Biochemistry - Protein and Carbohydrates Quiz
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Questions and Answers

What condition is associated with protein malnutrition and results in negative nitrogen balance?

  • Marasmus
  • Pellegra
  • Kwashiorkor (correct)
  • Cachexia

    • Which specialized product is synthesized from glycine that is essential for muscle energy storage?

  • Creatine (correct)
  • Hemoglobin
  • Glutathione
  • Collagen

    • What is the consequence of a deficiency in phenylalanine hydroxylase?

  • Phenylketonuria (PKU) (correct)
  • Skeletal abnormalities
  • Disruption of amino acid absorption
  • Tyrosine excess

    • Which of the following is a neurotransmitter synthesized from glutamic acid?

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

    Which of the following products is synthesized from methionine and serves as a methyl donor?

    <p>SAM (S-adenosyl methionine)</p> Signup and view all the answers

    What structure characterizes L-sugars?

    <p>Hydroxyl group on the left side of the penultimate carbon atom</p> Signup and view all the answers

    Which of the following is an example of a ketotetrose?

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

    Which classification does not accurately describe aldoses?

    <p>Aldotetroses (C2)</p> Signup and view all the answers

    What type of isomerism do aldose-ketose pairs illustrate?

    <p>Functional group isomerism</p> Signup and view all the answers

    Which monosaccharide is a component of RNA?

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

    Which statement about D-glucose is false?

    <p>It is exclusive to animal cells.</p> Signup and view all the answers

    Which of the following is a type of pentose?

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

    What is true about structural isomers?

    <p>They have the same molecular formula but different structural formulas</p> Signup and view all the answers

    Which of the following amino acids is considered essential?

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

    What characterizes semi-essential or half-essential amino acids?

    <p>They are only produced in the body during specific conditions.</p> Signup and view all the answers

    Which of the following proteins is considered to have a high biological value?

    <p>Milk protein</p> Signup and view all the answers

    Which of the following statements is true regarding hydrophilic amino acids?

    <p>They contain O or N atoms in their side chains.</p> Signup and view all the answers

    What type of nitrogen balance is observed when nitrogen loss exceeds nitrogen incorporation?

    <p>Negative nitrogen balance</p> Signup and view all the answers

    Which of the following amino acids is classified as hydrophobic?

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

    What is the main role of hydrophobic amino acids in proteins?

    <p>To be located in the interior of the protein, away from water.</p> Signup and view all the answers

    Which of the following amino acids has a negatively charged side chain at physiological pH?

    <p>Glutamic acid</p> Signup and view all the answers

    What product is formed when glucose undergoes oxidation?

    <p>Glucuronic acid</p> Signup and view all the answers

    Which of the following is a sugar alcohol derived from glucose?

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

    What type of monosaccharide derivative is formed when a hydroxyl group is replaced by a hydrogen atom?

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

    Which of the following is a significant component of riboflavin?

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

    Which sugar derivative contains an amino group replacing a hydroxyl group?

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

    Which type of ester is formed from the hydroxyl groups of monosaccharides?

    <p>Phosphate esters</p> Signup and view all the answers

    What characterizes glycosides?

    <p>Condensation of the anomeric carbon with non-carbohydrate compounds</p> Signup and view all the answers

    What is the role of aminosugars in biology?

    <p>They contribute to glycosaminoglycans and are found in antibiotics</p> Signup and view all the answers

    What is the primary role of glycosaminoglycans (GAGs) in the extracellular matrix?

    <p>To produce a gel-like matrix</p> Signup and view all the answers

    Which glycosaminoglycan is recognized for its role in wound repair?

    <p>Hyaluronic acid</p> Signup and view all the answers

    Which of the following GAGs is known for maintaining corneal transparency?

    <p>Keratan sulfate</p> Signup and view all the answers

    How do glycosaminoglycans (GAGs) contribute to the compressibility of cartilage?

    <p>By creating a complex structure with various GAGs</p> Signup and view all the answers

    Which GAG is classified as a sulfate-containing heteropolysaccharide?

    <p>Chondroitin sulfate</p> Signup and view all the answers

    What function do heparan sulfate proteoglycans have in the cellular context?

    <p>They are crucial for cell-cell interactions</p> Signup and view all the answers

    Which property of GAGs allows them to attract water molecules?

