Explain how you could determine which individuals were heterozygous by looking at the gel

You can determine it by moving the blue dye on the DNA

If it matched up to the correct lanes with different Alleles, than that individual is a heterozygous , 

If not, than that person is a monozygous

Explanation:

They show marks to work out the mutated alleles by swing them by traditional ones. Compare to normal traditional to affected marks.

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