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I know that a normal human cell has 23 pairs of chromosomes (total: 46). On the other hand, a gamete has only 23 chromosomes. Which chromosome does the gamete choose out of each pair?

And if "One of each pair of chromosomes comes from the mother, the other from the father.", then the chromosomes of a gamete could be an exact copy of the chromosomes in a grandfather's gamete?

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    $\begingroup$ Have you read the basic Mendelian genetics; check the law of independent assortment. $\endgroup$
    – WYSIWYG
    Commented Sep 7, 2015 at 4:40
  • $\begingroup$ Therefore, there are many levels of variation. $\endgroup$
    – Turbo
    Commented Sep 9, 2015 at 7:12

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The gamete doesn't "choose" one or the other. Both are made and you get two gametes, one for each.

Also it's unlikely to be an "exact copy" due to recombination and random or independent assortment. There are also smaller influences on genetic variation, and epigenetics, but at this level of question I think you should focus on those two.

Was this homework? If so it should be tagged.

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    $\begingroup$ Also there is random assortment, so even without taking recombination into account there are 2^23 possible combinations for assortment, or about 8.5 million combinations. Throw recombination into the mix and you start to see why there is so much variety, even among siblings. $\endgroup$
    – AMR
    Commented Sep 7, 2015 at 4:13
  • $\begingroup$ No this is not homework, just personal study, but thanks for your answer, it was well worth a read. $\endgroup$
    – Turbo
    Commented Sep 7, 2015 at 16:39
  • $\begingroup$ Great links as well! $\endgroup$
    – Turbo
    Commented Sep 7, 2015 at 17:56

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