Meiosis Mistakes and Nondisjunction

Flashcards covering gamete formation, errors in meiosis (aneuploidy, nondisjunction), types of chromosomal abnormalities (monosomy, trisomy, polyploidy), common nondisjunction disorders, and diagnostic methods like karyotyping.

Gametogenesis

The process of gamete formation at the end of meiosis, where gametes differentiate into specialized cells.

Spermatogenesis

The process of sperm formation: Diploid spermatogonia develop into primary spermatocytes, which then form 4 spermatids.

Oogenesis

The process of egg formation: Diploid Oogonia develop into primary oocytes, which then form 1 egg and 3 polar bodies.

Aneuploidy

An error in meiosis where chromosomes do not separate properly, leading to cells having too many or too few chromosomes.

Nondisjunction

The failure of homologous chromosomes to separate in meiosis I, or the failure of sister chromatids to separate in meiosis II, causing aneuploidy.

Monosomy

A condition where a fertilized cell is missing a chromosome.

Trisomy

A condition where a fertilized cell has an extra copy of a chromosome.

Polyploidy

A condition where every chromosome is duplicated, resulting in genetic states like 3n or 4n.

Down Syndrome (Trisomy 21)

A genetic disorder resulting from nondisjunction of chromosome 21, where the offspring receives 3 copies instead of 2, causing mental and physical differences.

Turner Syndrome

A nondisjunction disorder where females are born with only one X chromosome, typically resulting in sterility.

Klinefelter Syndrome

A nondisjunction disorder where males have 2 X and 1 Y chromosomes, usually resulting in sterility and display of feminine traits.

Patau Syndrome (Trisomy 13)

A nondisjunction disorder causing severe developmental problems affecting the brain, kidney, and heart.

Karyotyping

A diagnostic method used to identify chromosomal abnormalities prenatally by counting, comparing, and arranging chromosomes.

Amniocentesis

A prenatal diagnostic procedure where cells for testing are collected from the amniotic fluid.

Chorionic Villus Sampling

A prenatal diagnostic procedure where cells for testing are collected from villi along the lining of the uterus.

Maternal Age Effect on Nondisjunction

The increased likelihood of nondisjunction in meiosis I in older oocytes (over age 35) due to these cells stopping at prophase I until ovulation and aging with the individual.