Examples of Aneuploidy in Humans: Down Syndrome and More

📚 Quick Study Guide

• 🧬 Aneuploidy Definition: A condition where there's an abnormal number of chromosomes in a cell, differing from the usual diploid number (2n).
• 🔢 Monosomy: The loss of a single chromosome ($2n - 1$).
• ➕ Trisomy: The gain of an extra copy of one chromosome ($2n + 1$).
• 👶 Down Syndrome (Trisomy 21): Caused by an extra copy of chromosome 21.
• 💔 Turner Syndrome (Monosomy X): Females have only one X chromosome (XO).
• 👨 Klinefelter Syndrome (XXY): Males have an extra X chromosome (XXY).
• 🔬 Nondisjunction: The failure of chromosomes to separate properly during cell division (meiosis), leading to aneuploidy.
• 🧮 Incidence: Aneuploidy is more common in older mothers due to increased risk of nondisjunction.

Practice Quiz

1. What is aneuploidy?
   1. A condition with the normal number of chromosomes.
   2. A condition with an abnormal number of chromosomes.
   3. A condition where chromosomes are perfectly paired.
   4. A type of gene mutation.
2. Down syndrome is an example of which type of aneuploidy?
   1. Monosomy
   2. Trisomy
   3. Tetrasomy
   4. Nullisomy
3. Which chromosome is affected in Down syndrome?
   1. Chromosome 13
   2. Chromosome 18
   3. Chromosome 21
   4. Chromosome X
4. Turner syndrome is an example of which type of aneuploidy?
   1. Trisomy
   2. Monosomy
   3. Tetrasomy
   4. Nullisomy
5. What is the chromosomal makeup of individuals with Turner syndrome?
   1. XXY
   2. XO
   3. XXX
   4. XYY
6. Klinefelter syndrome affects individuals of which sex?
   1. Female
   2. Male
   3. Both
   4. Neither
7. What is the chromosomal makeup of individuals with Klinefelter syndrome?
   1. XO
   2. XXY
   3. XXX
   4. XYY