cell division

• cell division is divided into interphase (functioning and preparing to divide) and M phase (mitosis and cytokinesis)
• g1

  Gap 1 - normal cell growth and functions
• S phase

  Synthesis of DNA
• G2 phase

  Gap 2 - rapid cell growth, and preparation for mitosis
• M phase

  mitosis and cytokinesis
• DNA is less tightly packed during interphase to allow RNA transcription and DNA replication
• Prophase: chromosomes condense, spindle appears outside nucleus, nuclear envelope begins to fragment. Chromosomes attach to spindle microtubules via their kinetochores
• Metaphase: chromosomes line up at the equator, attached to opposite poles
• Anaphase: chromatids separate to form 2 daughter chromosomes, each is pulled towards pole
• Telophase: daughter chromosomes arrive at poles and decondense, new nuclear envelope assembles
• Cytokinesis: cytoplasm is divided into 2 by a contractile ring, pinching the cell in 2
• Egg and sperm are haploid
• Fertilisation generates diploid zygote
• Prophase 1: chromosomes condense, nuclear envelope breaks down, crossing over (for genetic variation)
• Metaphase 1: pairs of homologs move to the equator and attach to spindle
• Anaphase 1: homologs move to opposite poles
• Telophase 1 and cytokinesis: cytoplasm divides, 2 haploid cells
• Prophase 2: new spindle forms around chromosomes
• Metaphase 2: chromosomes line up at equator
• Anaphase 1: centromeres divide, chromatids move to opposite sides
• Telophase 2 and cytokinesis (meiosis): nuclear envelope forms, cytoplasm divides
• Chiasma: point at which two homologous, non- sister chromatids exchange genetic information (recombine
• Recombination occurs at prophase 1