Biology – Key Concepts
Cell Cycle – The life of a cell (thug lyfe). This includes growth, DNA replication, prep for mitosis and mitosis.
Interphase; first growth phase: the cell produces new proteins and organelles. Synthesis phase: the dna is replicated in preporation for mitosis. Second growth phase: the cell produces the organelles and structures needed for cell division.
Prophase; Chromatic condense into chromosomes, which are sister chromatids at this point. The mitotic spindles form. In animal cells, centrioles will move to opposite ends of the cell. The nuclear structures and membranse break apart.
Metaphase; Chromatids line up at the cell’s equator and the mitotic spindle fibres attach to the chromatids. The fibres link each sister chromatid to opposite poles. Anaphase; The sister chromatids are pulled apart by the spindle fibres. The seperated chromosomes move to opposite ends of the cell.
Telophase; cytokineses occurs. In animal cells, a cleavage furrow forms. In plant cells, a new cell wall is formed between the two new cells. Telophase finishes with the formation of two new nuclei, and the disaperance of the mitotic spindle. Cell Death/Cancer
Cells usually die because they sustain injury (rap feuds), or are no longer needed. Cell necrosis is when the cell dies because of external forces, ex: infection, toxins, etc. Apoptosis is cell suicide, which happens when a cell is no longer needed (“nobody loves me”). Example, the body gets an infection, so army cells go off to fight the infection. When the infection is over, these army cells have nothing to do with themselves so they die.
Some cells are such badass motherfuckers that they can avoid apoptosis at the right time and start multiplying like rabbits. These cells are called Cancer! Unlike normal cells, which live for about 50-60 divisions, these cancer cells can live forever! (do not stop dividing). Cancer occurs when DNA...