Hormone Synthesis and Steroid Hormones
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Hormone Synthesis and Steroid Hormones

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Questions and Answers

What is created when the signal sequence is removed from the preprohormone?

  • A messenger RNA
  • A peptide chain
  • An inactive prohormone (correct)
  • An active prohormone

    • Where does the preprohormone get directed after undergoing translation by ribosomes?

  • Golgi complex
  • Nucleus
  • Cytoplasm
  • Endoplasmic reticulum (ER) (correct)

    • What is the function of the enzymes in the endoplasmic reticulum (ER) during prohormone processing?

  • To chop off the signal sequence (correct)
  • To synthesize preprohormones
  • To create active hormones from prohormones
  • To package hormones into vesicles

    • Which hormone is primarily responsible for regulating circadian rhythms?

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

    What is the role of ribosomes in the synthesis of hormones?

    <p>Translating mRNA into peptide chains</p> Signup and view all the answers

    What structure is responsible for packaging the prohormone after it has exited the ER?

    <p>Golgi complex</p> Signup and view all the answers

    Which gland is responsible for the secretion of catecholamines?

    <p>Adrenal medulla</p> Signup and view all the answers

    What is the primary target of vasopressin (ADH)?

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

    What is the state of the prohormone after it leaves the endoplasmic reticulum but before it reaches the Golgi complex?

    <p>It is an inactive prohormone</p> Signup and view all the answers

    Which of the following hormones does not stimulate growth in tissues?

    <p>Corticotropin (ACTH)</p> Signup and view all the answers

    In which cellular component does the initial translation of the hormone occur?

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

    What is the first step in the synthesis of a prohormone?

    <p>Translation of mRNA into a preprohormone</p> Signup and view all the answers

    Which hormone is secreted by the anterior pituitary gland to initiate milk production?

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

    After enzymes process the prohormone, what pathway does it generally take?

    <p>Through the Golgi complex for packaging</p> Signup and view all the answers

    Which of the following hormones is derived from tryptophan?

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

    What is the initial structure formed before a prohormone is processed into active peptides?

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

    During the processing of a prohormone, which organelle is responsible for bud formation of secretory vesicles?

    <p>Golgi complex</p> Signup and view all the answers

    What signal triggers the release of contents from a secretory vesicle?

    <p>Release signal</p> Signup and view all the answers

    After the prohormone passes through the Golgi complex, what occurs next?

    <p>It is chopped into active peptides.</p> Signup and view all the answers

    What happens to the peptide fragments generated during prohormone processing?

    <p>They are released into the extracellular fluid.</p> Signup and view all the answers

    What role does mRNA play in the synthesis of a preprohormone?

    <p>It binds amino acids into a peptide chain.</p> Signup and view all the answers

    Where do the contents of secretory vesicles go after exocytosis?

    <p>Into the extracellular space</p> Signup and view all the answers

    What are the end products of prohormone processing in the Golgi complex?

    <p>Active peptides and fragments</p> Signup and view all the answers

    What does the term 'exocytosis' refer to in the context of secretory vesicles?

    <p>The release of contents into extracellular space</p> Signup and view all the answers

    Which of the following is NOT involved in the synthesis of a preprohormone?

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

    What role does the signal sequence play during the transport of proteins into the endoplasmic reticulum?

    <p>It directs the chain into the ER lumen.</p> Signup and view all the answers

    What occurs to the signal sequence once the prohormone is in the endoplasmic reticulum?

    <p>It is chopped off by enzymes.</p> Signup and view all the answers

    After the prohormone leaves the endoplasmic reticulum, where does it pass through next?

    <p>The Golgi complex.</p> Signup and view all the answers

    What happens to the prohormone during its processing in the Golgi complex?

    <p>It is transformed into an active hormone.</p> Signup and view all the answers

    What mechanism is used by the secretory vesicle to release its contents into the extracellular space?

    <p>Exocytosis.</p> Signup and view all the answers

    After the Golgi complex processes the prohormone, what are the components that are typically produced?

    <p>Active peptides and additional peptide fragments.</p> Signup and view all the answers

    Which part of the cell is primarily responsible for processing and packaging the prohormone?

    <p>Golgi complex.</p> Signup and view all the answers

    What is the immediate fate of the prohormone upon entering the endoplasmic reticulum?

    <p>It undergoes cleavage of the signal sequence.</p> Signup and view all the answers

    What type of molecule serves as a precursor that is cleaved into active hormones in the Golgi complex?

    <p>Prohormones.</p> Signup and view all the answers

    What is released into the extracellular fluid (ECF) as the final product of this processing pathway?

    <p>Active hormone.</p> Signup and view all the answers

    What distinguishes steroid hormones from peptide hormones in terms of their synthesis?

    <p>Steroid hormones are made only as needed.</p> Signup and view all the answers

    Where are steroid hormone receptors primarily located?

    <p>In the cytoplasm or nucleus.</p> Signup and view all the answers

    What role do carrier proteins play for steroid hormones in the bloodstream?

