Human Growth and Development / Unit 2 HGD 0152 short lesson, about 20 seconds
Mitosis and Meiosis
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The idea
Mitosis is ordinary cell division, giving each new cell all forty-six chromosomes; meiosis makes gametes, egg and sperm, with twenty-three each.
In practice
An egg and a sperm, twenty-three chromosomes each, joining at fertilisation to restore forty-six.
Where people slip
Which chromosome from each pair enters a gamete is largely random, giving about eight million possible combinations.
Your place on the trail
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