Changes in Chromosome Number
Next Generation: HS.LS3.2 HS.LS3.2

Changes in Chromosome Number

Author: Nathan Lampson

This lesson will explore what types of events can change the number of chromosomes an individual has and the physical outcomes of having an abnormal number of chromosomes.

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  • Nondisjuction

    When chromosomes don’t separate during meiosis causing gametes to have abnormal numbers, Down syndrome is an example of this.

  • Down Syndrome

    A genetic disorder in which the 21st pair of chromosomes have three chromosomes vs. the normal pair, this is called a trisomy.

  • Turner Syndrome

    A genetic condition in which an X chromosome is missing, if the child is not miscarried, the effects can range from non-life threatening to life threatening. People with Turner syndrome are female due to the presence of only an X chromosome, are almost universally infertile and typically have cardiovascular issues along with other organ system problems.

  • Klinefelter Syndrome

    A condition in which a person has an XXY chromosomal pattern; males that inherit this are often infertile, may develop breasts and other female secondary characteristics and possible mental retardation.

  • XYY Syndrome

    A condition in which a male inherits an extra Y chromosome; XYY syndrome doesn’t express any cognitive or life threatening abnormalities, it just tends to make males taller than average.