Question

1. A flower is heterozygous for the following inversion of chromosome 1 (dot=centromere)

A    B     C    ●   D    E    F    G

a     b      e     d     ●    c     f     g

a. Is this a paracentric or pericentric inversion?

I am thinking Pericentric?

b. Draw the pairing configuration at prophase I including all 4 chromatids.

I wasnt too sure how to map the loop out for this one

c. Give the genotypes of the gametes from this meiosis if there is a single cross-over between genes D and E, and tell whether the gametes will be viable or nonviable.

Answer 1

Answer-

1) a) The inversion is pericentric because the inverted segment contains the centromere, i.e., it involves one break on either side of the centromere.

Crossing over in pericentric inversion results in the formation of the chromosome which have duplications for some genes anf deletions of others. The gametes receiving chromosomes with these deficiencies are inviable.

Picture is given below:

A B C D E F G Percentric Inversion a be d af g. Prophase I stage of meiosis after DNA replication (Each homologous chromosome carries 2 sister cromatids) B C D E F G sister cloromatids B C D E F G b ed c f g sister cloromatids. b e a C f g A A a a pairing (b) 0 crossing over (single) between gene D and E flotto Sametes A B C D E F a. 2 Normal product viable B C D e b a peletion & Duplication - Inviable a be det Normal product viable are acta@ Iniciable)