BIO 351 Lecture Notes - Lecture 10: Monosomy, Synteny, Polyploid
Polyploidy and Synteny Objectives
1. Distinguish between aneuploidy and polyploidy (monosomy, trisomy, triploidy)
− Aneuploidy = extra/fewer copies of some chromosomes
o Monosomy = 2n – 1 (in diploids)
o Trisomy = 2n + 1 (in diploids)
− Polyploidy = heritable condition of possessing more than two complete sets of chromosomes
o Being more than haploid or diploid
o Triploid = containing three homologous chromosomes for each chromosome
− If you want to make viable gametes, you need two of each chromosome
2. Triploid plants tend to have low fertility… why? meiosis, trivalent What is the advantage of triploid plants in
agriculture?
− Triploid plants tend to be seedless due to trouble with trivalent formation and correct segregation during
meiosis
− Polyploidy also allows for breeding flexibility
3. Distinguish between autopolyploids and allopolyploids.
− Allopolyploids = duplication of genome due to hybridization of two distinct species
o Varying degrees of heterozygosity depending on the divergence of the parental genomes
o Heterozygosity is most apparent in the gametes that they produce
o Final ploidy acts like diploid however we know that it arose from polyploidy
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Document Summary
Distinguish between aneuploidy and polyploidy (monosomy, trisomy, triploidy) Aneuploidy = extra/fewer copies of some chromosomes: monosomy = 2n 1 (in diploids, trisomy = 2n + 1 (in diploids) Polyploidy = heritable condition of possessing more than two complete sets of chromosomes: being more than haploid or diploid, triploid = containing three homologous chromosomes for each chromosome. Triploid plants tend to be seedless due to trouble with trivalent formation and correct segregation during meiosis. Polyploidy also allows for breeding flexibility: distinguish between autopolyploids and allopolyploids. Autopolyploids = duplication of genome within a species: essentially homozygous at every locus in the genome. Autopolyploid vigor decreases with increased chromosome number. What is the role of polyploidy in stabilizing hybrid vigor? (allopolyploid, infertile hybrid) Hybrid vigor = heterosis = where the polyploid offspring is more vigorous and healthy than either of the two diploid parents: when the hybrid intermediate is favored over either parent/donor, this is exclusive to allopolyploids.
