Introduction to Hemoglobin

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Questions and Answers

What is the primary location where most haemoglobin synthesis occurs before the reticulocyte stage?

  • Bone marrow
  • Cytoplasm and mitochondria (correct)
  • Lung tissue
  • Liver

What type of structure is haemoglobin considered to be?

  • Prototypical oligomer
  • Simple dimer
  • Heterodimeric tetramer (correct)
  • Monomeric protein

Which chains are essential for haemoglobin synthesis beyond the embryonic stage?

  • α chains (correct)
  • γ chains only
  • δ chains
  • β chains only

What is the role of ferrochelatase in the synthesis of haem?

<p>It incorporates iron into haem (B)</p> Signup and view all the answers

Where is haem located in relation to globin chains in haemoglobin?

<p>Toward the periphery of the globin chains (B)</p> Signup and view all the answers

What is the significance of different iron states in haem?

<p>They can affect the final function of the haem molecule (A)</p> Signup and view all the answers

Which statement about haem synthesis is false?

<p>Haem is synthesized primarily in the liver (A)</p> Signup and view all the answers

What other component is necessary for the effective incorporation of iron in haem?

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

Which of the following does not represent a stage of haemoglobin maturation?

<p>Mature lymphocyte stage (D)</p> Signup and view all the answers

What aspect of haemoglobin is primarily altered during its maturation?

<p>The conformation of the protein (B)</p> Signup and view all the answers

What is the primary function of red blood cells in relation to haemoglobin?

<p>Carry O2 from lungs to tissues and CO2 back to lungs (D)</p> Signup and view all the answers

Which measurement is NOT included in the principal haemoglobin measurements reported in the Full Blood Count?

<p>Mean Cell Volume (MCV) (D)</p> Signup and view all the answers

What is the basic structural configuration of haemoglobin?

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

Which of the following is a correct statement about the composition of the haemoglobin molecule?

<p>It is composed of two alpha-like globin chains and two non-alpha globin chains. (B)</p> Signup and view all the answers

During haemoglobin synthesis, which of these compounds is the starting material to form haem?

<p>Glycine + Succinyl CoA (C)</p> Signup and view all the answers

What is the range for Mean Cell Haemoglobin (MCH)?

<p>27 – 32 pg (D)</p> Signup and view all the answers

Which enzyme is responsible for converting protoporphyrinogen IX to protoporphyrin IX during haem synthesis?

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

What percentage of cytoplasmic protein in red blood cells is haemoglobin?

<p>98% (D)</p> Signup and view all the answers

What is the role of ferrochelatase in haemoglobin synthesis?

<p>Add iron to protoporphyrin (D)</p> Signup and view all the answers

In the process of haemoglobin synthesis, which compound is produced alongside globin chains?

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

Flashcards

Haemoglobin

A complex protein found in red blood cells responsible for carrying oxygen to the tissues and carbon dioxide back to the lungs.

Haemoglobin synthesis

The process by which haemoglobin is made, involving a series of enzymatic steps to synthesize both the globin chains and the heme molecule.

Haemoglobin structure

A protein molecule composed of four polypeptide chains, two alpha and two beta chains, each with a heme group.

Porphyrias

A group of inherited disorders caused by defects in the synthesis of porphyrins, leading to a buildup of these molecules in the body, affecting various organs and systems.

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Haem group

A special molecule consisting of a porphyrin ring complexed with an iron atom.

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Haemoglobin measurement

The amount of haemoglobin present in a given volume of blood.

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Mean Cell Haemoglobin (MCH)

The average amount of haemoglobin in each red blood cell.

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Mean Cell Haemoglobin Concentration (MCHC)

The average concentration of haemoglobin within a red blood cell.

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Hb

The main protein in red blood cells, responsible for carrying oxygen.

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Fetal haemoglobin

A type of haemoglobin formed during the development of red blood cells before the nucleus is removed.

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Haemoglobin synthesis location

The majority of haemoglobin is produced in the reticulocyte stage of red blood cell development.

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Haemoglobin synthesis locations

The production of haemoglobin occurs both in the cytoplasm of the cell, on ribosomes, and within the mitochondria.

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Ferrochelatase function

Ferrochelatase is the crucial enzyme responsible for incorporating iron into the haem molecule.

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Haem location within the globin chains

The haem molecule is situated at the periphery of the globin chains, not at the center.

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Iron state in haem

The iron atom at the center of haem can exist in various states, which are important for its function.

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Globin chain changes during development

Before the embryonic stage, different types of globin chains are present in haemoglobin.

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Alpha chain importance in haemoglobin

Alpha chains are essential for haemoglobin after the embryonic stage, meaning they are always present in mature haemoglobin.

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Haemoglobin subunit arrangement

Haemoglobin is a tetramer, meaning it consists of four subunits.

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Haemoglobin subunit composition

Haemoglobin is a heterodimer, meaning it is composed of two different types of subunits within its tetramer structure.

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Study Notes

Introduction to Haemoglobin

  • Red blood cells carry oxygen from the lungs to tissues and carbon dioxide back to the lungs
  • About 98% of the cytoplasm's protein is haemoglobin (Hb)
  • 65% of Hb is produced before the cell nucleus is expelled
  • Haemoglobin is a metalloprotein

Learning Objectives

  • Describe the formation of the haemoglobin molecule
  • Describe the basic structure of haemoglobin
  • Identify the consequences of specific haemoglobin synthesis defects
  • Identify haemoglobin measurements within a full blood count (FBC)

Haemoglobin Measurements in FBC

  • Haemoglobin (Hb)
  • Mean Cell Haemoglobin (MCH): range 27-32 pg
  • Mean Cell Haemoglobin Concentration (MCHC): range 315-345 g/L

Basic Structure of Haemoglobin

  • Haemoglobin is a heterodimeric tetramer
  • It consists of four globin chains (two alpha and two beta)
  • It also contains a haem group with an iron molecule

Haemoglobin Synthesis

  • Haem synthesis involves the chemical reaction of glycine and succinyl CoA, catalysed by ALA synthase
  • ALA synthase generates amino-laevulinic acid that is used in the subsequent synthesis stages of porphyrin and haem
  • The synthesis is conducted in the cytoplasm and mitochondria
  • Iron is incorporated into the haem group by ferrochelatase
  • Haem is located towards the periphery of the globin chains

Porphyrias

  • Porphyrias are a group of genetic disorders caused by defects in the haem synthesis pathway
  • Defects can lead to the accumulation of specific porphyrin precursors in erythrocytes and other tissues

Haem

  • Iron is chelated into protoporphyrin IX to form the final haem molecule
  • The iron ion can exist in different states while in the haem molecule

Summary

  • Most haemoglobin synthesis happens before the reticulocyte stage of maturation
  • Mature haemoglobin needs the alpha and beta globin chains
  • Haemoglobin synthesis occurs in the cytoplasm (ribosomes) and mitochondria
  • Ferrochelatase puts iron into haem subunits
  • Haem parts are located towards the outside of the globin chains

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Related Documents

Haemoglobin Synthesis Lecture Notes PDF

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