Chromosomes during Cell Division

Abstract In mitosis, duplicated deoxyribonucleic acid (DNA) goes through a condensation/decondensation cycle. This is followed by nuclear envelope dissolution, mitotic spindle assembly, migration of the sister chromatid pairs to the metaphase plate, division and segregation of identical sets of chromosomes into daughter nuclei and nuclear envelope reformation. This process results in the formation of two genetically identical daughter cells. Dynamic structural changes and the mitotic spindle‐mediated movement are two major features that occur to chromosomes during cell division. Both features are well coordinated with temporal progression of mitosis consisting of five distinct stages (prophase, prometaphase, metaphase, anaphase and telophase), which are regulated by checkpoint mechanisms to maintain genomic integrity. Defects in chromosome segregation are linked to cancer and several genetic diseases. Some enzymes involved in chromosome regulation during cell division have become attractive drug targets. Key Concepts: Mitosis is the process of cell division that results in two genetically identical daughter cells. Mitosis consists of five stages: prophase, prometaphase, metaphase, anaphase and telophase. Chromosomes are classified according to centromere location as metacentric, submetacentric or acrocentric. Chromosome movement in mitosis is a dynamic process controlled by microtubule dynamics and microtubule‐associated motor or nonmotor proteins. Sister chromatid cohesion is established in S phase and is dissolved in two steps in vertebrate mitoses. A kinetochore complex forms at the centromere in mitosis to allow microtubule capture. Mitosis is a coordinated process regulated by checkpoint mechanisms to maintain genomic integrity. Chromosomal missegregation results in cell death or aneuploidy.