BIO 352 Chapter Notes - Chapter 8: Polyploid, Chromosome, Haploinsufficiency
Genetics Reading Chapter 8
•Aneuploidy: an organism gains or loses one or more chromosomes (2n +/- x)
•Monosomy: loss of a single chromosome (2n-1)
•Turner Syndrome (45,X)
•Haploinsufficiency: single copy of a recessive gene may not be enough for sustaining the
organism
•Trisomy: Gain of a single chromosome (2n+1)
•Less fatal compared to monosomy
•Trisomy 21; Down Syndrome (47,21+)
•Patau Syndrome (47,13+)
•Edwards Syndrome (47,18+)
•Euploidy: complete haploid sets of chromosomes are present
•Polyploidy: More than two sets of chromosomes are present
•3 sets: Triploids (3n)
•4 sets: Tetraploids (4n)
•Odd # of chromosome sets are not reliably maintained
•Autopolyploidy: addition of 1+ sets of chromosomes identical to the normal haploid complement of
the same species
•Each set of chromosomes identical to parent
•Triploids: AAA Tetraploids: AAAA
•Autotetraploids more likely to be found than autotriploids due to even number of
chromosomes
• Larger cell size than their diploid relatives
•Allopolyploidy : Combination of chromosomes sets from different species occurring via
hybridization
•Hybridizing two closely related species; Horse + Donkey = Mule
•Offsprings are usually sterile b/c of inability to produce viable gametes
•Double the chromosomes of the sterile hybrid to produce a Fertile Amphidiploid
(Allotetraploid)
•Since 2 homologs of each chromosome are present , meiosis occurs normally
•Chromosomal Variation occurs during the production of gametes: nondisjunction
Class Notes Continued:
For a molecule to serve as the genetic material, it must be able t0
Replicate
Store information
Express information
Allow variation by mutation
Chemical structure of genetic material is important for understanding these varied functions
Searching for Genetic Material
Thomas Hunt Morgan
oWorked with fruit flies
Specifically with eye color
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Document Summary
Genetics reading chapter 8: aneuploidy: an organism gains or loses one or more chromosomes (2n +/- x, monosomy: loss of a single chromosome (2n-1) Haploinsufficiency: single copy of a recessive gene may not be enough for sustaining the organism: trisomy: gain of a single chromosome (2n+1) Edwards syndrome (47,18+: euploidy: complete haploid sets of chromosomes are present, polyploidy: more than two sets of chromosomes are present. Odd # of chromosome sets are not reliably maintained. Autopolyploidy: addition of 1+ sets of chromosomes identical to the normal haploid complement of the same species. Autotetraploids more likely to be found than autotriploids due to even number of chromosomes. Allopolyploidy : combination of chromosomes sets from different species occurring via hybridization. Hybridizing two closely related species; horse + donkey = mule. Offsprings are usually sterile b/c of inability to produce viable gametes. Double the chromosomes of the sterile hybrid to produce a fertile amphidiploid (allotetraploid)
