Cell cycle extra cards

• Describe the events in prophase

  • Chromosomes condense and become visible
  • Spindle fibres emerge from the centrosomes
  • Nuclear envelope breaks down
  • Centrosomes move toward opposite poles
• Describe the events in prometaphase

  • Kinetochores appear at the centromeres
  • Mitotic spindle microtubules attach to kinetochores
• Describe the events in metaphase

  • Chromosomes line up at the metaphase plate
  • Each sister chromatid is attached to a spindle fibre originating from opposite poles
• Describe the events in anaphase

  • Centromeres split in two
  • Sister chromatids (now called chromosomes) are pulled towards the opposite poles
  • Certain spindle fibres begin to elongate the cell
• Describe the events in telophase

  • Chromosomes arrive at opposite poles and begin to decondense
  • Nuclear envelope material surrounds each set of chromosomes
  • The mitotic spindle breaks down
  • Spindle fibres continue to push poles apart
• What is spectral karyotyping?


  This is when different segments of the chromosomes are differentially coloured, showing additional copies and deletions.
• What is translocation?


  Translocation is the process by which a segment of DNA is moved from one chromosome to another during chromosomal segregation. This can result in a loss of heterozygosity, which can result in genetic disorders or be a natural mechanism for gene regulation.
• What is S-phase generated translocation?

  1. DNA polymerase begins replication on template strand on one chromosome.
  2. DNA polymerase jumps to template strand of homologous chromosome
  3. After copying segment of homologous template strand, DNA polymerase jumps back to template strand of the original chromosome and continues copying
  4. This can result in a mismatch or mutation
• Describe how senescence can be detected

  Ki67 can be used to mark actively proliferating cells, whilst p16 is a cell cycle inhibitor that inhibits the R point and therefore stains senescent cells. These cells can also be visualised by flat enlarged nuclei and loss of structures.