Hemoglobin Structure and Formation
13 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of 2,3-diphosphoglycerate (DPG) in hemoglobin function?

  • It binds to the iron atom in the heme group, preventing oxidation to methemoglobin.
  • It promotes the binding of carbon monoxide to hemoglobin, leading to carbon monoxide poisoning.
  • It is a coenzyme involved in the synthesis of heme.
  • It stabilizes the quaternary structure of deoxyhemoglobin, enhancing oxygen release. (correct)

    • What causes a right shift in the oxygen dissociation curve of hemoglobin?

  • Increased affinity of hemoglobin for oxygen, resulting in increased oxygen delivery to tissues.
  • Increased pH and decreased concentration of 2,3-DPG.
  • Reduced affinity of hemoglobin for oxygen, resulting in enhanced oxygen delivery to tissues.
  • Decreased pH and increased concentration of 2,3-DPG. (correct)

    • Which statement accurately describes the structure of hemoglobin?

  • It is a tetrameric protein composed of two alpha and two beta subunits. (correct)
  • It is a single polypeptide chain with a single heme group.
  • It is a fibrous protein with a helical structure.
  • It is a globular protein that contains four heme groups, each binding to a single iron atom. (correct)

    • What is the effect of carbon monoxide (CO) on hemoglobin?

    <p>CO binds to the iron atom in heme, preventing oxygen binding and leading to carbon monoxide poisoning. (C)</p> Signup and view all the answers

    Which of the following is NOT a factor that influences the oxygen dissociation curve of hemoglobin?

    <p>The concentration of glucose in red blood cells. (D)</p> Signup and view all the answers

    Which of the following statements is TRUE regarding hemoglobin synthesis?

    <p>Protoporphyrin combines with ferrous iron (Fe2+) to form heme. (C)</p> Signup and view all the answers

    What is the main function of hemoglobin in the body?

    <p>To transport oxygen from the lungs to the tissues. (C)</p> Signup and view all the answers

    What is the difference between hemoglobin A (Hb A) and fetal hemoglobin (Hb F)?

    <p>Hb F has a higher affinity for oxygen than Hb A, making it more efficient at absorbing oxygen from the maternal circulation. (E)</p> Signup and view all the answers

    What effect does a higher pH have on the binding of oxygen to hemoglobin?

    <p>It promotes tighter binding of oxygen to hemoglobin. (A)</p> Signup and view all the answers

    Which of the following accurately describes hematocrit?

    <p>It is the volume percentage of red blood cells in a blood sample. (D)</p> Signup and view all the answers

    Which condition would likely cause a decrease in hematocrit levels?

    <p>A decrease in the number of red blood cells. (A)</p> Signup and view all the answers

    What is a common method for carrying out a hematocrit test?

    <p>Using a centrifuge with a microhematocrit tube. (B)</p> Signup and view all the answers

    What are the normal hematocrit ranges for females?

    <p>36 %–47 % (B)</p> Signup and view all the answers

    Flashcards

    Hemoglobin A (Hb A)

    Normal adult hemoglobin, made of four polypeptide chains (α2β2) and four heme groups.

    Protoporphyrin

    A molecule that combines with iron (Fe2+) to form heme, which colors it deep red.

    Oxygen Binding to Hemoglobin

    Binding of O2 causes a conformational change in hemoglobin structure, allowing transport.

    2,3-Diphosphoglycerate (DPG)

    A molecule that enhances oxygen release by stabilizing the deoxyhemoglobin structure.

    Signup and view all the flashcards

    Hemoglobin Synthesis

    Involves haem synthesis in mitochondria and globin chain synthesis on ribosomes, with Vitamin B6 as a coenzyme.

    Signup and view all the flashcards

    Oxygen Dissociation Curve - Right Shift

    Occurs when hemoglobin releases O2 more easily, usually due to high levels of CO2 or 2,3-DPG.

    Signup and view all the flashcards

    Methemoglobin

    Formed when Fe(II) in hemoglobin is oxidized to Fe(III), giving it a brown color.

    Signup and view all the flashcards

    Fetal Hemoglobin (Hb F)

    Has a higher affinity for O2 than adult hemoglobin, meaning it holds onto oxygen more tightly.

    Signup and view all the flashcards

    Bohr Effect

    Increased pH tightens oxygen binding; decreased pH allows easier release of oxygen from hemoglobin.

    Signup and view all the flashcards

    Hematocrit

    Volume percentage of red blood cells in a blood sample after centrifugation.

