Question

Which tetrad analysis uses first and second division segregation pattern types​

Answer 1

Answer:

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Explanation:

Tetrads and centromere mapping

There has been no crossing over between the gene and the centromere when two alleles segregate in to separate nuclei at the first division.

This is called first-division segregation and produces the 2:2 (or 4:4 in an octad) first-division segregation pattern (MI pattern).

There has been crossing over between the gene and the centromere when two alleles segregate in to separate nuclei at the second division.

This is called second-division segregation and produces the 2:2:2:2 or 2:4:2 (in an octad) second-division segregation patterns (MII pattern).

To calculate the distance of a locus from its centromere in map units, simply measure the percentage of tetrads showing second-division segregation patterns for that locus and divide by two.

When considering two genes, the following possibilities arise.

The loci are on separate chromosomes.

The loci are on the same chromosome but on opposite sides of the centromere.

The loci are on the same chromosome and on the same side of the centromere.