    <p>Highly polar structure</p> Signup and view all the answers

    What is one of the functions of heparin in the bloodstream?

    <p>Preventing thrombus formation</p> Signup and view all the answers

    What is a primary characteristic of cis fatty acids?

    <p>They commonly occur in nature.</p> Signup and view all the answers

    Which of the following is classified as an essential fatty acid?

    <p>Arachidonic acid</p> Signup and view all the answers

    What happens as a result of deficiency in essential fatty acids?

    <p>Impaired growth in infants</p> Signup and view all the answers

    Which physical state do saturated fatty acids typically have at room temperature?

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

    What type of lipids are phospholipids?

    <p>Complex lipids</p> Signup and view all the answers

    What is the structural arrangement of trans fatty acids?

    <p>Hydrogens on opposite sides of the double bond</p> Signup and view all the answers

    Which fatty acids are primarily derived from dietary sources related to PUFA?

    <p>Linolenic and linoleic acids</p> Signup and view all the answers

    What are TAGs composed of?

    <p>Three fatty acids and glycerol</p> Signup and view all the answers

    Study Notes

    Protein Chemistry

    • Proteins are composed of a large number of amino acids linked together by peptide bonds.
    • Proteins have amphoteric properties.
    • Each protein has an isoelectric point (pI) at which the number of ionized negatively charged carboxyl groups equals the number of positively charged amino groups.
    • Proteins are classified as simple, compound, or derived.
    • Simple proteins are hydrolyzed to amino acids only. Example: Albumin and globulin in plasma and milk. Scleroproteins like keratin (skin), collagen (tendons, ligaments, connective tissue, bone, cartilage)
    • Compound proteins are hydrolyzed to amino acids and a prosthetic group. Examples of compound proteins:
      • Phosphoproteins: Milk casein
      • Lipoproteins: The form of lipid in blood circulation. Blood group antigens on red blood cells. Immunoglobulins (antibodies) in plasma. Proteoglycans attached to glycosaminoglycans in extracellular matrix of connective tissues. Metalloproteins containing iron (Fe).
    • Derived proteins are produced by hydrolysis of simple or conjugated lipids. Examples: fatty acids, alcohols, steroids, carotenoids, fat-soluble vitamins (A, D, E, K). -Hemoglobin is a tetramer composed of four polypeptide chains, two identical alpha (α) chains and two identical beta (β) chains -Myoglobin is an oxygen storage protein found mainly in muscle tissue. Composed of a single polypeptide chain.

    Protein Structure

    • Primary structure: The sequence of amino acids in a polypeptide chain. -Not affected by denaturation.
    • Secondary structure: Coiling or folding of the primary structure. Common types are alpha-helices and beta-sheets. -Held together by hydrogen bonds.
    • Tertiary structure: The three-dimensional arrangement of the polypeptide chain. -Determined by hydrophobic interactions, electrostatic forces (ionic bonds), and hydrogen bonds. -Either fibrous (insoluble in water) or globular (soluble in water).
    • Quaternary structure: The arrangement of multiple polypeptide chains in a protein. -Held together by non-covalent interactions, and is affected by denaturation.
    • Examples: hemoglobin, myoglobin.

    Denaturation

    • Denaturation is the change in the native state of a protein. -Rupture of weak bonds without altering primary structure. Common causes: - Physical: high pressure, high temperature, ionizing radiation (X-ray, UV), shaking (agitation), repeated freezing and thawing - Chemical: strong acids, strong bases, alcohol, heavy metals (like Pb2+, Ag2+, and Cu2+ etc), organic solvents, urea
      • It can lead to a change in physical, chemical, and biological properties of proteins.
      • It can be reversible in some conditions.

    Molecular Chaperones

    • Unfolded proteins are toxic to the cell due to their tendency to form large aggregates.
    • Machinery for safe protein folding is critical to cell function.
    • Chaperones are a class of proteins that facilitate successful protein folding. An energy-consuming process.

