Amino Acids Classification Quiz
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Amino Acids Classification Quiz

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Questions and Answers

What is primarily responsible for the tertiary structure of a protein?

  • The arrangement of the amino acid sequence
  • The interactions between the R groups of amino acids (correct)
  • The hydrogen bonds between the backbone of the polypeptide
  • The peptide bonds between amino acids

    • Which type of bond is stronger in contributing to the tertiary structure of proteins?

  • Disulfide bonds (correct)
  • Hydrogen bonds
  • Hydrophobic interactions
  • Ionic bonds

    • What is the quaternary structure of a protein?

  • The arrangement of non-polar and polar amino acids
  • A single chain of amino acids folded into a specific shape
  • The sequence of amino acids in a polypeptide
  • The overall three-dimensional structure of multiple polypeptide chains (correct)

    • Which of the following is NOT a type of protein based on its function?

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

    Which protein acts as a transport protein for oxygen in the blood?

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

    Which of the following is an example of a storage protein?

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

    Which class of proteins helps in combating foreign substances in the body?

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

    Which of the following statements about hydrophobic interactions is true?

    <p>They help position hydrophobic amino acids in the interior of the protein.</p> Signup and view all the answers

    Which classification of amino acids has more amino groups than carboxylic groups?

    <p>Basic amino acids</p> Signup and view all the answers

    Which category of amino acids must be obtained through the diet?

    <p>Essential amino acids</p> Signup and view all the answers

    Which of the following is a pure ketogenic amino acid?

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

    Which classification of amino acids includes those that can convert into both glucose and ketone bodies?

    <p>Both glucogenic &amp; ketogenic amino acids</p> Signup and view all the answers

    Which of the following amino acids is classified as an imino acid?

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

    Which protein classification produces only amino acids upon hydrolysis?

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

    Which amino acid is an essential amino acid involved in various metabolic functions?

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

    What type of amino acids are responsible for producing glucose exclusively?

    <p>Glucogenic amino acids</p> Signup and view all the answers

    What type of groups does Coenzyme A transfer?

    <p>Acyl groups</p> Signup and view all the answers

    Which enzyme is associated with the cofactor Zn++?

    <p>Alcohol dehydrogenase</p> Signup and view all the answers

    What does NADP+ partially transfer?

    <p>Electrons (hydrogen atoms)</p> Signup and view all the answers

    Which of the following is an example of absolute specificity in enzymes?

    <p>Uricase and uric acid</p> Signup and view all the answers

    Which coenzyme is involved in transferring amino groups?

    <p>Pyridoxal phosphate</p> Signup and view all the answers

    What is the role of cofactors in enzymatic reactions?

    <p>To increase the rate of catalysis</p> Signup and view all the answers

    What type of ion is required as a cofactor by pyruvate phosphokinase?

    <p>Potassium ion (K+) and Magnesium ion (Mg++)</p> Signup and view all the answers

    Which enzyme uses Fe+++ or Fe++ as a cofactor?

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

    What is a key difference between enzymes and hormones regarding their site of action?

    <p>Hormones act at a site different from where they are produced.</p> Signup and view all the answers

    In terms of chemical nature, which of the following is classified as a polypeptide or protein hormone?

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

    Which of the following hormones bind to intranuclear receptors?

    <p>Steroid hormones</p> Signup and view all the answers

    What role does cAMP play in the mechanism of action of hormones with extracellular receptors?

    <p>It serves as a second messenger.</p> Signup and view all the answers

    Which type of hormone is known to have receptors located intracytoplasmically?

    <p>Steroid hormones</p> Signup and view all the answers

    How do hormones that utilize intracellular receptors generally function?

    <p>They influence gene transcription directly.</p> Signup and view all the answers

    Which category does melatonin belong to based on its chemical nature?

    <p>Amino acid derivatives</p> Signup and view all the answers

    What happens upon the binding of a hormone to its extracellular receptor?

    <p>It may activate adenylate cyclase.</p> Signup and view all the answers

    Which hormone specifically acts on muscle and liver, while another acts only on the liver?

    <p>Epinephrine and glucagon</p> Signup and view all the answers

    What is the final product of cAMP degradation by phosphodiesterase?

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

    What physiological effect does cAMP NOT stimulate?

    <p>Protein synthesis</p> Signup and view all the answers

    Which subunit of the G-protein dissociates to interact with adenylate cyclase?

    <p>α-GTP subunit</p> Signup and view all the answers

    What type of hormone primarily stimulates the thyroid gland?

    <p>Thyroid-stimulating hormone (TSH)</p> Signup and view all the answers

    Which of the following is a function of insulin in relation to cAMP?

    <p>Activates phosphodiesterase</p> Signup and view all the answers

    Which lobe of the pituitary gland is responsible for producing growth hormone?

    <p>Anterior lobe</p> Signup and view all the answers

    How does a neurotransmitter or hormone initiate G-protein action?