    Signup and view all the flashcards

    RBC volume fraction

    Also called erythrocyte volume fraction, it measures the proportion of blood occupied by red blood cells.

    Signup and view all the flashcards

    Normal hematocrit ranges

    Normal hematocrit values: Males 40%-54%, Females 36%-47%, Newborns 55%-68%.

    Signup and view all the flashcards

    Microhematocrit tube

    Capillary tube used to measure hematocrit; contains anticoagulant and measures RBC volume accurately.

    Signup and view all the flashcards

    Study Notes

    Hemoglobin Structure

    • Normal adult hemoglobin A (Hb A) consists of four polypeptide chains (α₂β₂).
    • Hb A also contains Hb F and Hb A₂.
    • Hb A has four heme groups.
    • The table shows the percentage of each hemoglobin type found in adult blood.
    Hemoglobin Type Structure Normal Percentage (%)
    Hb A α₂β₂ 96-98
    Hb F α₂γ₂ 0.5-0.8
    Hb A₂ α₂δ₂ 1.5-3.2

    Hemoglobin Formation

    • Hemoglobin is formed via a series of steps.
    • The first is combining 2 succinyl-CoA and 2 glycine.
    • This creates 4 pyrroles.
    • Protoporphyrin IX is then formed from the 4 pyrroles
    • Protoporphyrin IX and ferrous iron (Fe²⁺) combine to form heme.
    • Heme then combines with polypeptide chains (α or β) to create a hemoglobin chain.
    • Two α chains and two β chains combine to create hemoglobin A.

    Hemoglobin Structure (Detailed View)

    • Hemoglobin is a globular protein.
    • It has a quaternary structure formed by four polypeptide chains (globins) arranged in a tetramer (two α chains and two β chains).
    • Each globin chain has a heme group.
    • Heme contains an iron atom (Fe) which binds to oxygen.

    Hemoglobin Function

    • Carries oxygen from the lungs to the tissues.
    • Returns CO₂ from the tissues to the lungs.
    • Hemoglobin's oxygen-carrying capacity depends on several factors:
      • The presence of 2,3-diphosphoglycerate (DPG)
      • The pH level
      • The partial pressure of CO₂
      • Hemoglobin structure
    • When iron (Fe²⁺) is oxidized to iron (Fe³⁺), methemoglobin is formed (brown in color)
    • Carbon monoxide (CO) binds strongly to hemoglobin, preventing oxygen binding.

    Hemoglobin Synthesis

    • Hemoglobin synthesis occurs in the mitochondria.
    • Vitamin B₆ acts as a coenzyme in the reaction.
    • Iron is supplied by the circulation transferrin.
    • Globin chains are synthesized on ribosomes.
    • Protoporphyrin combines with ferrous iron (Fe²⁺) to form heme.
    • Four globin chains, each with a heme group, combine to form a hemoglobin molecule.

    Hematocrit

    • Hematocrit measures the percentage of red blood cells (RBCs) in a blood sample after centrifugation.
    • It is also referred to as packed cell volume (PCV) or erythrocyte volume fraction (EVF).
    • Normal ranges are different in males, females, and newborns.
    • It measures the viscosity of blood. The higher the hematocrit, the higher the viscosity.
    • A lower hematocrit may indicate anemia, while a higher hematocrit may indicate polycythemia
    • RBC or hemoglobin counts are less accurate than hematocrit measurements; measurement abnormalities in hematocrit show a larger error rate.

    Bohr Effect

    • A decrease in pH promotes the release of oxygen from hemoglobin.
    • An increase in pH promotes the binding of oxygen to hemoglobin.
    • The Bohr effect is due to the interaction between hydrogen ions (H⁺) and hemoglobin.
    • CO2 reacts with water creating carbonic acid (H₂CO₃) which dissociates into hydrogen ions and bicarbonate ions (HCO₃⁻).

    Other important notes and factors

    • Carbon monoxide (CO) is toxic because it binds more strongly to hemoglobin than oxygen, preventing oxygen from binding.
    • Certain drugs or toxins can oxidize the iron in hemoglobin to form methemoglobin. This alters hemoglobin function.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Hemoglobin (Structure, Function, and Synthesis) PDF

    Description

    This quiz explores the structure and formation of hemoglobin, focusing on its various types, including normal adult hemoglobin A and its formation process. Key concepts such as the polypeptide chains and heme production are covered in detail. Test your knowledge on the intricacies of this vital protein!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser