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| [[Image:Hemoglobin ribbon 4subunits.jpg|left|250x240px|Hemoglobin ribbon 4subunits.jpg]] | | See [[Haemoglobin]] |
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| '''Haemoglobin''' (also spelled Hemoglobin and abbreviated Hb or Hgb) is a respiratory pigment, which transports oxygen essential for cellular metabolism.<br>
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| In its quarternary structure is a [[Globular_protein|globular protein]], its chains are closely coiled together to form a compact, almost spherical molecule. A single molecule consists of 4 subunits: two α-polypeptide chains (each identical and containing 141 amino acids) and two β-polypeptide chains (each identical and containing 146 amino acids). The location of the genes for both types of polypeptide chains differs: α-chain gene is located on chromosome 16, the β-chain gene is located on chromosome 11. <ref>Klug William S., Essentials of genetics, 8th edition, 2013, Boston: Pearson, p.376-377</ref><br><br>Each polypeptide is associated with [[Haem_group|haem]], which is the prostatic group that mediates reversible binding of oxygen by haemoglobin. It contains a ferrous (Fe<sup>2+</sup>) ion. Each Fe<sup>2+</sup> ion can combine with a single oxygen molecule (O<sub>2</sub>), making a total of four oxygen molecules that can be carried to the tissues and return carbon dioxide (CO<sub>2</sub>) from the tissue to the lungs.<ref>[Anon]. 2002. Hemoglobin synthesis [Online]. [Accessed 21.11.2014] Available from: http://sickle.bwh.harvard.edu/hbsynthesis.html</ref><br>
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| The cell that produces haemoglobin is called an [[Erythrocyte|erythrocte]] (also known as RBC, red blood cell). Each red cell contains about 280 million molecules of haemoglobin.<ref>Sears, Duane W. 1999. Overview of Hemoglobin's Structure/Function Relationships. [Online]. [Accessed 20.11.2014]fckLRAvailable from: http://mcdb-webarchive.mcdb.ucsb.edu/sears/biochemistry/tw-hbn/hba-overview.htm#Top</ref><br>
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| == References: ==
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| <references />
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Latest revision as of 06:09, 22 October 2015