BIO 353 Chapter Notes - Chapter 8: Thomas Hunt Morgan, Patau Syndrome, Turner Syndrome
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
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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. Edwards syndrome (47,18+: trisomy: gain of a single chromosome (2n+1, 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)