mitosis

• what is the importance of mitosis?

  has one round of cell division

  2 genetically identical daughter cells made

  diploid cells are made

  growth, repair, reproduction
• what happens during interphase?

  cell growth

  DNA replicates

  synthesises proteins

  prepares for mitosis
• Define PMAT?

  Prophase

  metaphase

  anaphase

  telophase
• what happens during prophase?

  nuclear membrane breaks down

  nucleolus disappears

  chromosomes condense and become visible

  centrioles divide and move to opposite poles of the cell

  DNA is free in the cytoplasm

  A) prophase

  B) metaphase

  
• what happens during metaphase?

  chromosomes move to the equator of the cell

  chromosomes attach to the spindle at their centromere

  
• what happens during anaphase?

  spindle fibres contract

  the centromere holding a pair of chromatids together divide

  sister chromatids are pulled apart to the opposite poles of the cell

  • energy for this is provided in the mitochondria = ATP= Aerobic respiration
• what happens during telophase?

  chromosomes are now at each pole of the cell

  chromosomes become longer and thinner

  spindle fibres disintegrate and nucleus reforms

  nuclear membrane forms around each group of chromosomes

  chromosomes unwind and decondense, no longer visible

  
• what happens during cytokinesis?

  cytoplasm divides into two daughter cells.
• what are the stages in the cell cycle?

  G1, S, G2
• why are their check points during the cell cycle?

  cell checks for damage during DNA replication and attempts to correct them.
• formula for mitotic index?

  number of cells observed/total number of cells undergoing mitosis x 100
• Explain how you use an eyepiece graticule and stage micrometer?

  measure the size of the object using an eyepiece graticule (has a scale etched on it)

  calibrate the eyepiece graticule using a stage micrometer
• using a stage micrometer how would you calibrate the size of the object?

  line up stage micrometer + eyepiece graticule whilst looking through the eyepiece

  count how many divisions on the eyepiece graticule fits into one division on the stage micrometer.

  
• how do prokaryotes replicate?

  binary fission
• what are the steps for binary fission?

  step 1: circular DNA replicates once + plasmids replicate many times

  step 2: cell grows and DNA loops move to opposite poles of the cell

  step 3: cytoplasm begins to divide (new cell wall starts to form)

  step 4: cytoplasm divides into two daughter cells. (each daughter cell has one loop of DNA and many plasmids)