BIO 352 Lecture Notes - Lecture 7: Chromosome Abnormality, Klinefelter Syndrome, Meiosis
Variation in chromosome number and arrangement
ď‚·Chromosome does not segregate all the way to the pole of the spindle,it was left out in
the cytoplasm and lost, you’ll lose a chromosome
ď‚·Reciprocal crosses, offspring identical to mother
ď‚·Maternal Effect
oA maternal effect is a situation where the phenotype of an organism is
determined not only by the environment it experiences and its genotype, but also
by the environment and genotype of its mother.
oEx. Coiling direction of snail shells
The coiling phenotype that is seen in the offspring is controlled by the
genotype of the mother.
ď‚·Chromosome Variation
oAlthough most diploid species normally contain precisely two haploid
chromosome sets, there are many known variations
A change in the totaly # of chromosomes
The deletion or duplication of genes or segments of chromosome
Rearrangements of the genetic material either within or among
chromosomes (inversions and translocations)
ď‚·Many types of chromosome abnormalities
oVariation in #
Aneuploids: total # of chromosomes is not an exact multiple of haploid
set( ex. 23 → 46 )
Trisomic (2N +1)
Down syndrome
Monosomic (2N -1 )
Turner Syndrome
Tetrasomic (2N +2 )
Klinefelter Syndrome
Nullisomic (2N -2 )
Humans will not survive in this condition
Polyploids (3N, 4N, etc) (Euploids; exact multiple of haploid number)
Autopolyploids
2 complete copies of the genome of same species
Diploid → Triploid + Tetraploid
Ex. Potatoes
Chrysanthemum: 1N (haploid set) = 9
Many closely related species:
2N = 18 (diploid)
4N = 36 (tetraploid)
6N =54 (Hexaploid)
8N=72 (octoploid)
All are fertile because of an even number of
chromosome sets
Odd # of chromosomal sets in autopolyploids
causes sterility because meiosis proceeds
abnormally and produces unbalanced gametes
Cells of an individual get bigger, phenotypic
consequence
Exhibit non-mendelian segregation patterns

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Document Summary
Chromosome does not segregate all the way to the pole of the spindle,it was left out in the cytoplasm and lost, you"ll lose a chromosome. Maternal effect: a maternal effect is a situation where the phenotype of an organism is determined not only by the environment it experiences and its genotype, but also by the environment and genotype of its mother, ex. The coiling phenotype that is seen in the offspring is controlled by the. Chromosome variation genotype of the mother: although most diploid species normally contain precisely two haploid chromosome sets, there are many known variations. A change in the totaly # of chromosomes. The deletion or duplication of genes or segments of chromosome. Rearrangements of the genetic material either within or among chromosomes (inversions and translocations) Many types of chromosome abnormalities: variation in # Aneuploids: total # of chromosomes is not an exact multiple of haploid set( ex. Humans will not survive in this condition.
