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Chromosomal Disorders. What happens when meiosis goes wrong?. Karyotype. Human Chromosomes. Humans have 46 chromosomes Two sex chromosomes - determine an individual’s sex Females have two copies of the large X chromosome Males have one X and a smaller Y chromosome. Human Chromosomes.
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Chromosomal Disorders What happens when meiosis goes wrong?
Human Chromosomes • Humans have 46 chromosomes • Two sex chromosomes- determine an individual’s sex • Females have two copies of the large X chromosome • Males have one X and a smaller Y chromosome
Human Chromosomes • The remaining 44 chromosomes are known as autosomal chromosomes or autosomes • Males and females are born in a roughly 50:50 ratio • All human egg cells carry a single X • Half of all sperm carry and X and the other half carry a Y
Chromosomal Mutations • Chromosomal mutations involve changes in the number or structure of chromosomes • Lead to diseases or disorders
Changes in chromosome structure • Deletion • Part of a chromosome is lost during cell division • Chromosome is missing genes • Duplication • Region of chromosome is repeated • Translocation • Piece of a chromosome moves to another chromosome
Nondisjunction • Homologous chromosomes fail to separate during meiosis I • Sister chromatidsfail to separate during meiosis II OR Creates gametes with the wrong number of chromosomes!