Chapter 13 Flashcards
(20 cards)
number of x chromosomes in male
1
number of x chromosome in female
2
males have a … chromosome
y
In female cells, 1 X chromosome is inactivated and condensed into a
Barr body
Females heterozygous for X-linked genes are thus
genetic mosaics (express the dominant allele in some cells, the recessive allele in other cells)
sex-linked traits
controlled by genes on the X or Y chromosome; show inheritance patterns different than those of genes on autosomal chromosomes
nondisjunction
during meiosis, 1 pair of chromosomes don’t split apart causing 2 haploids to have 3 chromosomes and the other 2 haploids to have 1 chromosome
trisomy
1 extra chromosome
monosomy
1 less chromosome
Nondisjunction of sex chromosomes can result in:
- XXX triple-X syndrome daughters
- XXY sons
- XO daughters
- XYY sons
- OY nonviable zygotes
XO daughters
Turner syndrome
XXY sons
Klinefelter syndrome
XYY sons
Jacob syndrome
Cri-du-chat syndrome occurs when
a section of chromosome 5 is missing, this deletion occurs during gamete development
Genomic imprinting
phenotype produced by a particular allele depends on which parent contributed the allele
A mutated chromosome 15 causes:
Prader-Willi syndrome or Angelman syndrome
when a mutated chromosome 15 is from the father
Prader-Willi syndrome
when a mutated chromosome 15 is from the mother
Angelman syndrome
gene-linked
occurs when genes are close together on the chromosome so crossing over doesn’t occur
gene-not linked
occurs when genes are on opposite sides of the chromosome so crossing over can occur