    <p>By causing a conformational change in the receptor</p> Signup and view all the answers

    Study Notes

    Amino Acids

    • 20 different amino acids are essential for human life.
    • 12 amino acids can be synthesized by the human body.
    • 8 essential amino acids must be obtained from food.
    • Amino acids are classified based on their chemical structure and nutritional requirements.
    • Chemical Classification:
      • Neutral Amino Acids: Contain an equal number of amino and carboxylic groups.
        • Aliphatic Amino Acids:
          • Glycine, Alanine, Valine, Isoleucine, Leucine
        • Hydroxy Amino Acids:
          • Serine, Threonine
        • Sulphur Amino Acids:
          • Cysteine, Cystine, Methionine
        • Aromatic Amino Acids:
          • Phenylalanine, Tyrosine, Tryptophan
      • Basic Amino Acids: Have more amino groups than carboxylic groups.
        • Histidine, Arginine, Lysine.
      • Acidic Amino Acids: Have more carboxylic groups than amino groups.
        • Glutamic acid, Aspartic acid.
      • Imino Acids: Contain an imino group (NH).
        • Proline, Hydroxyproline.
    • Nutritional Classification:
      • Essential Amino Acids:
        • Cannot be synthesized by the body.
        • Must be obtained from diet.
        • Deficiency can lead to diseases.
        • Examples: Valine, Leucine, Isoleucine, Histidine, Phenylalanine, Tryptophan, Threonine, Methionine.
      • Nonessential Amino Acids:
        • Synthesized in the body.
        • Not essential for dietary intake.
        • Includes all other amino acids not classified as essential.
    • Metabolic (Biological) Classification:
      • Based on the fate of amino acids in the body.
      • Glucogenic Amino Acids:
        • Converted into glucose.
        • All amino acids except leucine are glucogenic.
      • Ketogenic Amino Acids:
        • Converted into ketone bodies.
        • Examples: Leucine and lysine.
      • Both Glucogenic and Ketogenic:
        • Converted into both glucose and ketone bodies.
        • Examples: Tyrosine, Phenylalanine, Tryptophan, Isoleucine.

    Proteins

    • Definition: Polymers of amino acids linked by peptide bonds.
    • Classification of Proteins:
      • According to Peptide Bond Structure:
        • Simple Proteins:
          • Only produce amino acids on hydrolysis.
          • Examples:
            • Albumin: Found in egg white, serum, and milk.
            • Globulin: Found in egg white, serum, and milk.
            • Histones: Associated with nucleic acids (chromatin) and in the globin part of hemoglobin.
            • Scleroproteins (Albuminoids):
              • Keratin: Found in hair, nails, and dermis.
              • Elastin: Found in elastic tissues.
        • Conjugated Proteins:
          • Have a non-protein component called a prosthetic group.
          • Examples:
            • Phosphoproteins: Contain phosphate groups.
            • Lipoproteins: Contain lipids.
            • Glycoproteins: Contain carbohydrates.
            • Chromoproteins: Contain pigments.
            • Nucleoproteins: Contain nucleic acids.
      • According to Function:
        • Catalytic Proteins (Enzymes): Act as biochemical catalysts.
          • Examples: Glucokinase, Dehydrogenase, Transaminase.
        • Defense Proteins: Bind to foreign substances (like bacteria and viruses) to combat invasion.
          • Examples: Immunoglobulins.
        • Transport Proteins: Bind to small biomolecules and transport them.
          • Examples:
            • Hemoglobin: Transports oxygen.
            • Transferrin: Transports iron.
        • Storage Proteins: Bind and store small molecules for future use.
          • Examples:
            • Ferritin: Stores iron in the liver.
            • Myoglobin: Stores oxygen in muscles.
        • Nutrient Proteins: Important in early life, from embryo to infant.
          • Example: Casein in milk.
        • Regulatory Proteins: Regulate cellular and physiological activities.
          • Example: Insulin.

    Coenzymes in Group Transfer Reactions

    • Coenzymes are non-protein organic molecules that assist enzymes in their function.
    • They are often required for specific reactions.
    • Examples of Coenzymes in Group Transfer Reactions:
      • Nicotine Adenine Dinucleotide: NAD and NADP
        • Functions: Electron (hydrogen atom) carriers in redox reactions.
      • Flavin Adenine Dinucleotide: FAD
        • Function: Electron (hydrogen atom) carrier in redox reactions.
      • Coenzyme A: CoA
        • Function: Carries acyl groups.
      • Coenzyme Q: CoQ
        • Function: Electron (hydrogen atom) carrier in redox reactions.
      • Thiamine Pyrophosphate: Vitamin B1
        • Function: Handles aldehydes.
      • Pyridoxal Phosphate: Vitamin B6
        • Function: Handles amino groups.
      • Biotin:
        • Function: Carries carbon dioxide.
      • Cobamide Coenzymes: Vitamin B12
        • Function: Carries alkyl groups.

