Chapter 7.4: Errors during Cell Division Can Result in Changes in Chromosome Number

Flashcards from Chapter 7.4 of Principles of Life, 3rd Edition.

Nondisjunction

A cell division error where a chromosome fails to separate, resulting in an unequal number of that specific chromosome in the daughter cells (aneuploidy)

Aneuploidy

The condition of a cell, or organism, having an unequal number of copies of each chromosome; this is often harmful for cells

• Numbered according to the number of chromosomes present:

  • 0: nullisomic

  • 1: monosomic

  • 3: trisomic

  • 4: tetrasomic

Polyploidy

The possession of more than two entire sets of chromosomes, often caused by errors during the M phase of mitosis or meiosis:

• Spindle formation failure and thus no cytokinesis resulting in tetraploidy (4n)

• Failure of cytokinesis to occur, also resulting in tetraploidy

Many plants and fungi exhibit this with growth and consumption benefits; however, it is rarely beneficial in animals due to large reductions in fertility

Polyspermy

A common mechanism that causes polyploidy by way of more than one male gamete fertilizing a single female gamete