hemoglobin

Examples of hemoglobin in the following topics:

• Oxygen Transport

  • Hemoglobin is a protein found in red blood cells (also called erythrocytes).
  • This also means that the approximate carrying capacity for oxygen in hemoglobin has been reached and excess oxygen won't go into hemoglobin.
  • Rightward shifts indicate a decreased affinity for the binding of hemoglobin, so that less oxygen binds to hemoglobin, and more oxygen is unloaded from it into the tissues.
  • Leftward shifts indicate an increased affinity for the binding of hemoglobin, so that more oxygen binds to hemoglobin, but less oxygen is unloaded from it into the tissues.
  • The oxygen–hemoglobin dissociation curve plots the percent hemoglobin saturation (y-axis) against the partial pressure of oxygen in the blood (PO2).

• Transport of Oxygen in the Blood

  • The majority of oxygen in the body is transported by hemoglobin, which is found inside red blood cells.
  • Most oxygen, 98.5 percent, is bound to a protein called hemoglobin and carried to the tissues.
  • Hemoglobin is made up of four symmetrical subunits and four heme groups.
  • It is the iron in hemoglobin that gives blood its red color.
  • Describe how oxygen is bound to hemoglobin and transported to body tissues

• RBC Physiology

  • Most of these functions are attributed to hemoglobin content.
  • RBCs facilitate gas exchange through a protein called hemoglobin.
  • Oxygen bound hemoglobin is called oxyhemoglobin.
  • Hemoglobin bound oxygen causes a gradual increase in oxygen-binding affinity until all binding sites on the hemoglobin molecule are filled.
  • Hemoglobin can also bind to carbon dioxide, which creates carbamino-hemoglobin.

• Transport of Carbon Dioxide in the Blood

  • Binding of carbon dioxide to hemoglobin is reversible.
  • However, hemoglobin binds to the free H+ ions, limiting shifts in pH.
  • The H+ ion dissociates from the hemoglobin and binds to the bicarbonate ion.
  • Carbon monoxide has a greater affinity for hemoglobin than does oxygen.
  • When carbon monoxide (CO) in the body increases, the oxygen saturation of hemoglobin decreases since hemoglobin will bind more readily to CO than to oxygen.

• Red Blood Cells

  • Hemoglobin is packed into red blood cells at a rate of about 250 million molecules of hemoglobin per cell.
  • In mammals, the lack of organelles in erythrocytes leaves more room for the hemoglobin molecules.
  • Not all organisms use hemoglobin as the method of oxygen transport.
  • Studies have found that hemoglobin also binds nitrous oxide (NO).
  • Unlike hemoglobin, hemolymph is not carried in blood cells, but floats free in the hemolymph.

• RBC Anatomy

  • Hemoglobin molecules are the most important component of RBCs.
  • Hemoglobin is a specialized protein that contains a binding site for the transport of oxygen and other molecules.
  • The RBCs' distinctive red color is due to the spectral properties of the binding of hemic iron ions in hemoglobin.
  • Each human red blood cell contains approximately 270 million of these hemoglobin biomolecules, each carrying four heme groups (individual proteins).
  • Hemoglobin comprises about a third of the total RBC volume.

• Carbon Dioxide Transport

  • CO2 is carried in blood in three different ways: dissolved in plasma, bound to hemoglobin, or as a biocarbonate ion.
  • While oxygen binds to the iron content in the heme of hemoglobin, carbon dioxide can bind to the amino acid chains on hemoglobin.
  • When carbon dioxide clings to hemoglobin it forms carbanimohemoglobin.
  • Dissolved carbon dioxide is already able to diffuse into the alveolus, while hemoglobin-bound carbon dioxide is unloaded into the plasma.
  • Hemoglobin is a tetramer of alpha (red) and beta (blue) subunits with iron containing heme groups (green).

• Homologs, Orthologs, and Paralogs

  • For example, the hemoglobin gene of humans and the myoglobin gene of chimpanzees are paralogs.
  • The genes encoding myoglobin and hemoglobin are considered to be ancient paralogs.
  • Similarly, the four known classes of hemoglobins (hemoglobin A, hemoglobin A2, hemoglobin B, and hemoglobin F) are paralogs of each other.
  • While each of these proteins serves the same basic function of oxygen transport, they have already diverged slightly in function: fetal hemoglobin (hemoglobin F) has a higher affinity for oxygen than adult hemoglobin.

• Anemia

  • Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood resulting in tissue hypoxia.
  • Anemia is a decrease in number of red blood cells (RBCs), or less than the normal quantity of hemoglobin in the blood.
  • It can include the decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin deficiencies.
  • Because hemoglobin (found inside RBCs) normally carries oxygen from the lungs to the tissues, anemia leads to hypoxia (lack of oxygen) in organs.
  • Iron is an essential part of hemoglobin, and low iron levels result in decreased incorporation of hemoglobin into red blood cells.

• Sickle-Cell Disease

  • It is caused by a change in hemoglobin's primary structure .
  • Hemolytic crises are acute accelerated drops in hemoglobin level.
  • Abnormal hemoglobin forms can also be detected on hemoglobin electrophoresis, a form of gel electrophoresis on which the various types of hemoglobin move at varying speeds.
  • Sickle cell anemia is caused by a change in hemoglobin's primary structure
  • The inset image shows a cross-section of a normal red blood cell with normal hemoglobin.