Solutions For An Introduction to Genetic Analysis Chapter 4 Problem 39P

All asci are classified as parental ditype (PD), non-parental ditype (NPD), or tetrad (T) and analyzed as to whether segregation has occurred in the first or second meiotic division. This can be done using the following table:

For cross 1: PD = NPD

The frequency of recombinants (RF) can be calculated as follows:

Hence, the genes are not linked.

For a centromere, the distance between the gene and centromere:

Hence, gene a is close to the centromere.

For b centromere:

For cross 2: PD >> NPD

The RF can be calculated as follows:

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

Hence, gene a is close to the centromere.

For b centromere:

For cross 3: PD >> NPD

The RF can be calculated as

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

Hence, gene a is close to the centromere.

For b centromere:

For cross 4: PD >> NPD

The RF can be calculated as

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

For b centromere:

For cross 5: PD = NPD

The RF can be calculated as

Hence, the genes are not linked.

For a centromere, the distance between the gene and centromere:

For b centromere:

For cross 6: PD >> NPD

The RF can be calculated as

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

For b centromere:

For cross 7: PD >> NPD

The RF can be calculated as

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

For b centromere:

For cross 8: PD = NPD

The RF can be calculated as

Hence, the genes are not linked.

For a centromere, the distance between the gene and centromere:

For b centromere:

For cross 9: PD >> NPD

The RF can be calculated as

Hence, the genes are linked.

For distance between a and b –

For a centromere, the distance between the gene and centromere:

For b centromere:

Cross 10: PD = NPD

The RF can be calculated as

Hence, the genes are not linked.

For a centromere, the distance between the gene and centromere:

For b centromere:

Cross 11: PD = NPD

The RF can be calculated as

Hence, the genes are not linked.

For a centromere, the distance between the gene and centromere:

For b centromere:

The map distances can be shown in the following ways: