Cell cyle

• Cell cycle

  Series of events occur in a sexually reproducing organism leading to its division and duplication. It is generated by a complex network of molecular events such as checkpoint control, cyclins and cyclin b kinases
• G1 phase


  Where the cell grows and prepares for cell division in the S phase
• Restriction point


  This ensures that the cell has enough nutrient availability and growth signals before proceeding to S phase
• S phase


  This is where Dna replication and synthesis of histones occur
• Histones


  A proteins that packaged dna into the chromosomes
• Dna damage checkpoint


  This phase ensures that the dna is intact and can replicate without error. If dna damage is detected a proteins such a p53 can halter the cell cycle and initate dna repair mechanism
• G2 Phase


  A phase where the cell completed all the necessary preparation for cell division, as well as the synthesis of microtubules and other components of the mitotic spindle
• G2/M checkpoint


  It ensure that the cell completed all the necessary preparation for mitosis before proceeding to cell division. It is regulated by a protein such as cyclin b and cdk1 complex which activate signalling pathway that initiate mitosis
• M phase


  also called mitotic phase The final phase of the cell cycle.
• Mitosis


  a process by which the nucleus divide in order to form two daughter nuclei
• Cytokinesis

  It is the physical separation of the two daughter nuclei
• Prophase


  Chromosome condense and become visible. The nuclear envelope breakdown and the mitotic spindle forms with microtubules extending from the centromere to the chromosome
• Metaphase


  The chromosome lined up at the equator of the cell and the centromere aligned at the metaphase plate.
• Anaphase


  The spindle fibers pull the sister chromatid apart. The chromosome moves toward the opposite poles
• Telophase


  The chromosomes reach the opposite pole and begins to decondense. Nuclear envelope reform and spindle fiber breaks down
• Meiosis


  a process where a sexually reproducing organism reduce its number of chromosome into gametes. It involved two rounds of cell division.
• Prophase 1

  Synapsis, crossing over and formation of tetrad
• leptene


  Prophase begins and chromosome condensation begins
• Zygotene

  Synapsis occurs and synaptonemal condensation begins
• Pachytene


  Crossing over and exchange of dna happens with non sister chromatids
• Diplotene

  Synapsis ends and chiasma is visible within bivalent
• Diakinesis

  Prophase 1 ends and nuclear envelope disintegrates
• Metaphase 1


  alignment of tetrads at the metaphase plate
• Anaphase 1


  Separation of homologous chromosome
• Telophase 1

  Formation of two daughter cells
• anaphase 2


  Mitotic soindle froms and attach to the chromosome
• Metaphase 2


  Chromosome aligned at the metaphase plate
• Anaphase 2


  Separation of sister chromatids
• Telophase 2


  Formation of four daughter cells