Somatic cells
• Most of the body's cells
• Diploid (2n) : 46 chromosomes
Reproductive cells: gametes
• Sperm and egg cells
• Haploid (1n): 23 chromosomes
Interphase
• Cell doubles in size and DNA during interphase
• 90-95% of cell cycle
• G1: cell grows without replicating DNA
• S: synthesis phase, DNA replicates
• G2: cell synthesizes proteins in preparation for mitosis
• Chromosomes condensed during mitosis: uncondensed (chromatin form) for rest of cell cycle
- Somatic cell division
Prophase
• Centrosomes migrate to opposite sides of cell
• Mitotic spindles form from centrosomes
Prometaphase
• Nuclear envelope fragments
• Nucleolus disappears
• Sister chromatids attached to each other at their centromeres until anaphase
Metaphase
• Chromosomes line up at metaphase plate
Anaphase
• Sister chromatids move to opposite sides of cell
Telophase
• Nuclear envelope reforms
Cytokinesis
• Cytoplasm divides cell into two
• Produces 2 diploid daughter cells with identical genomes
Mitosis
• Division of nucleus into 2 daughter nuclei
Cytokinesis
• Division of cytoplasm
CLINICAL CORRELATION
Aneuploidy
• Sister chromatids do not separate properly during cell division (mostly meiosis but also occurs during mitosis)
• Daughter cells with extra or missing chromosome
• Common in cancer cells