• Question: what are genome cells made up of xx ??

    Asked by to Rebecca, Heather on 18 Jun 2014. This question was also asked by .
    • Photo: Rebecca Gladstone

      Rebecca Gladstone answered on 18 Jun 2014:

      Hi there!
      A genome refers to a complete set of DNA of an organism, it is the complete set of instructions for an organism. Every single cell in a large organism like us needs a copy of all the DNA so that it has the instructions to copy itself and make new cells. The genome is in every single cell within us, and different cells will use different parts of the same genome to become specialised at their specific jobs. Your genome and my genome will be different but within all our cells we will have the same copy of our own genome.
      All genomes don’t need to belong to cells though, viruses all have a genome that they contain in a protein shell, viruses cannot copy their genome though to make new viruses so they break into cells and hijack the machinary the cell uses to copy its genome.

      Human genomes are made up of 23 pairs of chromosomes. If a genome taken from any cell in a human for example, contains two X chromosomes then that human would be female, if instead it had one X and one Y then they would be male as it is the combination of the X and Y chromosomes that are part of your genome that decide what gender you will be!

    • Photo: Heather Ritchie

      Heather Ritchie answered on 19 Jun 2014:

      Rebecca has given you a fantastic answer!

      The only thing I could add to this is that cell sizes will be different between species because the total size of the genome is very different! We don’t know why the genome size is so different as it is not always DNA that codes for genes that get larger/smaller but sometimes the “junk” in between gets bigger/smaller too. It’s a great mystery!

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