• Question: how is it that when you are being conceived you get 23 chromosomes of each parent then why do you only have 23

    Asked by 363urak39 to anuantony, Duncan, Jayne, Katherine, Sajid on 8 Nov 2017.
    • Photo: Duncan McNicholl

      Duncan McNicholl answered on 8 Nov 2017:

      You have 23 pairs of chromosomes. You’re quite right that you get 23 from each parent, but each of the 23 is one of a pair, which all have the same kind of genes on them, so one chromosome might have the hair colour genes on it and another might have the genes that make your liver on it. Because you get two of each, you have two copies of almost all the genes in your body, except that you might have one X chromosome from your mum and one Y chromosome from your dad, which would normally make you a boy. If that’s the case, then you only have one copy of some of the genes, because the X and Y chromosomes are different to each other.

    • Photo: Sajid Javed

      Sajid Javed answered on 15 Nov 2017:

      Chromosomes are made up of two copies of each gene. Sex cells from parents contain one copy of each gene. During fertilization the two cells combine and make the 23 chromosomes with two copies of each gene. From these genes the dominate one is usually expressed. for example, if parent 1 has brown eyes and parent 2 has green eyes you have a 50% chance of having brown eyes, 37.5% of green and 12.5% chance of blue eyes.

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