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How many chromosomes do humans have ?

  1. Oct 5, 2009 #1
    I have always known that humans have 46 chromosomes, but recently someone told me that we have actually 47 chromosomes. He said we have 46 nuclear chromosomes and one mitochondrial chromosome. Is this true?! Is this mitochondrial genetic information a real chromosome or does it differ in structure/function from the other nuclear chromosomes?! What does scientists say about it?! Is it counted as a chromosome ?!
  2. jcsd
  3. Oct 5, 2009 #2

    jim mcnamara

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    Staff: Mentor

    The DNA in a mitochondrion is circular like the DNA in bacteria.
    Humans have 46 chromosomes in pairs, so we really have 23 chromosomes. 22 are somatic chromosomes and one is a sex chromosome - either X chromosome or Y chromosome.

    IMO circular does not count as a chomosome, aside from the fact that a single cell can have many mitochondria, each with its own copy of DNA.
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