    Amino Acids

    • Building blocks of proteins.
    • Classified as neutral, acidic, and basic based on their chemical properties.
      • Hydroxyl containing amino acids: Serine, Theronine
      • Sulphate containing amino acids: Cysteine, Methionine
      • Neutral amino acids: Glycine, Alanine
      • Acidic amino acids: Aspartic acid, Glutamic acid
      • Basic amino acids: Lysine, arginine, histidine
    • Classified as hydrophilic or hydrophobic according to their interaction with water. -Hydrophobic: Phenylalanine, Tyrosine, Tryptophan, Valine, leucine and isoleucine. -Hydrophilic: Contain O or N atoms, some charged at physiological pH. Acidic amino acids (aspartic and glutamic acids) are negatively charged. Basic amino acids (lysine, arginine, and histidine) are positively charged.

    Protein functions

    • Proteins perform diverse roles; Examples are in:
      • Transport, like hemoglobin which carries oxygen.
      • Support, as in collagen.
      • Enzymes, like those that speed up metabolic reactions.
      • Hormones, like insulin which regulates blood sugar levels.

    Amino Acid Conversion to Specialized Products

    • Amino acids serve as precursors for specialized products in the body. Examples include:
      • Glycogen and Cellulose.
      • Neurotransmitters like melatonin and serotonin.
      • Hormones (e.g., thyroid hormones, epinephrine). -Pigments (e.g., melanin).
    • The conversion of amino acids into specialized products can be affected by genetic and nutritional factors.

    Nitrogen Balance

    • Nitrogen balance is a measure of the balance between the amount of nitrogen consumed and excreted. -Negative nitrogen balance: Nitrogen loss exceeds absorption, occurs during conditions like starvation, malnutrition, and injury.
    • Positive nitrogen balance: Nitrogen absorption exceeds excretion, occurs during growth and pregnancy.

    Carbohydrates

    • Chemical nature: polyhydroxyalcohols with a functional aldehyde or keto group (e.g., glucose, fructose).
    • Classification: Monosaccharides (single sugar units), Disaccharides (two sugar units), Oligosaccharides (a few sugar units), Polysaccharides (>10 sugar units). Examples include:
      • Glucose, Fructose, Galactose, Maltose, Sucrose, Lactose, Starch, Glycogen, Cellulose.
    • Biomedical importance: Provide energy, storage, structure (cell membranes), and communication.
    • Monosaccharide classification by number of carbon atoms, functional groups (aldose/ketose).
    • Important derivatives: Sugar acids (e.g., glucuronic acid), sugar alcohols (e.g., sorbitol), deoxy-sugars (e.g., deoxyribose), aminosugars (e.g., glucosamine).
    • Glycosides and ester formation.

    Lipids

    • Definition: Organic compounds that are esters of fatty acids or substances associated with them. Insoluble in water but soluble in fat solvents.
      • Classification: Simple, compound (or conjugated), and derived.
    • Fatty acids: Classified as saturated (no double bonds), monounsaturated (one double bond), and polyunsaturated (more than one double bond) -Examples: Stearic acid, oleic acid, linoleic acid.
    • Simple Lipids:
      • Triacylglycerols: Esters of three fatty acids and glycerol, stored in adipose tissue.
      • Waxes: Esters of fatty acids and long chain alcohols.
    • Compound Lipids:
      • Phospholipids: Lipids containing a phosphoric acid residue; Important for cell membranes and emulsifying factors.
        • Glycerophospholipids and sphingomyelin.
      • Glycolipids: Lipids containing carbohydrates; Important components of cell membranes.
      • Proteolipids: Lipids containing proteins; Water insoluble.
    • Derived lipids: Products of hydrolysis of simple or compound lipids. -Fatty acids, alcohols, steroids (e.g., cholesterol, bile acids), carotenoids, fat-soluble vitamins (A, D, E, K).

    Cholesterol

    • An important steroid in animals.
    • Can be converted into bile acids, bile salts, or steroid hormones.
    • Can be oxidized to 7-dehydrocholesterol converts to vitamin D3 by ultraviolet (UV) light.
    • Functions include precursor of steroid hormones, component of cell membranes, precursor of vitamin D.

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    Protein Chemistry Lectures (PDF)

    Description

    Test your knowledge on key concepts of biochemistry related to protein malnutrition, neurotransmitters, and sugar classifications. This quiz covers various biochemical compounds and their significance in the human body. Challenge yourself to understand the intricate relationships between amino acids and carbohydrates.

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