Cell cycle

• What is the cell cycle 


  the cell cycle describes the events that take place as one parent cell divides to produce two daughter cells which then grow to full size
• What are the phases of the cell cycle called?

  G1 phase, S phase, G2 phase (interphase), M phase (miotic)
• What happens in the G1 phase?


  Cells grow, transcription occurs makes mRNA, organelles duplicate, biosynthesis, P53 gene helps control this phase
• What happens in the G0 phase?


  It is enough shoot of the G1 phase, undergo apoptosis, differentiation, senescence, some cells stay in this stage for a long time
• What is apoptosis?


  Programmed cell death
• What happens in the S phase?


  Once entered this stage, it is committed to completing the cell cycle, DNA replicates, chromosomes replicated where each one consists of a pair of identical sister chromatids, phase is rapid due to mutagenic agents so avoids mutations happening
• What happens in the G2 phase?


  Growth, replication of organelles
• What happens in the M phase?

  Also known as the miotic phase, cell growth stops, mitosis occurs (PMAT), cytokinesis occurs
• What happens at the G1 checkpoint?


  Ensures, the cell is ready to enter the S phase, DNA synthesis begins, make sure the cell is large enough and has enough proteins and organelles
• What happens in G0 checkpoint?


  Resting phase triggered by G1, some cells do not have this stage
• What happens in the S checkpoint?


  Chromosomes unwound and DNA diffuse and replicate, housekeeping genes - replicate active before inactive
• What happens in the G2 checkpoint?


  Ensure DNA has been replicated without damage and if damaged so fixes it or apoptosis occur, special ensure cell is ready for mitosis
• What happens at the M checkpoint?


  Checkpoint chemical triggers condensation of chromatin, halfway through the cycle the metaphase checkpoint ensures the cell is ready to complete mitosis
• Why are checkpoints important?

  To prevent uncontrolled division, repair DNA damage, prevent the cell cycle going backwards, make sure DNA is only duplicated once