Q24.2-4CC - Campbell Biology

Question

Review the process of meiosis in Figure 13.8. Describe how an error during meiosis could lead to polyploidy.

Step-by-Step Solution

Answer

An error such as improper separation of homologous chromosomes or sister chromatids in the anaphase I of the meiosis causes polyploidy. 

Step 1: Meiosis

A type of cell division that exhibits in germ cells of the organisms is called meiosis. It takes place in two stages; meiosis I and meiosis II. At the end of meiotic division, four daughter cells are formed. The daughter cell comprises a haploid number of chromosomes; therefore, it is called reductional division.

Step 2: Polyploidy

The genetic condition is when an individual possesses more sets of chromosomes than the normal numbers. For example, most multicellular organisms are diploid organisms. The presence of three sets of chromosomes is called triploid. 

 

The condition is further classified as tetraploid, pentaploid, and hexaploid based on the number of chromosomes. 

Step 3: Causes of polyploidy

The recombination events in the meiotic division fail to occur properly and lead to the nondisjunction of sister chromatids. Therefore, daughter cells end up having extra sets of chromosomes. It can also arise due to the failure of cytokinesis. 

 

In humans, polyploidy always leads to miscarriage during pregnancy. It is common in plants.