One DNA molecule per cell

Replicate to two DNAs.

Now segregate to two daughter cells

If totally random, half of the cells will have too many or too few.

What about human cells with 46 chromosomes (DNA molecules)?

Dosage & loss of heterozygosity & major sources of mutation

in human populations and cancer.

For example, trisomy 21, a 1.5-fold dosage with enormous impact.

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