Cytogenetics Flashcards
Refers to the presence of three or more haploid sets of chromosomes
Polyploidy
Usually not viable. Inability to synapse and form tetrads impairs meiosis
Animal Polyploidy
Plant Polyploidy: sometimes these are viable because plants can use ___ chromosomes are copied, but a cytoplasmic division does not occur
Somatic doubling
All chromosome sets from the same species (double fertilization)
Autopolyploidy
Two different species contribute to the extra chromosomes
Allopolyploidy
Failure to separate
Non-disjunction
The process of meiosis in mammalian females is halted until the onset of ___
Puberty
The result of non-disjunction of homologous chromosomes during meiosis
Aneuploidy
Half missing a chromosome
Monosomy
If non-disjunction occurs during ___, all four gametes are defective
Anaphase I
Half have an extra chromosome
Trisomy
If non-disjunction occurs during ____, half of the gametes would be normal
Anaphase II
___ leads to spontaneous abortion
Autosomal Monosomy
Most ___ leads to spontaneous abortion
Autosomal Trisomy
___ causes Patau Syndrome
Trisomy 13
___ causes Edwards Syndrome
Trisomy 18
___ causes Down Syndrome
Trisomy 21
Mental development stalls at 6 month stage; small or fused eyes, cleft palate, kidney and heart abnormalities
Patau Syndrome
Mental development stalls at 6 month stage; heart and liver defects; clenched fists
Edwards Syndrome
Mild to moderate mental retardation; short stature, broad hands, epicanthal eyelids
Down Syndrome
Female: Karyotype is 45, XO
Short, less breast tissue, infertile (amenorrhea)
No Barr bodies
Turner’s Syndrome
Male: Karyotype is 7, XXY
Tall, less body hair, less muscular, infertile
1 Barr Body
Klinefelter’s Syndrome
Errors of crossing over
Structural Aberrations
Chromosome breaks, reattaches in the wrong place. Results include chromosomes with 2 copies of the same allele or missing an allele
Deletions and Duplications
A segment of a chromosome reattaches in a “flipped” orientation
Inversions
Recombination (crossing over) between non-homologous chromosomes
Translocations
The centromere is not included in inverted segment
Paracentric Inversions
The centromere is included within the inverted segment
Pericentric Inversions
___ and ___ contain gene deletions and duplications
Acentric and Dicectric
__ cannot attach to the spindle during cell division, so it eventually gets lost, leading to aneuploidy
Acentric
___ requires formation of a translocation heterozygote
Synapsis
