Chromosomal Mutations

Karyotype• arrangement of chromosomes from one body

cell

Sex Chromosomes

• Determine the sex of the individual• In humans: X and Y chromosomes

• X chromosome larger than Y chromosome

• All female gametes (egg cells) contain an X chromosome

• Male gametes (sperm) can contain either an X or Y chromosome

• Gender of child determined by father–50% chance child will be male and 50%

female

Atypical Meiosis• Chromosomes do not separate properly

during meiosis• Results in gametes with too little or too

much genetic information

Down Syndrome• Zygote contained 47 chromosomes• 3 copies of chromosome 21

Sex Chromosome Disorders• Klinefelter syndrome:

males born with 2 X chromosomes

• Turner Syndrome: female born with only 1 X chromosome