INTERPHASE
• Most of the cell cycle (about 90%)
• Cell metabolizes and performs its function inside the organism
• Cell doubles everything in its cytoplasm– Increases the amount of
protein inside the cell– increases the number of
organelles– grows in size
• Chromosomes in the form of chromatin
Steps in Interphase
• G1– G = gap– Organelles double, cells grow in size…
• S– S = synthesis
• (DNA synthesis)
– Most important event is chromosome replication (occurs in nucleus)
• G2– Final preparation before division
PROPHASE• Early Prophase
– Chromosomes coil and condense to become visible
– Nucleoli disappears– Sister chromatids present
and held together by the centromere
– Spindle begins to form
• Late Prophase– Nuclear envelope breaks
down– Spindle attaches to the
centromeres and moves the chromosomes toward the center of the cell
METAPHASE
• Spindle is completely formed
• The centromeres on the chromosomes are lined up on an imaginary equator between the poles
• The spindle is attached to each sister chromatid and this helps to keep the chromosomes in the center of the cell
ANAPHASE• The sister chromatids are
separated and now each is considered a daughter chromosome
• Motor proteins found on the centromeres move the chromosomes toward the opposite poles of the cell
• Spindle microtubules attached to chromosomes shorten
• Spindle microtubules that are not attached to chromosomes lengthen to elongate the cell and force the poles further apart in preparation for daughter cells