    <p>They extend the half-life of steroid hormones.</p> Signup and view all the answers

    Which statement about the action of steroid hormones is true?

    <p>Steroid hormones can activate or repress gene expression.</p> Signup and view all the answers

    What is a characteristic feature of steroid hormones in terms of their transportation in the blood?

    <p>They require specific transport proteins for stability.</p> Signup and view all the answers

    What is the result of binding a steroid hormone to a nongenomic membrane receptor?

    <p>Rapid cellular responses through secondary messenger systems.</p> Signup and view all the answers

    In what way do steroid hormones differ from most peptide hormones regarding their cellular effects?

    <p>Steroid hormones usually result in slower, genomic responses.</p> Signup and view all the answers

    How do peptide hormones generally travel in the bloodstream?

    <p>They circulate freely without the need for carriers.</p> Signup and view all the answers

    What happens when steroid hormones bind to cytoplasmic receptors?

    <p>They initiate transcription of specific genes.</p> Signup and view all the answers

    Which statement accurately describes the half-life of steroid hormones compared to peptide hormones?

    <p>Steroid hormones have a longer half-life than peptide hormones.</p> Signup and view all the answers

    Study Notes

    Hormone Synthesis

    • mRNA on ribosomes binds amino acids into a peptide chain called a preprohormone.
    • The chain is directed into the ER lumen by a signal sequence of amino acids.
    • Enzymes in the ER chop off the signal sequence, creating an inactive prohormone.
    • The prohormone passes from the ER through the Golgi complex.
    • Secretory vesicles containing enzymes and prohormone bud off the Golgi.
    • The enzymes chop the prohormone into one or more active peptides plus additional peptide fragments.
    • The secretory vesicle releases its contents by exocytosis into the extracellular space.

    Steroid Hormones

    • Steroid hormones are made only in a few organs: adrenal glands and gonads.
    • Steroid hormones bind carrier proteins in blood, which gives them a longer half-life
    • Steroid hormones can bind to cytoplasmic or nuclear receptors, leading to genomic effects that activate or repress genes, which is slower acting.
    • Steroid hormones can also bind to cell membrane receptors for rapid nongenomic responses.

    Hormone Groups

    • Amino Acid-Derived: derived from one of two amino acids, tryptophan and tyrosine.
      • Examples: melatonin, catecholamines (epinephrine, dopamine), and thyroid hormones.
    • Steroid: Cholesterol-derived
      • Made only in a few organs: adrenal glands and gonads.
      • Lipophilic, they easily cross membranes.
      • Made as needed, not stored.
      • Bind carrier proteins in blood.
      • Longer half-life.
      • Cytoplasmic or nuclear receptors.
      • Slower acting.
      • Cell membrane receptors.
      • Nongenomic responses.
    • Peptide: Composed of amino acid chains.
      • Most hormones are peptides, including those from the anterior pituitary.

    Neurohormones

    • Adrenal medulla: Catecholamines (epinephrine, norepinephrine).
    • Hypothalamus: TRH, CRH, GHRH, GnRH, dopamine (PIH), somatostatin

    Neurohormones

    • The pituitary gland is two glands fused as one.
    • The posterior pituitary is neural tissue and secretes two neurohormones: vasopressin (antidiuretic hormone or ADH) and oxytocin.

    Major Hormone Groups

    • Pineal Gland: Melatonin: Main effect on circadian rhythms, immune function, and antioxidant actions; Targets - brain and other tissues.
    • Hypothalamus (Neurohormones): Trophic Hormones: Regulate other glands; Targets - Anterior pituitary.
    • Posterior Pituitary (Neurohormones): Oxytocin: Targets - breast and uterus. Main effect on milk ejection, labor and delivery, and behavior.
    • Vasopressin (ADH):* Targets - kidney. Main effect on water reabsorption.
    • Anterior Pituitary (Glandular Hormones):
    • Prolactin:* Targets - breast and liver. Main effect on milk production.
    • Growth Hormone (somatotropin):* Targets - many tissues. Main effect on growth factor secretion, growth, and metabolism.
    • Corticotropin (ACTH):* Targets - adrenal cortex. Main effect on cortisol release.
    • Thyrotropin (TSH):* Targets - thyroid gland. Main effect on thyroid hormone synthesis
    • Follicle-stimulating hormone (FSH):* Targets - gonads. Main effect on egg or sperm production; sex hormone production.
    • Luteinizing hormone (LH):* Targets - gonads. Main effect on sex hormone production; egg or sperm production.

    Hormone Groups - Abbreviation Key

    • G: Gland
    • C: Endocrine Cells
    • N: Neuron
    • P: Peptide
    • S: Steroid
    • A: Amino Acid-Derived

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    Related Documents

    Endocrine System Lecture Notes PDF

    Description

    This quiz covers the synthesis of hormones, detailing the process from mRNA binding to the exocytosis of active peptides. It also explores the production and function of steroid hormones, including their interaction with receptors. Test your knowledge on these essential biochemical processes.

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