Question

Give the structural defects of chromosomes.

Answer 1

1) Deletion- loss of a segment of a chromosome. it is of two types
a) terminal - lost segment includes telomere.
b) interstitial - a segment between telomere and centromere is lost

2) Duplication - a chromosome segment present in more than two copies in the sme nucleus. it is of four types-
a) tandem - additional chomosome is just after the normal.
a-b-c-d-e-f-g-h-@-i-j-k-l
it is normal


a-b-c-d-e-c-d-e-f-g-h-@-i-j-k-l it is tandem duplication.

b) reverse - same but the segment is inverted
a-b-c-d-e-e-d-c-f-g-h-@-i-j-k-l

c) displaced - additional sgment located away the normal segment in same chromosome.
a-b-c-d-e-f-g-c-d-e-h-@-i-j-k-l

d) translocation - segment on another chomosome..
m-n-o-p-c-d-e-q-@-r-s-t-u-v

3) Inversion - a chromosome segment contains genes in a sequence which is reversed. it is of 2 types
a) paracentric - inverted segment does not contain centromere.
b) pericentric - inverted segment contain centromere.....

4) Translocation- chromosome segment integrated into nonhomologous chromosome matlab doosare chromosome par.. means on another chromosome......
it is also of 2 types-----
a) simple - integration is simple without any speciallity.
b) reciprocal - integrated inversially...