INTERPHASE
Many events need to occur in interphase to prepare the cell for successful division . These key processes follow the mnemonic DOCTOR and include :
● DNA replication – DNA is copied during the S phase of interphase .
● Organelle duplication – organelles are duplicated .
● Cell growth – cytoplasmic volume increases .
● Transcription / Translation – key proteins and enzymes are synthesized .
● Obtain nutrients – vital cellular materials are obtained .
● Respiration ( cellular ) – ATP production increases to drive the division process .
● DNA is present as uncondensed chromatin ( not visible under a microscope ).
● DNA is contained within the nucleus .
● “ DOCTOR ”
M PHASE
MITOSIS is divided into four distinct stages : prophase , metaphase , anaphase , telophase .
PROPHASE
● DNA supercoils and chromosomes condense ( becoming visible under a microscope ).
● The chromosomes are comprised of genetically identical sister chromatids joined by a centromere .
● A pair of specialized structures called centrosomes move to opposite poles of the cell forming microtubule spindle fibers in between them .
● The nucleus dissolves .
METAPHASE
● The microtubule spindle fibers from both centrosomes connect to the centromere of each chromosome .
● The spindle fibers contract and shorten in length causing the chromosomes to align along the center of the cell .