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

MITOSIS

• 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