12.4: Alternations of chromosome number or structure cause some genetic disorders Flashcards
nondisjunction
the members of a pair of homologous chromosomes do not move apart properly during meiosis 1 or sister chromatids fail to separate during meiosis 2.
aneuploidy
an abnormal number of particular chromosomes
monosomic
a condition where a gamete has no copy of a particular chromosome, leads to a missing chromosome in the zygote
trisomic
where a chromosome is present in triplicate in the zygote, extra chromosome, Down syndrome
polyploidy
where an organism has more than 2 complete chromosomes set in all somatic cell, Plants can get these abnormal numbers, yet they can still function
down syndrome
where there the cell is trisomic for chromosome 21, trisomy 21, 47 chromosomes in each cell
Klinefelter syndrome, men
XXY genotype, does not affect males that much, testes small though,
Turner syndrome, women
monosomy X, immatured sexual organs for females
cri du chat
where there is deletion at chromosome 5, leads to death at early infancy
genomic imprinting
a phenomenon where the phenotypic effect of a gene may depend on which allele is inherited from each parent
reciprocal translocation
fragments switch places
genomic imprinting
involves the silencing of certain genes that are “stamped” with an imprint during gamete production
deletion
when a chromosomal fragment is lost
duplication
produced when a broken fragment may become reattached as an extra segment to a sister or nonsister chromatid
inversion
a chromosomal fragment can reattach to the original chromosome but in the wrong way
