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Unformatted text preview: ntrast to animals, plants commonly
exhibit In many instances, polyploid strains of
plants display outstanding agricultural
characteristics Polyploids having an odd number of chromosome sets
are usually sterile
are These plants produce highly aneuploid gametes NATURAL AND EXPERIMENTAL WAYS
TO PRODUCE VARIATIONS IN
CHROMOSOME There are three natural mechanisms by
which the chromosome number of a species
1. 2. 3.
3. Meiotic Nondisjunction
Meiotic Nondisjunction refers to the failure of chromosomes
to segregate properly during anaphase
to Meiotic nondisjunction - haploid cells that have too
many or too few chromosomes
many If such a gamete participates in fertilization The resulting individual will have an abnormal
chromosomal composition in all of its cells
chromosomal Meiotic Nondisjunction
Meiotic In rare cases, all the chromosomes can undergo
nondisjunction and migrate to one daughter cell
nondisjunction This is termed ______________________
______________________ It results in a diploid cell and one without chromosomes
The chromosome-less cell is nonviable
The diploid cell can participate in fertilization with a
normal Mitotic Abnormalities
Abnormalities Abnormalities in chromosome number often occur
after In this case, the abnormality occurs in mitosis not meiosis 1. Mitotic disjunction
1. 2. Chromosome loss
2. Mitotic Abnormalities
Mitotic Genetic abnormalities that occur after fertilization
lead to _____________.
_____________. The size and location of the mosaic region depends
on the timing and loca...
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This document was uploaded on 03/05/2014 for the course CELL 2050 at Tulane.
- Spring '12