    Cofactors

    • Inorganic substances that are required for, or increase the rate of, catalysis.
    • Often metal ions.
    • Examples of Enzymes with Metal Ion Cofactors:
      • Carbonic Anhydrase: Zn++
      • Alcohol Dehydrogenase: Zn++
      • Cytochromes, Hemoglobin: Fe+++ or Fe++
      • Ferredoxin: Fe+++ or Fe++
      • Cytochrome Oxidase: Cu++ or Cu+
        • Pyruvate Phosphokinase: K+ and Mg++

    Enzyme Specificity

    • Enzymes are highly specific:
      • Absolute Specificity: Enzyme acts on only one substrate.
        • Examples: Uricase and uric acid, Urease and urea.
      • Relative Specificity: Enzyme acts on a group of similar compounds.
        • Often targets a specific bond or functional group.
      • Stereochemical Specificity: Enzyme distinguishes between stereoisomers.

    Hormonal Action:

    • Hormones are chemical messengers that regulate various bodily processes.

    • They differ from enzymes in their site of production and mode of action.

    • Classification of Hormones:

      • According to Chemical Nature:

        • Amino Acid Derivatives:
          • Thyroid hormones (T3 and T4)
          • Catecholamines (Epinephrine and norepinephrine)
          • Melatonin
        • Polypeptide or Protein Hormones:
          • Hypothalamic, pituitary, parathyroid, and pancreatic hormones.
        • Steroid Hormones:
          • Adrenocortical hormones
          • Calcitriol hormone

      • According to Location of Receptors:

        • Intracellular Receptors (Group I):
          • Intracytoplasmic Receptors: Steroid hormones.
          • Intranuclear Receptors: Thyroid hormones.
        • Extracellular Receptors (Group II):
          • Catecholamines, Glucagons, Calcitonin, Pituitary hormones.

    • Mechanisms of Hormone Action:

      • Group I: Hormones with Intracellular Receptors:

        • Lipophilic (fat-soluble) hormones diffuse through the plasma membrane.
        • Bind to high-affinity receptors in the target cell.
        • The hormone-receptor complex binds to specific regions of DNA called hormone response elements (HRE).
        • This activates gene transcription and mRNA production.
        • The mRNA translates to a specific protein (enzyme).
        • The new enzyme then activates the metabolic process.

      • Group II: Hormones with Extracellular Receptors:

        • Water-soluble hormones interact with plasma membrane receptors.
        • This interaction can activate or inactivate adenylate cyclase.
        • Activation of adenylate cyclase leads to cAMP (cyclic adenosine monophosphate) production from ATP.
        • cAMP is considered a second messenger.
        • cAMP activates protein kinase, which phosphorylates proteins and elicits physiological effects.

    • Examples of Hormones That Activate Adenylate Cyclase:

      • Epinephrine, Norepinephrine, Glucagon, Parathyroid Hormone, FSH, LH, ACTH, MSH.

    • Effects of cAMP Activation:

      • Stimulates glycogenolysis via phosphorylase activation.
      • Stimulates lipolysis via lipase activation.
      • Inhibits glycogenesis by inhibiting glycogen synthetase.

    • G-Proteins and Hormonal Action:

      • Hormones bind to the external face of the G-protein coupled receptor.
      • The receptor undergoes a conformational change, which is propagated to the G-protein binding site.
      • The G-protein binding site binds to the trimeric G-protein (αβγ), causing it to exchange bound GDP for GTP.
      • Exchange of GDP to GTP causes the G-protein to dissociate into α-GTP and βγ subunits.
      • The α-GTP subunit diffuses across the inner face of the plasma membrane and interacts with adenylate cyclase.
      • Adenylate cyclase becomes activated and converts ATP to cAMP as long as α-GTP is bound to it.
      • The α-subunit has GTPase activity and eventually hydrolyzes its bound GTP to GDP + Pi.
      • The α-subunit then dissociates from adenylate cyclase and diffuses back to re-associate with βγ to form an inactive molecule.

    Pituitary Hormones:

    • The pituitary gland is often referred to as the "master gland" of the endocrine system because it controls the functions of other endocrine glands.

    • It is located at the base of the brain and is connected to the hypothalamus by nerve fibers.

    • The pituitary gland has three sections:

      • Anterior Lobe (Adenohypophysis)
      • Intermediate Lobe (Pars Intermedia)
      • Posterior Lobe (Neurohypophysis)

    • **Hormones of the Anterior Lobe: **

      • Growth Hormone (GH)
      • Adrenocorticotropic Hormone (ACTH)
      • Thyroid Stimulating Hormone (TSH)
      • Follicle-Stimulating Hormone (FSH)
      • Luteinizing Hormone (LH)
      • Prolactin

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    Test your knowledge on amino acids with this quiz! Explore the essential amino acids, their classifications, and the differences between them. Discover how these vital compounds contribute to human health and nutrition.

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