Topics: Chromosome, Gamete, Aneuploidy Pages: 4 (1569 words) Published: March 10, 2006
Non-Disjunction Causes and Effects
This paper shows the basis of non-disjunction of chromosome, a failure of chromosomes to separate properly during cell division. It emphasizes particularly on how the reproductive cells or gametes is created during reproduction. The gametes of women are eggs and of men are sperms. When the egg and the sperm combine during fertilization at conception, they create a normal offspring with the proper number of chromosomes of 46. Nondisjunction occurs when these chromosome fail to segregate and can cause common abnormality of having an extra chromosome or missing a chromosome in its cells thus creating an offspring with chromosome abnormalities of 45 or 47. Chromosome is a structure located inside the nucleus (center) of a cell that has long DNA molecule and proteins that present in every cell of the body. It also carries portions of the hereditary information needed for that cell to develop. Homologous chromosomes are chromosomes that occur in pairs. Normal humans have twenty-three homologous pairs. A female's egg contains only one representative from each of the 23 chromosome pairs and the male's sperm contains the other half of the 23 chromosome pairs. Eggs and sperm are formed following meiosis to create the total count of 46 chromosomes in a cell of a normal offspring. A normal human normally has a situation of genetic balance. Each gene is working properly and contributing ideally towards that person's development. However, if a chromosome is either removed from or added, it creates a genetic imbalance (nondisjunction) and compromises that individual's development. This means that nondisjunction occurs when it produces the wrong number of chromosomes in a cell, results in severe genetic defects. Nondisjunction is one of the most common genetic disorders in humans, occurring in human pregnancies. It affects hundreds thousands of people in the world. Specifically, nondisjunction is the failure of two members of a...
Continue Reading

Please join StudyMode to read the full document

Become a StudyMode Member

Sign Up - It's Free