linked to one or more GAG chains.

    Key Facts

    • Cellulose is highly resistant to hydrolysis by acid and digestive tract amylase due to its β-glucose units.
    • Humans lack the enzyme inulinase, making inulin indigestible.
    • Hyaluronic acid is a major component of glycosaminoglycans and acts as a lubricant and anticoagulant.
    • The structure of polysaccharides is crucial for their function and biological activity.

    Glycoproteins

    • Consist of oligosaccharide chains attached to proteins
    • Chains are attached to proteins via:
      • Hydroxyl groups of serine and threonine residues (O-glycosidic bond)
      • Amide nitrogen of asparagine (N-glycosidic bond)

    Polysaccharides (Glycans)

    • Types include:
      • Dextran
      • Dextrin
      • Agar
      • Inulin
      • Starch
      • Glycogen (animal starch)

    Starch

    • Composed of α-D glucose units (glucosan)
    • Amylose: inner linear non-branching layer of starch, most common storage polysaccharide in plants
    • Amylopectin: highly branched outer layer of starch

    Glycogen (Animal Starch)

    • Composed of α-glucose units (glucosan)
    • Highly branched structure
    • Major form of storage polysaccharides in animals and the human body
    • Some animals secrete cellulase (β-glucosidase) which can hydrolyze cellulose

    Dextrin

    • α-glucose units (glucosan)

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